1984 FJ1100. Present mileage is 36,636 miles
Original issues:
Bike ran good above ¼ throttle, but poorly at or below. Running rich, burbling, hesitating, backfires at times. Once you're are on the needles, it runs good.
Did a 10 miles test ride with mostly low speed riding (85% slow riding on neighborhood streets.)
Pulled the plugs (which are new): (See photo 1 & Carb test 2A photo)
#3 is very sooted – cylinder is running rich
#1 is slightly sooted
#2 & #4 look good – clean with tan colored insulator
Pulled the carbs:
Remove the #3 carb choke plunger and checked both it and the bore. Both look good. Blew air through the fuel and air passages for the choke circuit. All seem good. Removed and looked closely at the idle mixture jet. It seems OK.
Removed the float bowls, rested the carbs on a 60°-70° angle and checked all the float levels. I had set these a while back when I replaced all the float needles. I read on the FJ Owners forum that lower fuel levels is better for these carbs, so I set the floats a few mm high.
This time I used a digital caliper and set them as close to 22.3 as I could. (Final on all 4 is now 22.7mm measured on both sides of the floats. I confirmed these settings with a metric steel ruler. It shows 23mm – all floats, both sides
I then secured the carbs in a vice with them level in both directions and checked fuel levels.
All fuel levels are way off:
Carb 1 = 18mm below the carb body flange
Carb 2 = 20mm below the carb body flange
Carb 3 = 18mm below the carb body flange
Carb 4 = even with the carb body flange
I again removed the float bowls and re-checked the float levels. They are all at 22.7mm.
I again re-checked the fuel levels. Same results as before. I don't know how to solve this issue.
Just to see what would happen, I re-installed the carbs and synced them with a Motion Pro carb sync stick tool. Went for a 9 mile test ride:
Very poor low speed performance. Hesitating, skipping, etc.
Above ¼ throttle performance started off OK, but got poor also – with what felt like bad surging. I pulled the spark plugs once again and found all but #1 carbon fouled badly. It is now obviously running very rich on cylinders #2, #3 & #4.
To review:
I have all new float needles; all new carb O-rings, I had checked all 4 floats in a bowl of gasoline earlier when I replace the float needles. They all float and all are consistent with each other.
All float levels are now set at 22.7mm – well within Yamaha specs. It is obvious that lowering the float level caused the running rich problem to get worse. I will go back and set the floats at the high end of the spec range, but this won't solve carb #3 as it ran rich before even with a high float level.
What are your pilot screws set at and are they clean? I set my floats 22mm+, never checked the fuel level. When I set my pilots I used the thumbnail method. Screw them in so you can get a thumb-nail to catch then back them out till it lets go. This assures your starting point is consistent across all four. I know mine wouldn't run/start for shit until I fully charged the battery.. Is it all stock? Pipes, airbox, jets etc.. Also are you measuring the floats from the proper spot, from where the gasket sits to the lower round portion of the float? Just throwing some ideas at ya...
Isnt lean or rich adjusted with the mixture screw? I would be looking at the O rings in the mixture screws and making sure the washer was not crooked or something to where the O ring could leak and cause problems.
Sounds to me like your pilot jets are plugged or their circuits are plugged.
If there's any doubt maybe a complete tear-down rebuild is in order. There's a great go-by in the files section. Nothing as aggravating as having to pull the carbs on and off chasing them fckn gremlins.. :diablo: Been there, done that :empathy2:
1) What coils/spark plug boots are on your bike ? (At least the boots do not appear to be the correct Yamaha boots by looking at the plugs)
2) The carbs are not level on the bike when mounted to the engine, so you cannot use that as a reference.
3) I am not sure about the 60-70*, even though it says that in the GYSM. But if you look at the photo the carb is at 90*.
4) Have you confirmed you have the proper 2.3mm needle seats in all four carbs?
5) Have you synced the carbs with a proper sync tool?
6) When you removed the needles seats how were the carb bores where the o-rings seal (good or pitted)
7) Have you checked the pilot jets for the same ainxw in all four carbs?
8 ) What is the current jetting; Main, needle, pilot & air bleed?
Those are a few starting points.
BTW, I am not sure where you read the float level should be higher, we set all of our builds at 22mm. It does not matter if they are for a FJ or race car.
Randy - RPM
Quote from: racerrad8 on June 30, 2016, 11:45:50 PM
1) What coils/spark plug boots are on your bike ? (At least the boots do not appear to be the correct Yamaha boots by looking at the plugs)
2) The carbs are not level on the bike when mounted to the engine, so you cannot use that as a reference.
3) I am not sure about the 60-70*, even though it says that in the GYSM. But if you look at the photo the carb is at 90*.
4) Have you confirmed you have the proper 2.3mm needle seats in all four carbs?
5) Have you synced the carbs with a proper sync tool?
6) When you removed the needles seats how were the carb bores where the o-rings seal (good or pitted)
7) Have you checked the pilot jets for the same ainxw in all four carbs?
8 ) What is the current jetting; Main, needle, pilot & air bleed?
Those are a few starting points.
BTW, I am not sure where you read the float level should be higher, we set all of our builds at 22mm. It does not matter if they are for a FJ or race car.
Randy - RPM
Randy,
isn't it 2.3 mm needle seat for 1984?
Ivan
Quote from: balky1 on July 01, 2016, 03:08:55 AM
Randy,
isn't it 2.3 mm needle seat for 1984?
Ivan
Yes, 2.3mm for the non fuel pump bikes.
Thanks for catching my error. I corrected it in the original post.
Randy -
RPM (http://www.rpmracingca/)
To Randy's questions:
It has Accel coils & wires and it ran with them for many years with no problems
I am pretty sure that I'm the only one who has ever been in the carbs and they are OEM. This was before the fuel pump models came out.
