I rebuilt the carbs, shimmed the needles, cleaned them a handfull of times. Replaced throttle cables, ensured they arent binding. Bike will start so so easy cold hot, first crank. 12k original miles. I had previously never synced or done really any carb work on big 4cyl 4 carb bikes. Bike sat for a long time. Put a ton of new parts on it. Bench synced the carbs...not very well im sure. Bike runs pretty well i feel the jetting is pretty spot on. No surging sputtering anything pulls well through full rpm range. Ive ridden it a decent amount and i am just not comfortable riding it with the hanging idle. Plugs were not rich. They were kinda lean. Pretty white. I have seen tons and tons of threads on this issue. Idle set at 750-800. Bike will start and idle under 1k rpm, blip the throttle, idle comes down slow, and will not return to ide. Will idle at 2-2200 rpm. Not good. I havent pulled the intake boots, they do not look very cracked but they are original. Im probably looking at a vaccum leak from the boots. Just searching for some advice. I am borrowing a manometer from a friend. Idle curcit is clean. Needles are stock and shimmed, diaphrams are probably original and in great shape. Bike has 4-1 v&h and muffler which probably needs re packed, uni pods. Long post. Figured i would provide the masterminds with all of the details. I forgot what the jetting is i have it written down somewhere but i dont believe the jetting is my issue. Anyways, its a great bike i love it but i feel like im thinking too hard. Has to be vaccum leak making the mixture lean no matter what the mixture screws are. Tried 3.5 out 3 out 2.5 out 2 out 1.5 out. No real change in how the bike reacted but i test rode it like 2-3 mins before turning it off. Just trying to fix the high/hanging idle. Thank you guys. Maybe this thread will provide all the possiblities of a high idle lean condition, i looked at 3 threads and received somewhat different solitions on each thread. Have a good day!
Check your intake boot "o rings". These are a common cause for high idle issues. I recommend replacing them regardless of their apparent condition. They are over 30 years old and will be over-due for replacement. Intake boots could also be cracked so give them a good looking over as well. Don't bother doing the carb sync until you have sorted your idle problem. Make sure your choke system is also returning fully to the off position. Jetting won't be affecting your high idle, but the mixture adjusting screws can but it sounds as though you have already been there. Check your vacuum hose to the CDI unit for leaks and also the CDI unit itself. Suck on the hose to the CDI to make sure there is no damage to the diaphragm. You can safely disconnect and plug this hose if you have a leakage there.
Regards, Pete.
Try with some start spray around intake boot, idle speed will be affected if there is a leak.
oldktmdude - if you suck on the hose for the cdi, should it feel like blocking or should there be constant flow?
Quote from: arendal on August 02, 2018, 12:33:24 AM
Try with some start spray around intake boot, idle speed will be affected if there is a leak.
oldktmdude - if you suck on the hose for the cdi, should it feel like blocking or should there be constant flow?
A constant flow would be a vacuum leak, yes?
FJmonkey - Exactly my though, is it possible to fix vacuum leak in cdi?
Quote from: arendal on August 02, 2018, 12:33:24 AM
Try with some start spray around intake boot, idle speed will be affected if there is a leak.
oldktmdude - if you suck on the hose for the cdi, should it feel like blocking or should there be constant flow?
Spraying start spray on intake boots is not always a good indicator. More often than not it does not work.
You should not be able to suck through the vacuum hose when attached to the CDI.
You do not need the vacuum advance to work in the CDI unit. Mine's been disconnected for over 2 years now. Just be sure the plug the vacuum port on the carbie boot it's attached to.
On my CDI vacuum line there is a oneway valve,(i think) arror pointing toward the CDI. Is this correct?
Quote from: iridewheelies on August 01, 2018, 09:15:58 PM
Bench synced the carbs...not very well im sure.....
Start here^^^
Then set your idle speed to 1k rpm. 750 is too low.
Quote from: Pat Conlon on August 02, 2018, 12:59:04 AM
Quote from: iridewheelies on August 01, 2018, 09:15:58 PM
Bench synced the carbs...not very well im sure.....
Start here^^^
Then set your idle speed to 1k rpm. 750 is too low.
