Carb Overflow Issues

[Slick]

I apologize in advance for such a long post. Lots of information and also I am new to this forum.

Intro:

I have a pretty stock '85 FJ1100, 16k miles, with a V&H 4-1 exhaust. The bike is in great shape, just had a paint job with hand laid pin stripes. I got the bike for cheap because it needed a few things like tires, brakes, and new bolts here and there. I have rode it about 10 times since I got it 5 months ago. When I first got the bike it would not stay running. I cleaned the carbs and the bowls were covered in bright orange sandy stuff( I assume rust). I cleaned the carbs with carb cleaner, and put new plugs in. The bike ran great(to me at least) except for a rough idle, and it would stall if you snapped the throttle open from idle.

Just recently I started getting the bike ready for riding now that winter is over. I tried to start it and it seemed like the problem was back again. I took the carbs off and once again orange sand, but no where near as much. So I cleaned the carbs and put in new plugs, except this time I cleaned the carbs more thoroughly . Every jet,screw, or hole accessible from the bottom of the carb was removed and cleaned. I did not remove the air/fuel needles but did shoot carb cleaner through every hole I could find.

Problem:

The bike now runs great, smooth idle, snappy throttle response...except...After riding, about 2hr later, the carbs start overflowing. And on cold starts the bike backfires and pings until warm. Then she runs like a champ for the rest of the day with a beautiful idle and good power.

So I assume everyone is going to be pointing me to a carb or peacock rebuild. I am pretty sure the vaccum is not working on the peacock or the carbs wouldnt be getting fuel to overflow?
*Should there be enough pressure on the floats to not let fuel in even if the peacock is not working properly?
*IF I do a basic carb rebuild, what would need to be done after? ex Sync Carbs, Tune them?
*What is a good idle on these stock motors warmed up on a warm day(75F) running 93 octane.

I know motors, but more so car motors. This bike thing is new to me other than the dirt bikes I had as a kid. Just trying to get a feel for all this new equipment.

[Dan Filetti]

The rust in the carbs is almost certainly coming from rust in the tank, flaking off and making it into the carbs.  This is not a simple thing to fix.  Some folks have used a product called 'Cream' to coat the tank.  Others think this is a bad idea.  Some folks have had some luck taking the tank off, emptying all of the gas out, putting in some small rocks or other abrasive material and shaking the tank every which way for a crazy-long period of time to 'sand-off' the rust.

You will have to solve the root problem or continue to have carb issues -seems to me.

Good luck,

Dan

[racerman_27410]

I would definitely clean and thoroughly inspect inside the gas tank before touching the carbs again.  

its pretty common for first time carb cleaners to have to go back into the carbs a second time... dont worry it's a right of passage in the world of FJs.

consider it quality time well spent!

checking the valve clearances would be the first place i would start tuning.  Sometimes the valves will tighten up and thats not good.... once properly set though they can go a long time without needed further adjustment.

Its always good to have that baseline written down for future reference.

You will also benefit from some form of carb synchronizer....   either home made or store bought.

i prefer the morgan carbtune as it doesnt have any liquids to spill or get sucked in the engine during the balancing process.


these bike really respond well to carb synchronization....

i usually have my warm idle around 1000 RPM  they will rattle if you idle on down too much below  900 RPM or so.

the float needle valves should hold against the pressure from the tank if in good nick but ideally you want the petcock to positively shut off the flow of fuel to take as much pressure off as you can.


KOokaloo!

[andyb]

Frank's right.

Get that tank a good looking into before going too far afield.

Go here and print it out.  That'll be your bible for cleaning the carbs very completely.  While you're in there, write down the jets, needle positions, etc etc, eventually you may want to refer to that info.

Then check the valve tolerances. 

And then set the synch.  The morgan carbtune is a damned nice little instrument, albeit a pinch pricy, but it can't spill, which is golden. 

Idle speed definitely needs to be a four-digit number.  I like mine up a bit higher still, 1150-1200ish.

Entirely probable that you've got some issues in the float needles, petcock, and possibly even venting areas (including the gas cap).  Float needle seats are NOT welded in, though they may feel like it. 

[Slick]

There is some rust in the tank that I can see. I was looking into syncing the carbs before and was wondering what a shop would charge me before buying my own meter. The Tech said as long as the air/fuel mix was never touched they shouldnt need syncing. He was like hey we can do it for you, but I really dont think it needs to be done. So I left it at that. I'm going out for about a 2 hour ride in like 15min, I will see how things go. This bike may need work, but she is still a joy to ride

[Dan Filetti]

Frank's right.

Get that tank a good looking into before going too far afield.

Frank's right?  Frank's right?!  What am I? -Chop liver?  I posted this advise before Spanky.  Sheesh, a guy get's no respect around here...



Dan

[racerman_27410]

dont take your bike back to that shop /mechanic   

Synching the carbs has nothing to do with the mixture being touched or not..... it has everything to do with all four carbs mechanically working together for maximum kookaloo and minimum engine vibration

i synch my carbs every spring and i can tell a difference each time ..... it only takes them being off a small amount to make a huge difference in driveability.