I will check with the previous owner about the needle seat size, but the bike did however, run great for many years on these carbs.
I rebuilt them several months ago, but I don't remember any pitting or anything else unusual in the seats. I will verify needle seat size and condition this weekend.
I installed all new O-rings then along with the new float needles
All pilot jets are new
Carb jetting is:
mains - 122.5
pilots - 40
air pilots - 160
needle clips - 2nd groove down from the top
idle mixture jets 2-3/4 turns out
Carbs sync with a Motion Pro carb stick tool
If I understand correctly, a higher float level would equal a lower fuel level would it not? The needle would seat sooner
Not sure what ainxw is in question #7. Is that a typo?
Jetting looks fine (to me) although #40 pilots with 160 airs are equivalent to 37.5 and 155's which is the stock USA jetting.
I like larger pilots, they don't clog as easy. Your #40 pilots will work better with smaller 155 air bleeds.
You are Correct, the larger the measurement number, the lower the floats and fuel level.
Are you measuring from the correct point? http://www.fjowners.com/index.php?topic=9560.0 (http://www.fjowners.com/index.php?topic=9560.0)
Cylinders #1,2 and 4 will be dialed in with your carbs, I'm worried about #3
How long since your last valve adjustment? Any tight valves found on #3?
How are your hot compression numbers?
Have you had the needle jets (emulsion tubes) out? Perhaps the main air bleed is clogged? What brand of air filter are you running?
Not enough mileage for the needle jets to be elongated and at 1/4 throttle it sounds like an idle circuit problem. The PO made the common mistake thinking a larger number means a richer jet. The 160 air pilot jet basically negated the 40 idle fuel jet. 122 mains seems big to me but that's not your current problem.
When you try to measure the fuel level, you need to let a bit of fuel run out of the float bowl before making the measurement. I lower the clear tube to let it overfill then raise it back up so fuel needs to run back into the bowl then make the measurement. Sometimes I even blow fuel back into the bowl and let it refill.
Randy,
Not picking on you, but if the fuel level is measured at the center of the float bowl then it doesn't matter what angle the carbs are sitting at. The level pivots at the center of the bowl and is the same at all angles.
Some history on the bike.
P.O. had the engine reworked at 18,000 miles- Bored to 1,188cc with 10.25:1 ratio Wiseco Pistons, Ported heads and oversize stainless steel valves. Cam sprockets were slotted for precise cam timing. He installed an oversize oil cooler at the time of the engine re-work. It has Accel Super Coils, and a 4 into 1 Supertrapp exhaust with K&N pod air filters.
The bike sat up in a garage, partially disassembled for 8 years. Some gas was inadvertently left in the removed carbs, but the gas tank was drained dry. I thoroughly cleaned the carbs and installed all new O-rings and float needles a few months ago when I bought it. It has had this low speed running issue since I got the bike running. It also was very cold natured, so I went back and installed #40 pilots which helped the cold starting issue.
I have removed and closely examined the emulsion tubes. All 4 look good. I actually removed and re-checked #3 again last weekend.
You are correct that the main jets are too large still. I had to start somewhere, so I went down one size. Even so, it still runs damn good at high throttle openings, but the exhaust is still black.
My current problems are before the needles even start to affect things in any significant way.
I am checking the floats from position "B" if you look at Randy's post about setting float levels.
Recent compression test results are: #1 = 120 PSI, #2 = 120 PSI, #3 = 110 PSI, #4= 110 PSI (Repeated 4 times on a warm engine with the throttle wide open)
Recent valve adjustment done – all are in spec and at the loose end of the range
This bike was running great when the P.O. stored it. He had gotten a newer bike and had just quit riding this one. His goal was to do some restoring on it, but he lost interest.
Took the carbs back off today. Removed all needle & seats. All look fine. They are 2.3mm, but this is the correct size for my gravity fed bike.
Put all 4 floats in a bucket of gasoline again. All are floating and all are consistent with each other. Removed and checked all 4 pilot jets.
All are clear and all have the same #40 on them. (Of course if they were plugged, it would run lean or not at all once the choke was closed)
Does the choke linkage articulate correctly? #3 choke hanging open, even a little?
I wonder if you have a leak in the choke circuit causing the extra fuel?
The choke circuit and linkage system is the 1st thing I checked. Everything is working correctly. The choke plunger for #3 looks fine.
I'm still thinking it's something in the float system because when I had the float levels set high, only #3 was running badly rich.
#1 was just a little rich. #2 & #4 looked great (refer back to the 1st plug photo) I feel sure that if I set the float levels high again,
it would do fine on 2 & 4 and just a little rich on #1. Setting them too high doesn't solve the problem, only masks it.
This is so frustrating to me. I don't want to toot my own horn, but I am an ASE Master Certified Auto technician from way back when
all cars had carbs. I have rebuild 100s of them! I have been a motorcyclist for over 40 years and have always done my own work.
To have these simple carbs kick my ass is very humbling. I have taken these things off this bike about 7 or 8 times now.
OK, I'm done pissing & moaning now. I really need a solution.
Yes, I can tell by your correct terminology and diagnostic steps you know your stuff.
I had a problem with the oil rings on the 82mm Wiseco pistons on my bike. Under high vacuum, (closed throttle high rpm) the oil rings would not seal. Vacuum would pull the oil up past the rings. The plugs would foul, and for some reason especially #3.
The carbon buildup was excessive.
Only since I switched to the 83mm Ross pistons, did the problem go away.
The fouling is clearly rich fuel mixture. It is very black and fluffy.
There is no hint of any oil at all. Also, on the 2nd test, #1,2 & 3
completely carbon fouled after only 9 miles of riding.
I wasn't sure I would make it home.
These engine mods were made at 18,000 miles and it has run great
for 18,000+ more. There is no blue smoke from the exhaust that I can see.