I watched a couple vidoes on bench syncing but however i did not use a feeler gauge. I kinda eyeballed it to where the butterflys were generally open the same amount and they would all open in unison. Any idea what size feeler gauge would be a good start on a bench sync? First time for everything right. Will check vaccum line going to cdi. Pulled off one of the intake boots. They are actually in great shape. The allen head fasteners were definitley "factory tight" inspected the o ring it was flat, fuel had seeped through and was outside of the o ring. My dad has a shop and works on everything. Matched the o rings. I feel like once the bike is back together it will run better than ever. Thanks guys. Just need to do another bench sync. Keep in mind that it did run pretty well just had the hanging idle. Ill do some more reading and will use a feeler gauge this time. Also, which carb should i begin with? Is number one the carb on the left (clutch lever) side ofnthe bike? Also, the bike has a pretty scary speed wobble. Ordered front wheel bearings, but i feel that may not fully cure the issue. 60-80 percent sure the anti dive is still functioning. Thank yall
Amd by speed wobble i mean it is solid with both hands on the bars. One hand off it begins to shake progressivley to cause a nasty terrifying tank slapper if u do not put more pressure back on the bars. 2 hands on 1 hand off the bars is fine. But releasing pressure will cause it to shake, almost as if the forks are out of allignment. Eventually i am going to do a full r1 front end swap so i would rather not throw money at an old set of forks
110% of the time, for me, a front end wobble is a worn front tire.
Does your tire have a center tread groove?
For synching, the #2 carb from the left (while sitting on the bike) is the reference carb. Match #1 to #2, then match #3 with #4. Use the center sync screw to match the 3/4 pair to the 1/2 pair.
The front tire is probably a little old, still has pretty good tread. Thanks for the sync advice, but how large should the opening be on the butterflys? Or does it more so matter about how equal the opening is? Thanks
For the wobble; Over all the years i have been on my fjs i only had wobble 3 times all on my fj1100 2 times im convinced it was because of heavy loaded luggage bags 1 st time i was catching up with my friend on a long trip going way to fast into a righthand corner that surprised me being more and more curved i was going into opposite lane and right at the shoulder of the road i got a highside almost throwing me off i got hanging on the side of bike lucky as i was the bike tracked back into the road and wobbled violently with me ending up lying flat on the bike with my legs straight bacwards the wobble stopped (probably because i was lying down) i stopped and had to smoke 2 cigarettes to ease down.
Second time also had heavy luggage bags going fast i hit a bump starting wobbling i lean forward over the tank and it stopped right away.
third time i had no luggagebags but a passenger i was riding kookalao speed on the freeway (young and dumb) suddenly it felt like the road was real slippery the bike started to wobble real bad my friends feet coming up under my armpits i was thinking that if i brake now we will go down hard so i did nothing only eased very slow on the throttle until the bike stppped.The reartire had puntured flat.many times im thinking what if it was the front tire...
Im no expert butThe list of why a bike wobbles can be very long but i think wrong suspension setup wrong tire pressure/worn tires steeringhead bearings is some of the most common.
Always remember if you get a wobble lay down forward and it will stop!
I think the fj is a very stable bike newer had wobble on my fj1200 (no luggage bags)
About the carb sync i think it not possible to get them synced outside the bike.Bench sync is only for get the engine running.
Well i replaced the intake manifold o rings, lubed the throttle cables, and attempted to sync the carbs. I borrowed my buddys gauge set, and i set them all to zero. No matter what i did i couldnt get number 2 carb to the green area on the gauges. I just ended up fucking the butterflys up and had to take the carbs off and re bench sync it. Got that done got the bike running and idling at 1k. Go for aride around neighborhood. 5 mins later, bike is idling at 2k again. Not sure what to do. Really fed up with this bike it will not run right. Ive spent so much time on this turd
So, 5 minutes later after it is more fully warmed up, the idle is high?
Turn the idle down now that it is fully warm, and use the fast idle while it warms up. It is not a modern OEM fuel injected engine with a computer controlled idle speed valve — seems like normal behavior to me.
Quote from: FJ_Hooligan on August 03, 2018, 12:41:32 PM
110% of the time, for me, a front end wobble is a worn front tire.
Does your tire have a center tread groove?
For synching, the #2 carb from the left (while sitting on the bike) is the reference carb. Match #1 to #2, then match #3 with #4. Use the center sync screw to match the 3/4 pair to the 1/2 pair.
Yea it has a center tread groove. Im not worried about how it rides if i cant get it to idle at the set idle position... pretty discouraged. The o rings i matched looked a little fat but they did flatten up as i tightened the intake boots and should not be leaking at all. Intake boots look great and are not hard. Still don't understand why she wont idle at 1k, besides the carbs not being balanced. Which i am going to clean up my work area, and try again. one noticable issue, when attempting to sync an hour ago all needles were in the area of "leak at manifold or heat riser/late valve timing" nowhere near the green area. I didnt exactly have the sync flat but it wasnt hung up in the air either. First time syncing so yeah im a noob. But i still dont feel like a sync will cure that 2k rpm idle..... should i try ordering o rings that are advertised for these intake boots? The ones i got are the exact same size as the old ones.... could the choke be leaking at the plungers? Might pull the diaphrams loose and see if the choke is closing all the way.... are my floats letting too much fuel in? They are at 21-22mm i didnt even adjust them...
