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General Category => Yamaha FJ1100 / FJ1200 Running Problems => Topic started by: LimiterBash on March 05, 2016, 02:47:31 AM

Title: massive overfueling
Post by: LimiterBash on March 05, 2016, 02:47:31 AM
Hi all,

I recently had a spark problem and thanks to a member of this forum I have determined it was my Dyna 2000. I have just purchased a new one off ebay. My new problem is when it started running fuel was flowing extremely heavily out of the overflow lines. So Im guessing its a seal or something in the carbys but as I dont know a lot about these I thought I would ask the question. What should I do? Pull them a part?
Title: Re: massive overfueling
Post by: Urban_Legend on March 05, 2016, 03:44:29 AM
It is usually a float or needle and seat issue with fuel that comes out the overflows. They could be stuck in the open position.  First try giving the float bowls at tap to see if it fixes the issue.  If it continues you might have some crud in them. If the bike hasn't run in a while the carbs probably need a.good (as in completely stripping) clean.

Mark
Title: Re: massive overfueling
Post by: Bones on March 05, 2016, 03:48:57 AM
Yes. To avoid further problems later on, pull them apart and go right through them making sure everything is spotlessly clean and in spec. Check diaphragms have no holes in them, get the SS screw kit from Randy that has all the o rings and Allen screws in it and replace everything, check the float tongue where the needle sits isn't pitted and that the levels are correct, make sure the emulsion tubes are clean and are not worn oval and check that the air filter/s is clean.

Basically, do a thorough job the first time and you won't have to worry about pulling the carbs off constantly like a lot of people do to fix minor problems.
Title: Re: massive overfueling
Post by: Alf on March 05, 2016, 03:58:01 AM
Hi

Probably any of the fuel float bowls is blocked in its movement, leave the fuel float valve open and then the carb overflows. Usually It could happen when the bike is without working 1 week or more

There are 2 easy ways to solve that usually works:
1.- With a spanner and a hammer give a series of not too hard bumps to the carb float bowls caps. The trapped float bowl is released
2.- If the previous way don't work, ride the bike, let the engine get temperature and perform 2,3,4 times full throttle accelerations until the red line

Usually this treatment works. In fact, my CBX had the same problem yesterday. I knew a fuel float bowl was blocked because the bike overflowed when the engine was stooped and the fuel key was open and when the engine was running the bike was perfectly from 5.000 rpm and only in 3 cylinder when below

4 times accelerating from 3 to 6 until the redline and the problem was solved
Title: Re: massive overfueling
Post by: oldktmdude on March 05, 2016, 05:28:11 AM
   When you get the carbies apart, replace the "o" rings that seal the needle valve seats that control the fuel flow into the bowls. These "o" rings harden and become brittle over time and will cause the problem that you are experiencing. Go to the "Files" section and read the carbie cleaning write-up thoroughly, most people DON'T get them clean the first attempt, so do yourself a favour and read it carefully and get it right the first time.  Pay special attention to cleaning the choke circuit passages in the float bowel housings. If these are blocked you will have a difficult time starting the engine. Good luck!
Regards, Pete.