I'm surprised you can run with your choke off at 10 miles. My 86 needs at least that before it runs 100% right. Without choke and cold it will run like arse at 1/4 or less.
I'm in South Carolina, so even when it's cold, it's not really cold. You're in Maine. Isn't that about 20 miles from the artic circle?
Were freezing our butts off when it gets down to 30. I spend some time in Maine one summer and nearly froze to death at night.
With the #40 pilots, this bike will crank right up. It pops, spits, farts and backfires for 3 or 4 minutes then it will idle on the 2nd
step of the choke. 3 or 4 more minutes and it will pull away OK But, it still runs poorly below 1/4 throttle.
I know you're running rich, but that "pops, spits, farts and backfires" description is a classic indication of clogged idle circuit(s).
I've got a DJ carb kit with 40 idle jets and 140 (may be 144, I forget) air pilots. It cranks right up and I can turn the choke off at about 1 minute and drive away.
In the winter, I drive away with 1/2 choke for about a mile then it's off.
Take a look at the discussion by Factory Pro on worn needle jet orifices.
They say, "if lowering your fuel level 1mm does not fix your rich condition, check your needle jets for wear. It's not that uncommon..."
Scroll down: http://www.factorypro.com/jets,needles,emulsion_tubes,pilot_jets.htm (http://www.factorypro.com/jets,needles,emulsion_tubes,pilot_jets.htm)
Hey, while reading these few last posts, your probs reminded me of mine from last year. I had a great running bike also which leaked fuel in the crankcase. To shorten the story, I removed the carbs to change seats and needles and after that it never ran good with sputtering, backfires etc. I tried tons of things I've read here on the forum, nothing helped. It also had the lover RPM range problem. So I even changed the pilots with new ones since one of mine was stripped so I thought that could be it, but didn't help. I got to a point where I drove the bike to a more experienced mechanic who, of course, found the prob immediately.
One of the rubber manifolds was hard and didn't seal well anymore after I initially removed the carbs. I even did the start spray test which showed me no evidence of non-sealing manifolds, but the guy knew it was it, changed it and I was good to go.
My point is, even if the manifolds look good to you without cracks, they could still be the thing to blame.
Ivan
Quote from: a.graham52 on July 02, 2016, 06:31:48 PM
I'm surprised you can run with your choke off at 10 miles. My 86 needs at least that before it runs 100% right. Without choke and cold it will run like arse at 1/4 or less.
Usually choke to start up when cold....10-15 seconds choke off...and runs fine. That being said I never push it hard or go past 3500 RPM for the first 5 minutes or so anyway.
Jeff
I don't feel that my choke issues have anything to do with this running rich problem. I don't ride the bike in 90 degree summer with the choke on. It can't be a plugged jet, that would cause a lean running problem (unless it was an air pilot jet) However, all jets, passages, etc. are clear. There is no pitting in the bore for the needle seats. I have removed the emulsion tubes again and re-checked. (see tube pics) I can't see any oval shaped wear, or any other wear at all but I am old & don't see as well anymore. I didn't get very good straight in photos, so some look oval shaped due to the angle of the camera. They all look consistent with each other. These tubes do make the most sense as a cause of the problem. I would just replace them all, but at $30 each, I need to be sure. I don't mind spending the money if I could have a high degree of confidence that it would solve the problem. Randy, could I send these tubes to you for an opinion?
Quote from: ergojack on July 04, 2016, 04:40:50 PM
Randy, could I send these tubes to you for an opinion?
Yes, but make sure they are attached to the carbs.
The reason I say that is, it looks like them are probably the wrong emulsion tubes. It is hard to tell from the photos but the tubes appear to be the shrouded version. If those are installed into the flat bottom slide carbs it will never run right. Then if someone put the wrong needle that is a problem as well.
Quote from: ergojack on July 02, 2016, 10:31:54 AM
The bike sat up in a garage, partially disassembled for 8 years. Some gas was inadvertently left in the removed carbs, but the gas tank was drained dry. I thoroughly cleaned the carbs and installed all new O-rings and float needles a few months ago when I bought it. It has had this low speed running issue since I got the bike running.
This bike was running great when the P.O. stored it.
I think it is time for a set of skilled eyes to go through them and see what is going on.
Randy - RPM
Randy,
Please put the ship to address in here and I will re-assemble and send the carbs to you.
Should I leave them ganged, or separate them?
RPM
410 South 5th Av
Oakdale, Ca 95361
Leave the all together please.
Randy - RPM (http://www.rpmracingca/)
I hate to say it but I have seen times when people have been lees than accurate in their description when selling something. Heck the P/O could have been fighting the same demons due to wrong parts installed and just didnt say anything thinking you'd stumble right onto the problem and fix it. My carbs where Frankensteined when i got my bike, I had to get several things to complete these carbs back to stock.
The problem is *nobody* knows about the difference between the needle jets (aka emulsion tubes, jet nozzles, etc) for the early FJ flat bottom slide CV36 Mikuni's and the later curved bottom slide Mikuni's.
Nobody but Randy at RPM that is...... :good:
Order a set of new emulsion tubes from the experts at Factory Pro or from you local Yamaha dealer, you will get the shrouded version. Then you will wonder why your flat bottom carbs run like shit.
Randy,
I'll get these back together and headed your way. It might be the weekend before I get them boxed up.
I do have a long history with the P.O. of about 20 years. I had actually ridden this bike many times prior
to its being stored. Since it has been sitting up for so long, he doesn't remember much. It may have had
some issues that he just doesn't recall. The P.O. didn't even have the bike up for sell. I offered to buy it.
I just hated to see a classic old bike sitting in a garage unused. What's the old saying about no good deed
goes unpunished...