Quote from: fj1289 on August 05, 2018, 05:28:17 PM
So, 5 minutes later after it is more fully warmed up, the idle is high?
Turn the idle down now that it is fully warm, and use the fast idle while it warms up. It is not a modern OEM fuel injected engine with a computer controlled idle speed valve — seems like normal behavior to me.
Thanks for the quick reply. Will try that and let you guys know.
Well i think the high idle is now fixed. Rode it around till idled at 2k, and reset the idle to 1k. Going to ride around town now and see how itll ride outside of the neighborhood. Thank u, i didnt really think of that. I am really mechanically inclined on many and most engines. But a bank of 4 carbs is still pretty new to me.
Looks like turning the idle down when it was "fully warm" and idling at 2k was the fix. I was just over complicating it. Now to retry syncing the carbs. I have the screws at 3 turns out, but it seems kinda sluggish. So before i hook up the vaccum lines, set the gauges to zero right. Should i try to make #2 carb in the green normal zone? Or just base and balance the other carbs off of what the base carb is reading. Thanks again guys. I just bought a 2005 suzuki z1000 for 1000 bucks, and the efi is gonna be nice, but i do like the feeling u get from making a gem like the fjs run like a dream. Just easy for me to get discouraged. Im 18 and havent been working around 4cylinder 4 carb bikes all my life. Lol :dash2:
Turning the idle adjuster down will increase the vacuum you see on carb #2.
The adjuster was holding the #2 butterfly open too far.
I would not worry too much about where the needle sits ( green zone or otherwise) as you are trying to get all the other carbs (1,3 and 4) to match up to the number 2 carb. I know you have been having an issue with the revs hanging, but for syncing the carbs, it is actually easier to get a steady read on the vacuum gauges with the idle turned up a bit ( between 2k and 3 k rpm) don't forget to have a few fans blowing air on the motor. Hope it all works out for you
Mark
This might sound funny but when you are syncing the carbs with a vacumgauge you are using the 3 scews in front of the carbs and not the mixture screws on the carbs right?
That is correct.
The vacuum balance screws are not in front of the carbs. They are on the throttle shaft beside the carbs.
Quote from: oldktmdude on August 01, 2018, 10:16:28 PM
Check your vacuum hose to the CDI unit for leaks and also the CDI unit itself. Suck on the hose to the CDI to make sure there is no damage to the diaphragm. You can safely disconnect and plug this hose if you have a leakage there.
Regards, Pete.
Hey Pete, where is the CDI unit, and the vacuum advance hose? I think I'm chasing down a vacuum leak as well.
Quote from: aigram on August 27, 2018, 11:54:55 PM
Quote from: oldktmdude on August 01, 2018, 10:16:28 PM
Check your vacuum hose to the CDI unit for leaks and also the CDI unit itself. Suck on the hose to the CDI to make sure there is no damage to the diaphragm. You can safely disconnect and plug this hose if you have a leakage there.
Regards, Pete.
Hey Pete, where is the CDI unit, and the vacuum advance hose? I think I'm chasing down a vacuum leak as well.
The CDI unit is located under the left side cover, attached to the battery box. The vacuum hose is connected to the inlet rubber on number two carb and runs to the CDI unit.
Hey Pete and Alex, I seem to recall that when Yamaha went to the digital controlled ignition (DCI) starting in 1989 they took the vacuum advance out of the ignition box and used a separate stand alone sensor located under the right side of the fairing. The vacuum hose goes from the #2 carb to this remote vacuum sensor under the fairing. The vacuum sensor has wires that send the advance signal back to the ignition box.
I know for sure my previous '92/93's were this way...so I think it started in 1989.
The older '84 to '87's that have the analog transistor controlled ignition (TCI) do have the vacuum advance sensor built into the ignition box, so on those FJ's the vacuum hose runs from the #2 carb to the ignition box.
To test the vacuum advance sensors all you do is unplug the vacuum hose at the #2 carb and suck on it. If you can draw air, then the diaphragm is shot, or you have a leak in your hose. The hose is a easy fix, but the diaphragm.....it depends.
The '89-95 FJ owners are lucky with having the remote vacuum sensor....just order a new sensor. See #24 on the part list: https://www.partzilla.com/catalog/yamaha/motorcycle/1989/fj1200w/electrical-2 (https://www.partzilla.com/catalog/yamaha/motorcycle/1989/fj1200w/electrical-2)
The '84-87 guys with the TCI built in sensor are SOL. They have to get the ignition box...and no new ones are available.