KOokaloo!

[simi_ed]

Dan, you'd get treated better if you actually OWNED an FJ  :

[Yamifj1200]

"The Tech said as long as the air/fuel mix was never touched they shouldnt need syncing."


Your tech is an asshat!!!!  Sounds like he has no clue as to what synching a set of carbs is. Buy a manual and learn to do it yourself. Or meet a local FJ owner who has some knowledge to help you. Your mixture screws have nothing to do with a set of carbs being in sync!!!

Eric M

[Slick]

Well I'm glad I found you guys because I am left in the dark otherwise.

I just got back from a nice ride..except...I rode for about 2hr straight, Opening her up here and there, a red light or two. And then she started acting a little funny when I came to a stop to use my phone. It seemed as if the motor was loading up, and it stalled. It started right back up, but was not idling properly, kept pinging and missing. But as soon as I pulled out onto the road, no problems unless I came to a stop again. So I made it to pick up the woman, and while I was waiting I turned the bike off. It sat for about 15min, and then would not start. Just kept turning over as if no spark. I called for a tow(gotta love free roadside assistance) and while I was waiting, about 30-45min, the bike must have cooled down because she started. She ran fine all the way home (Highway riding) and then when I got home I noticed a little bit of smoke coming from the carb area. I have not looked into that yet because my first thought was, let me ask the guys.

Please point me in some direction. I dont understand why I have all these starting/idling issues. I read through the carb tuning bible and the bike fits every recommendation in each step as far as top end power, low end power, 3rd gear from 3k-7k rpm, etc. So how could all of these things be running right, yet I have so many issues? Does this bike REALLY get any faster? OMG I wouldnt know what to do with all the power when its running right, if this would be considered running bad........

[andyb]

If it's running properly, a bounce on the throttle at 3k in first should easily lift the front tire.  Using the top third of the tach should hurt your shoulders.  Unfortunately those are the things that are easiest to fix.  Improving low rev drivability is probably the most finicky bit.

Sounds to me like there's crap in at least one of the carbs still, there's a problem at the float needle area, there is a lack of venting in the gas cap, and possibly a little adjustment needed on the idle mix.

Doesn't really make any difference, if you're running rusty shit through the bike, it'll never run the way it should. 

[FJmonkey]

If it's running properly, a bounce on the throttle at 3k in first should easily lift the front tire.  Using the top third of the tach should hurt your shoulders.  Unfortunately those are the things that are easiest to fix.  Improving low rev drivability is probably the most finicky bit.

Sounds to me like there's crap in at least one of the carbs still, there's a problem at the float needle area, there is a lack of venting in the gas cap, and possibly a little adjustment needed on the idle mix.

Doesn't really make any difference, if you're running rusty shit through the bike, it'll never run the way it should. 

Gas cap vent problem happens while under load, vacuum in the tank, limits what years will do this with a clean fuel filter. Seems like a stuck float, runs great while consuming fuel and floods while sitting still. That is my $0.02. Any fuel under the bike after sitting?

[Slick]

Tank will drain overnight. Last night I played with the valve, I changed it from primary to halfway in the middle of the other setting, I dont know the point of the other setting but it didnt leak. But before I ever did that, nothing stopped it from draining the whole tank

How do I clean this tank of rust? Please dont tell me I have to get a new tank because this one was just painted to match the bike. I would hate to loose this fresh $1600 paint job. Can someone give me their best recommendations and the cost...The rust is visible when looking in the tank from the cap. I cant tell how bad it is else where. Also where can I get a gas cap? Or is that a new tank?

In addition to my last post. The bike was running REAL HOT on the way home, and it was only 68-70F outside.

[FJmonkey]

Tank will drain overnight. Last night I played with the valve, I changed it from primary to halfway in the middle of the other setting, I dont know the point of the other setting but it didnt leak. But before I ever did that, nothing stopped it from draining the whole tank

How do I clean this tank of rust? Please dont tell me I have to get a new tank because this one was just painted to match the bike. I would hate to loose this fresh $1600 paint job. Can someone give me their best recommendations and the cost...The rust is visible when looking in the tank from the cap. I cant tell how bad it is else where. Also where can I get a gas cap? Or is that a new tank?

In addition to my last post. The bike was running REAL HOT on the way home, and it was only 68-70F outside.

You have options to keep your tank and $$$ paint job. Others will chime in on how remove rust as well as possibly coat the interior to prevent future rust. I have no knowledge or experience on this as I live in SoCal and rust is banned from the state. It simply does not exist in this desert climate. Like trying to convince people living on the equator that water can fall from the sky in frozen flakes. Rust is old wives' tales and rust prevention is snake oil. A good fuel filter will be your friend till you get the rust sorted out.

[Brook]

....... I used... por-15... to seal the inside of my tank,.... No more carb. problems    LOL