You knew the previous owner of this bike for 20 years and you've ridden it many times before it went into storage? Then you come along and purchase it. That alone should tell you that the parts in the carbs had functioned properly so it should be safe to say the parts are correct for the model. Looking back through your posts you never once mentioned soaking the carb bodys in carb cleaner which is standard, you didn't mention running them through a sonic bath which is what all the pro carb guys do without fail. You only said you blew air through the ports. That bike had 8 years in storage to harden shellack into those ports. Your symptoms are that of dirty pilot circuits as mentioned by previous posts. As stupid as this may seem given what you've been through, it sounds like your carbs are simply still dirty. Just my deduction from the given information.
I didn't mention soaking in carb cleaner, because as a long time mechanic, it is understood that soaking is part of a carb rebuild. I disassembled all 4 carbs and soaked them individually for 24+ hours each in carb cleaner. The carbs sat up for 8 years, but they only had a little gas in the float bowls. They were removed from the engine; flipped upside down and shaken to drain then, but the PO didn't remove the float bowls or loosed the bowl drain screws so a small amount of fuel remained in the bowls. He then stored them in a box.
Once again though, a plugged pilot circuit would cause a lean running condition - not a rich condition. Go back and look closely at the spark plug photos - black fluffy carbon after 8 or 9 miles of riding is symptom of a rich running condition.
Even though I was incorrect about the pilot/lean issue, my point still stands, the parts in those carbs worked before and you yourself rode the bike with those parts so they have to be correct. Thus the issue still remains but I seriously doubt it has anything to do with improper emulsion tubes unless the P/O switched those carbs out while in its storage days? So what would cause a carb to draw more fuel through the pilot circuit? Is the pilot screw the only variable that can alter the amount of fuel being pulled to change rich /lean conditions or do air jets play into that as well?
Here's my feel... unless you rode the bike with 1/4 throttle or less 90% of the time, then your plugs are not a good indication of pilot circuit. What u discribe one "paper" is a plugged pilot circuit. If any of the four circuits is plugged, then no where near enough fuel will get through and a massive amount of power in that range will be lost. You will get popping, you will get stumbles. Just Crack that choke open in small increments while riding. This will make up for a lack of fuel if there is one and it will run smooth in that area. However with the choke on you may run worse in other areas and is normal for what your doing. Just a little choke at a time until you notice a different for better or worse.
The question remains: If you have flat bottom slides (typical on early FJ's) and you have the shrouded type emulsion tubes, you will have rich running problems.
The shrouded tubes look like this:
(http://rpmracingca.com/prodimages/large/Carb%2050H-14941-92-00-1.jpg)
These above emulsion tubes should be only used with the curved bottom slides.
Using these shrouded emulsion tubes on flat bottom slides, the shroud sticks up and holds the slide up (and thus the needle).
The shrouded tubes are designed for curved bottom slides.
Check this out and let us know.
Quote from: Pat Conlon on July 07, 2016, 10:13:04 PM
The question remains: If you have flat bottom slides (typical on early FJ's) and you have the shrouded type emulsion tubes, you will have rich running problems.
The shrouded tubes look like this:
(http://rpmracingca.com/prodimages/large/Carb%2050H-14941-92-00-1.jpg)
These above emulsion tubes should be only used with the curved bottom slides.
Using these shrouded emulsion tubes on flat bottom slides, the shroud sticks up and holds the slide up (and thus the needle).
The shrouded tubes are designed for curved bottom slides.
Check this out and let us know.
I will apologise in advance for hijacking this thread but my question relates to the above information. The '85 FJ I'm currently working on, has choke issues.
It starts on the choke but after about 20-30 seconds running on it, stalls, it will re-start with a little throttle, choke off but will not idle until fully warmed. Any further use of the choke just stalls it. The carbs are the early model flat bottom slide version but have been fitted with new cut away slides. Who ever did the rebuild left the original flat top emulsion tubes in it. What effect, if any, would this have on tuning the carbs, especially the choke function? I suspect it won't be effecting it but am open to views from others with more experience than me.
Regards, Pete.
Let me ask you this, when you apply the choke does the bike raise in RPMS relative to the choke position? Full choke for me is about 3K RPM or so, but sometimes it stumbles on that much fuel when cold and needs a blip of throttle to kick it up to high idle. Further more my bike dont really like much more than about 20 or 30 seconds of full choke, I have to reduce it down to about 1/8 to let it warm up. I actually prefer to shut the choke off and just hold the throttle at 2 or 3 K rpm until it warms, I can tell when its ready as it will sit at idle and purr like a kitten. Mine is cold hearted for sure.
After reading Pats post I'm starting to raise eyebrows about my own carbs and rebuild. My bike was completely raped of parts as it was in fact purchased as a parts bike to serve two other FJ's. I know one of those bikes was an older red and white model and I think the original carbs from my 90 went onto that bike. Heck I might need to tear my carbs back down and have a closer look. Shoot depending on the cost I might send them to Randy as well, pretty confusing to say the least when looking at those emulsion tubes, I don't have a clue what you guys are talking about when you say curves and shrouds and so on. But that's why I'm here, to learn how to use a 30 year old bike and be able to have it get me back home.
Only the very early FJ1100's had the flat bottom slides. I recall Randy mentioning that about 1/2 the way thru the 1985 production run, Yamaha went over to the curved bottom Mikuni's.....so for most folks, this is not an issue, just us early FJ owners.
You can see without removing the carbs. Pull the air filter off....see the slides? The bottoms will be curved, or flat. lf they are curved, you're fine.
If you lift the slides you will see the tip of the shroud poking thru into the throat of the carb, that's why the slides should be curved.
The tip of the shroud of the emulsion tube will hold up the flat bottom slides.
Quote from: oldktmdude on July 08, 2016, 06:30:30 AM
The carbs are the early model flat bottom slide version but have been fitted with new cut away slides. ....