All is not lost. The vacuum advance has no performance benefits. Just cap off the #2 port and call it a day.
http://www.fjowners.com/index.php?topic=11690.0 (http://www.fjowners.com/index.php?topic=11690.0)
If the idle /Revs do not change when adjusting any of the 4 Mixture Screws in or out ,,"""Your Carbys Jets are Blocked """ Strip down and clean all Jets and fuel passages ,, You Balance the Carbs with the 3 Phillips Screw,s that are attached to the Butterfly Shaft ,,It does not matter what the 4 vacuum readings are , as long as they are all the same ,,,
Quote from: Pat Conlon on August 28, 2018, 01:27:07 AM
Hey Pete and Alex, I seem to recall that when Yamaha went to the digital controlled ignition (DCI) starting in 1989 they took the vacuum advance out of the ignition box and used a separate stand alone sensor located under the right side of the fairing. The vacuum hose goes from the #2 carb to this remote vacuum sensor under the fairing. The vacuum sensor has wires that send the advance signal back to the ignition box.
I know for sure my previous '92/93's were this way...so I think it started in 1989.
The older '84 to '87's that have the analog transistor controlled ignition (TCI) do have the vacuum advance sensor built into the ignition box, so on those FJ's the vacuum hose runs from the #2 carb to the ignition box.
The '89-95 FJ owners are lucky with having the remote vacuum sensor....just order a new sensor. See #24 on the part list:
Thanks Pat, I do know this information, I was referring to it as a"CDI" unit as not to muddy the waters. CDI is a common term used to identify many ignition systems that are not strictly "CDI"
Regards, Pete.
Yea Pete, I hear ya, TCI, DCI, CDI, whatever... my point was the vacuum line on the '89 does not run to the ignition box like the earlier FJ's.
The later model FJ's in Australia don't have that vacumn line Pat, I know my 93 hasn't got it, must be an Americian emissions thing.
Interesting, yet another difference with the AU vs US bikes.
Do you know if the early FJ's (84-87) sold in Austrailia have the vacuum line to the ignition box?
Quote from: Pat Conlon on August 28, 2018, 12:57:51 PM
Yea Pete, I hear ya, TCI, DCI, CDI, whatever... my point was the vacuum line on the '89 does not run to the ignition box like the earlier FJ's.
Pat, does this set up on the later models, perform the same job as on the earlier models? Just curious. Mine has been disconnected for a couple of years
with absolutely no indication of it being so.
Regards, Pete.
Pete, yep, it's an emissions feature, nothing to do with performance.
Throttle plates open = low vacuum = no advance.
Throttle plates close = high vacuum = ignition advanced
This is the early 84/85 FJ1100 timing curve posted just to show the example....I'll try and find a late FJ1200 timing curve.
(http://i949.photobucket.com/albums/ad337/craigo987/FJ11001984ServiceManual269.jpg)
I've had mine disconnected for years, no problem at all, I don't miss it..
One thing I did notice, when I had the vacuum advance connected and I would snap close the throttle, my bike felt like it wanted to speed up, that was the advance happening. Now, with it disconnected, my bike slows down on the engine compression, as it normally should.
RPM Randy mentioned several years ago that the Legend/T-Roadster racers purposely disconnect the vacuum advance just for this reason.
When rolling off the throttle setting up for a corner, they wanted their race cars to slow down, not speed up.
Quote from: Pat Conlon on August 28, 2018, 05:11:10 PM
Interesting, yet another difference with the AU vs US bikes.
Do you know if the early FJ's (84-87) sold in Austrailia have the vacuum line to the ignition box?
Pat
The JDM FJ's does not have it either.
But,with the carbs we saw there are quite a lot of differences
Hannes
Good to know, thanks Hannes!
Speaking of JDM and the power restricted FJ's (like the Swiss bikes) what I noticed was a different, less aggressive ignition timing curve on the power restricted models.
iIRC it actually had a dip programmed in the timing at ~6k rpm.
This was, of course, built into the TCI/DCI ignition box, so the only way to defeat it was to get an ignition box off of an unrestricted FJ.
We ought to compile a list for the Files noting all the differences in our FJ's sold thru out the world.
Like, in Austrailia, the FJ's did not have the side stand switch, the JDM/AU bikes have no vacuum advance, all the crap the JDM/Swiss/French bikes have for power and speed restriction, all the other FJ's except the USA bikes, get the 'flash to pass' headlight switch.....things like that...
All this stuff gets confusing (to me) to remember.
If we write it down and have it in the Files, it will be easy to look up in the future.