Hey Pete, Are you *absolutely sure* you have the flat bottom carbs with curved bottom slides?
I understand that is a no-no. Putting different slides into the bore of a carb. The slides are closely mated to the bore. That's why when rebuilding you need to track which slides come out of which carb, just so you are sure not to mix them up and put different slides into different carbs...
....let alone putting completely differently designed slides (curved bottom) into a set of carbs that were designed for flat bottom slides.
Quote from: oldktmdude on July 08, 2016, 06:30:30 AM
Who ever did the rebuild left the original flat top emulsion tubes in it.
Well, you could try using the proper shrouded emulsion tubes with your curved bottom slides....see if that helps.
Quote from: oldktmdude on July 08, 2016, 06:30:30 AM
What effect, if any, would this have on tuning the carbs, especially the choke function? I suspect it won't be effecting it but am open to views from others with more experience than me.
If this is the case, you are in uncharted waters. Along with the difference in the design of the slides (curved vs. flat) and the issue of slide vs carb bore mating, how about, what's different internally (in the body of the carbs) between the flat bottom carbs and the curved bottom carbs?
I don't know the answer to that question.
My bike has flat bottom slides and un-shrouded emulsion tubes (See attached pic).
I'm just not sure if I have some wear in the tubes that I can't see.
I thought the flat-bottom slides used a really think jet needle?
Are your needles adjustable? If so then they may not be correct (aftermarket?).
Also, if they are too small, it will run really rich.
Quote from: Pat Conlon on July 08, 2016, 12:06:29 PM
Quote from: oldktmdude on July 08, 2016, 06:30:30 AM
Hey Pete, Are you *absolutely sure* you have the flat bottom carbs with curved bottom slides?
If this is the case, you are in uncharted waters. Along with the difference in the design of the slides (curved vs. flat) and the issue of slide vs carb bore mating, how about, what's different internally (in the body of the carbs) between the flat bottom carbs and the curved bottom carbs?
I don't know the answer to that question.
Pat, I don't know the history of the bike, my conclusion was drawn from the fact that the carb bodies look to be 30+ years old, emulsion tubes are also old looking but the slides and diaphragms look fairly new, no pin holes, rubber still very soft and new looking and the slides are still very shiny. The bike was run on a dyno 3 weeks ago and the air/fuel ratio was fairly good throughout the rev range but he advised to fit 1 size larger mains. The main issue we are having (not my bike) is the choke problem. It will not accept any choke application after the initial 20-30 seconds of full choke and will not idle until fully warmed up.
PS. Pat, please feel free to shift this discussion to a new thread if you want. I have not intended to hijack the original thread but thought the discussion of mismatched slides and emulsion tubes may be of help to others.
Regards, Pete.
P.O. put in jet kits very early on. It had run for years on the existing carb setup. The needles are adjustable - 2nd groove down from the top.
Ok, so you have the correct emulsion tubes for your slides....cross that off the list :good2:
Hooli has a sharp eye and good point (as usual)
That does not look like the stock Mikuni needle, it's too thin. I think you have a Dyno Jet needle.
Dyno jet kits are well and good but, they use a proprietary needle (thinner) with their proprietary jets.
You can't mix and match Mikuni components with Dyno jet components.
If you are using Mikuni jets (you are) you should use a thicker Mikuni (adjustable) needle.
Also, check the slide springs you have.... Chances are if you have the Dyno Jet needles, you also have the Dyno Jet springs
The Mikuni slide spring is stronger, it takes more vacuum to raise the slides, perfect for the larger Mikuni jets.
The Dyno Jet slide springs are softer, the slides pop up faster, again, it's fine with the Dyno Jet kit components but not so good with Mikuni components.
Don't mix and match Mikuni goodies with Dyno Jet goodies.
+1 on the needle. Looks like the ones on my original set up. Also check the slide spring it to would probably be also Dyno jet. I took all that out and went back to a full stock set up from RPM when I rebuilt the carbs. Well almost full stock. I ordered the adj needles from RPM. Replaced the slide springs with stock units.
Here is a pic of the spring. Stock one is on the left.
(http://fjowners.com/gallery/7/1651_18_03_14_5_26_13.jpeg)
George
Quote from: Pat Conlon on July 08, 2016, 11:11:39 AM
The tip of the shroud of the emulsion tube will hold up the flat bottom slides.
Pat - you've said that several times, but I don't think it is true. My '84 came with flat bottom slides and shrouded emulsion tubes (PO had swapped them in I guess). No mechanical interference issues and the bike actually ran well. My guess would be the shroud was added later to further increase vacuum seen by the main jet at high velocities in the carb body. This might have evolved (along with curved bottom slides) to increase main jet flow at or near WOT and improve performance after the FJ had been out for a while with the small main jets required by emissions testing... speculation I know, but I think it makes sense.
I returned my carbs to the proper unshrouded e-tubes and tuned them via the Factory Pro procedure... they work well now, but have MUCH bigger mains largely to keep from going lean at near WOT. I think the shroud would help with this (based on above conjecture) and allow smaller mains, but haven't spent enough time to prove or disprove.
Frank
I sure am learning allot about these carbs watching you guys diagnose this issue. :good2:
Having the wrong jet needles would explain why it's so rich. That needs to be addressed.
Going back to your previous comment about spitting and farting, I think you have one or more idle circuits that are not in good shape.
You could chase your tail for many months on this. Get with RPM and get a quote on what it would take to get your carbs sorted. If you enjoy riding your FJ then whatever he quotes is well worth it.
Randy and Robert are good people.
Quote from: Flynt on July 08, 2016, 08:26:58 PM
I returned my carbs to the proper unshrouded e-tubes and tuned them via the Factory Pro procedure... they work well now, but have MUCH bigger mains largely to keep from going lean at near WOT. I think the shroud would help with this (based on above conjecture) and allow smaller mains, but haven't spent enough time to prove or disprove.
Frank
I remember working on an early '85 model FJ that had the flat bottom slide. It had an early Dyno Jet kit installed. The jet needles were these HUGE blunt rods and the DJ main jet was a 180! Totally different than what my '85 had with the curved slides and shrouded emulsion tubes. My Dyno Jet kit was way different using 110 DJ mains and the 144 air pilot jet. I bumped the idle jets to #40 and the thing is absolutely perfect.
Hello Frank, my experience was different than yours.
At the 100k mile mark on my bike I felt it was time to replace my e-tubes. Unknowingly I put a set of new shrouded tubes on my flat bottom carbs and I could never get her to idle right. Idle was just ok, a bit rough, definately not as smooth as it was with the old (unshrouded) tubes.
Yes, there is interference with the shroud and the bottom of the (flat bottom) slide.
I ran my bike this way for another 35k miles until it became time for some top end engine work.
Randy noticed this condition with the shrouded e-tubes when he rebuilt my engine. He called my attention to it. He also could not get my old carbs to idle right.....and if he can't, nobody can.
I've since converted over to the later carbs and all is well.
Yes, yes, yes, Randy knows his stuff on these carbs, as many satisfied customers will testify, inc. myself.
I agree 100% with Hooligan.
You are correct that they are D.J. needles. What puzzles me is that those needles (according to receipts & records) were installed nearly 20 years ago and the bike ran
very well for all those years. I see and ride with the P.O. often, but he is a tinker who loves to mess with things. The last time I rode this bike was probability 2 or 3 years
before he stored it. He doesn't remember doing anything to it, or remember any running issues before he stored it. That being said, he is old and cursed with CRS so
there is just no telling. It is also possible that the P.O. replaced the D.J. needles with some others sometime before he stored the bike and created this slow running problem.
I think you have got it in your mind that a dirty pilot circuit can only cause a lean running issue, like if its clogged then it can only lack fuel and that can be the only outcome. I'm not a master tech mechanic but I do have a general idea of how that fuel gets pulled from that jet, its not pushed out, its not pumped out, its pulled out by way of vacuum/suction from the piston. Now, if those circuits are dirty BEFORE the air reaches the jet, would it not decrease inlet air thus pulling more fuel by default? Ever since I started reading this thread I couldn't accept that your carbs had problematic wrong parts installed, the bike ran for many years on those same parts.The only variable that ties your issue to other known issues is that those carbs sat for many years. I know you soaked them carbs for 24 hours, did you run them through an ultra sonic cleaner afterwards? My thoughts are this, you don't have those carbs clean enough yet, you only think that you do. If you ran them through the ultrasonic with vinegar/water mix, I'd suggest atleast two or three more cycles through the ultrasonic with maybe straight vinegar this time. Its been said several times in this thread by many different guys that dirt is more often than not the main culprit for your issue, you as a master tech mechanic know this as well. I can tell you this, I think you have one of them carbs cleaned properly. You're focusing on the 3 carbs running rich when you should be asking yourself, why does the one carb run perfect? After all,it has the same parts as the other three that are rich.
Quote from: Pat Conlon on July 08, 2016, 12:06:29 PM
I understand that is a no-no. Putting different slides into the bore of a carb. The slides are closely mated to the bore. That's why when rebuilding you need to track which slides come out of which carb, just so you are sure not to mix them up and put different slides into different carbs...
.....and the issue of slide vs carb bore mating
Pat, why does this matter?
Noel
Hey Noel, this is something I've been taught and the best I can figure is to prevent or reduce the rattling of the slide.
When the slides rattle, the needles also rattle causing wear on the needles and emulsion tubes.
Quote from: Pat Conlon on July 08, 2016, 11:35:43 PM
Yes, there is interference with the shroud and the bottom of the (flat bottom) slide.
OK... I'll check it when I'm in there next. I'm pretty sure mine didn't touch the slides, but whatever. The shrouds go with the curved bottom slides by design and no argument there. That's why I got rid of the shrouds. I will say that tuning the flat bottom, shroud-less carbs is a bit of a bitch, very finicky at 3/4 WOT. The curve/shroud design is an improvement in ease of use at least (for some reason)...
Frank
Yeppers Frank, I'm sure the curved bottom slides and shrouded e-tubes are a superior design.
What I'm unsure of...are there also internal differences in the carb body? Different air/fuel/choke passages?
Quote from: Tuneforkfreak on July 09, 2016, 09:25:17 AM
You're focusing on the 3 carbs running rich when you should be asking yourself, why does the one carb run perfect? After all, it has the same parts as the other three that are rich.
^^^ That is a very valid point, why indeed?
If you go back & look at the plugs, you will see that in low speed test #1 with all fuel levels set low, (floats set high) cyls. 2 & 4 were running clean, #3 was badly carbon fouled & #1 was slightly carbon fouled.
Low speed test #2 with all float levels set to 23mm (fuel levels at normal), cyls. 2,3 & 4 were badly carbon fouled and cyl. #1 was getting fouled, but not as bad as the others. There is no perfect running cylinder. I have no doubt that if I went back & set the fuel levels low again, it would run as it did in test #1. I also believe that in test 2, #1 would have fouled out also if the bike had run long enough. As it was, I barely made it back to my shop. It seems obvious to me that the problem is across all 4 carbs.
OK lets go back to some things you've said then. You replaced the float needles, you did not mention changing the seats along with the needles, so one would have to ask, did you change them as a set? I know you're gonna come back and say "every mechanic knows you change needles and seats together" but you're on a forum trying to diagnose an issue with the help of multiple people and the tiniest bit of info cannot be left to the imagination. You've said adjusting the float level has changed rich/lean conditions somewhat so lets just stick to that area for now. Do you have the needles installed on the floats correctly? If you have them backwards the retainer spring can drag on the float lever ( or at least on my 90 carbs they can). You said yourself that your eyes are not what they used to be and your issue with these carbs, at least in my mind, has to be some little over looked step giving you fits.
1) Needles and seats installed correctly
2) Floats adjusted properly
3)Pilot screw has 1) O ring , 1) washer and a spring then is set
Outside of everything being spotless clean, the proper jets installed and the slide needle being set to proper height, these are the variables within your control to get that fuel into that cylinder properly. 99.999% of the time a guy would put these together after a thorough cleaning and never look back. What did you do differently that puts you in that rare .1%?
Quote from: Flynt on July 09, 2016, 11:02:03 AM
Quote from: Pat Conlon on July 08, 2016, 11:35:43 PM
Yes, there is interference with the shroud and the bottom of the (flat bottom) slide.
OK... I'll check it when I'm in there next.
Upped my mains to 120s yesterday and checked this out. Flat bottom slide its 2mm above the top of the shrouded e-tubes... no interference, at least on my bike. This makes sense to me... there are not special needles for the early carbs, so the point where the needle mounts to the slide must be the same height relative to the e-tube for either curved or flat. Maybe Randy or Robert can check, but I bet the curved slides are the same length to the center as the flat bottom slides.
The 120s fixed my 3/4 to WOT lean condition (really mild, but bugging me more as is getting warmer). Butt dyno registered more WOT grunt as well... Happy Stormy! (now at 42.5/160 with 2.25 turns, 120 mains and needles out one notch, float level 1mm lower, and with 5 degrees ignition advance). I'll check cold start behavior today and then make sure the carbs get a decent workout, maybe out on the coast.
Frank
Ok, thanks for the follow up Frank. I thought you went back to the non shrouded tubes...So you put back in the shrouded tubes?
Your '84 flat bottom slide carbs should be exactly like my old carbs, so I wonder what Randy's concerns were?
I'll let him chime in.
Quote from: Pat Conlon on July 10, 2016, 02:38:01 PM
I thought you went back to the non shrouded tubes...So you put back in the shrouded tubes?
Yep. I was stepping the needles down also, so I put one of my old e-tubes back in to check it out. Then swapped back my non-shroud stockers.
Frank
Quote from: FJ_Hooligan on July 01, 2016, 07:09:46 PM
Randy,
Not picking on you, but if the fuel level is measured at the center of the float bowl then it doesn't matter what angle the carbs are sitting at. The level pivots at the center of the bowl and is the same at all angles.
David, I think you are referring the external measurement of the fuel level in the float bowls.
I was referring to the angle recommended by Yamaha for measuring floats levels with the bowls off and a tool.
This photo here
(http://i1215.photobucket.com/albums/cc517/racerrad8/FloatAdjust013.jpg~original) (http://s1215.photobucket.com/user/racerrad8/media/FloatAdjust013.jpg.html)
I also am not sure if the external float levels will be the same regardless of carb angle. The float pivots at the rear of the carb near the needle. Since they are towards the rear, it would seem to me if you raised the rear at the pivot that will also raise the fuel level in the bowl.
I know I have read before that some guys who have jacked up the rear of their bike have lowered there fuel level to stop the fuel from leaking out of the now completely covered choke enrichment tube. The vacuum break hole at the top of the tube is covered and it will drain the bowls down until the hole is uncovered and the vacuum breaks.
That will have to be a future test someday to see for sure.
Randy - RPM
Re: Raised rear end vs. fuel level and vacuum break...I wonder if that is why this mod makes sense
http://www.fjowners.com/index.php?topic=7056.0 (http://www.fjowners.com/index.php?topic=7056.0)
Quote from: Pat Conlon on July 12, 2016, 04:06:50 PM
Re: Raised rear end vs. fuel level and vacuum break...I wonder if that is why this mod makes sense
http://www.fjowners.com/index.php?topic=7056.0 (http://www.fjowners.com/index.php?topic=7056.0)
And that is why I stand by my statement then, as I do now about float height and ultimately carb angle.
Randy - RPM
Randy, so if the bike has the back end raised and because of this, the fuel level covers the hole in the tube, the additional (drilled) 1mm vent hole shown in the mod would help break the siphon action?
Quote from: Pat Conlon on July 12, 2016, 04:51:32 PM
Randy, so if the bike has the back end raised and because of this, the fuel level covers the hole in the tube, the additional (drilled) 1mm vent hole shown in the mod would help break the siphon action?
I believe so, but I have never personally attempted. My concern is the additional venting source to draw air from. But, it might not matter as noted in the post, but again I have never attempted.
Randy - RPM
Randy,
Sorry, I must have misinterpreted your meaning. You're correct, I was referring to the external FUEL level measurement. I totally agree with you on the FLOAT height measurement.
I've been on vacation & haven't fooled with the bike in a while.
I went to see the P.O. & he still all the OEM carb parts. I am going to put
the OEM needles in. He had some 120 mains that I'm going to install also. They may
still be a little large, but are smaller than the 122.5s I have in now. I know they don't
have anything to do with my problem, but since the carbs are off, now is the time
to change them. I just ordered some 155 air bleed jets from Randy. This engine is
bored to the 1200 specs. & 155s are what it is suppose to have. We will see how it runs
after this.
Quote from: oldktmdude on July 08, 2016, 06:30:30 AM
Quote from: Pat Conlon on July 07, 2016, 10:13:04 PM
The question remains: If you have flat bottom slides (typical on early FJ's) and you have the shrouded type emulsion tubes, you will have rich running problems.
The shrouded tubes look like this:
(http://rpmracingca.com/prodimages/large/Carb%2050H-14941-92-00-1.jpg)
These above emulsion tubes should be only used with the curved bottom slides.
Using these shrouded emulsion tubes on flat bottom slides, the shroud sticks up and holds the slide up (and thus the needle).
The shrouded tubes are designed for curved bottom slides.
Check this out and let us know.
I will apologise in advance for hijacking this thread but my question relates to the above information. The '85 FJ I'm currently working on, has choke issues.
It starts on the choke but after about 20-30 seconds running on it, stalls, it will re-start with a little throttle, choke off but will not idle until fully warmed. Any further use of the choke just stalls it. The carbs are the early model flat bottom slide version but have been fitted with new cut away slides. Who ever did the rebuild left the original flat top emulsion tubes in it. What effect, if any, would this have on tuning the carbs, especially the choke function? I suspect it won't be effecting it but am open to views from others with more experience than me.
Regards, Pete.
Hi everyone,
Just doing my carbs first time for FJ. Bike came completely Frankenstein and did not even worked. I was told carbs were re-built however when I took it apart, I noticed that all was BS. Broken float legs glued with epoxy! 0-rings under main jets! broken vacuums etc.
Right now, carbs have curved bottom slides and flat emulsion tubes which i believe they call un-shrouded. Should I change emulsion to OEM shrouded and needles as well?
My set up as of right now:
112.5 main
40 pilot
160 air
3 1/4 turn out
needle clip 3 position from the top
KN filter in the box
F1 double slip on exhaust
Any recommendation will be much appreciated.
Thank you and have a good day guys.
Quote from: MarioR on April 03, 2021, 09:45:39 AM
Quote from: oldktmdude on July 08, 2016, 06:30:30 AM
Quote from: Pat Conlon on July 07, 2016, 10:13:04 PM
The question remains: If you have flat bottom slides (typical on early FJ's) and you have the shrouded type emulsion tubes, you will have rich running problems.
The shrouded tubes look like this:
(http://rpmracingca.com/prodimages/large/Carb%2050H-14941-92-00-1.jpg)
These above emulsion tubes should be only used with the curved bottom slides.
Using these shrouded emulsion tubes on flat bottom slides, the shroud sticks up and holds the slide up (and thus the needle).
The shrouded tubes are designed for curved bottom slides.
Check this out and let us know.
I will apologise in advance for hijacking this thread but my question relates to the above information. The '85 FJ I'm currently working on, has choke issues.
It starts on the choke but after about 20-30 seconds running on it, stalls, it will re-start with a little throttle, choke off but will not idle until fully warmed. Any further use of the choke just stalls it. The carbs are the early model flat bottom slide version but have been fitted with new cut away slides. Who ever did the rebuild left the original flat top emulsion tubes in it. What effect, if any, would this have on tuning the carbs, especially the choke function? I suspect it won't be effecting it but am open to views from others with more experience than me.
Regards, Pete.
Broken float legs glued with epoxy! 0-rings under main jets! broken vacuums etc.
Right now, carbs have curved bottom slides and flat emulsion tubes which i believe they call un-shrouded. Should I change emulsion to OEM shrouded and needles as well?
My set up as of right now:
112.5 main
40 pilot
160 air
3 1/4 turn out
needle clip 3 position from the top
KN filter in the box
F1 double slip on exhaust
Any recommendation will be much appreciated.
I'd send the whole thing to RPM... replace carb bodies that are shot, get all fueling circuits working properly, then tune to their recommendation... the flat bottomed slides can be used and, at least I believe, will give you a more crisp response... I think the curved slides are smoother (boring) in roll on... :bomb: :blum1: :bomb:
Frank
Quote from: Flynt on April 03, 2021, 08:38:24 PM
Quote from: MarioR on April 03, 2021, 09:45:39 AM
Quote from: oldktmdude on July 08, 2016, 06:30:30 AM
Quote from: Pat Conlon on July 07, 2016, 10:13:04 PM
The question remains: If you have flat bottom slides (typical on early FJ's) and you have the shrouded type emulsion tubes, you will have rich running problems.
The shrouded tubes look like this:
(http://rpmracingca.com/prodimages/large/Carb%2050H-14941-92-00-1.jpg)
These above emulsion tubes should be only used with the curved bottom slides.
Using these shrouded emulsion tubes on flat bottom slides, the shroud sticks up and holds the slide up (and thus the needle).
The shrouded tubes are designed for curved bottom slides.
Check this out and let us know.
I will apologise in advance for hijacking this thread but my question relates to the above information. The '85 FJ I'm currently working on, has choke issues.
It starts on the choke but after about 20-30 seconds running on it, stalls, it will re-start with a little throttle, choke off but will not idle until fully warmed. Any further use of the choke just stalls it. The carbs are the early model flat bottom slide version but have been fitted with new cut away slides. Who ever did the rebuild left the original flat top emulsion tubes in it. What effect, if any, would this have on tuning the carbs, especially the choke function? I suspect it won't be effecting it but am open to views from others with more experience than me.
Regards, Pete.
Broken float legs glued with epoxy! 0-rings under main jets! broken vacuums etc.
Right now, carbs have curved bottom slides and flat emulsion tubes which i believe they call un-shrouded. Should I change emulsion to OEM shrouded and needles as well?
My set up as of right now:
112.5 main
40 pilot
160 air
3 1/4 turn out
needle clip 3 position from the top
KN filter in the box
F1 double slip on exhaust
Any recommendation will be much appreciated.
I'd send the whole thing to RPM... replace carb bodies that are shot, get all fueling circuits working properly, then tune to their recommendation... the flat bottomed slides can be used and, at least I believe, will give you a more crisp response... I think the curved slides are smoother (boring) in roll on... :bomb: :blum1: :bomb:
Frank
Hi Frank,
Thanks for prompt responce and recomendation.
Since I am out of US, I would rather to work on it my self than sending it for unknown time to RPM.
Thank you