Hey guys, Im lookin for a few ideas on this before I go taking things all apart again..

My bike (340cc's) has been sitting for about 10 months, I use fuel stabilizer.. Well today I went to start it and no go.. So I take the carb out (FCR35) disassemble most of it, clean off some light depositis with carb cleaner and put it back together. No extra parts when I was done. Cleaned and reoiled the air filter too.

Now when I last rode it, it would start right up and idle no problem. Now, It will start with throttle application and will run if I keep the revs above 3k. If I let it drop below that or if I come off the throttle, it will die, not even a chance at idling. I have my idle adjust screw all the way up.

So what could it be?

I checked, all the boots are on right, no air leaks..


Thanks for your thoughts guys!!

~Steve

 

Clogged pilot jet ?

 

Ahhh, I remember the feeling of frustration you're going through with this. Everyone's immediate assumption is that there is not enough fuel - which is understandable and logical. Given you have just cleaned it though, one would hope the pilot jet is not clogged.

First question: have you put fresh fuel in the tank, and have you checked the spark plug to make sure it is in decent condition? By doing both of those you limit the potential issues to the carb (for the most part).

Is there a smell of fuel once you have managed to start it? That would indicate the pilot circuit is too rich, hence the need to turn the idle right up, and the fact that the bike will run when the throttle is open enough to start engaging the main fuel circuit (slider is open to allow more air to be sucked in and get the air/fuel mixture closer to a ratio that allows the bike to run.

I would advise turning the air/fuel screw all the way in till you can feel the spring is totally compressed but not over tightened, then dialing it out to 1.5 turns out again (just in case you didn't do that properly when you first reassembled it). Much easier to do this with the carb off the bike IMO. Before you put the carb back on the bike I would advise unscrewing the idle screw till the slider is properly seated too - otherwise you might get an almighty fright when the bike revs it's guts out once you have started it

From there it will be a case of fine tuning the a/f screw to get the right idle.

Also, are you sure you put the needle back in on the same clip position? This should not affect the idle circuit at all, but may affect the a/f mixture in the first stages of the throttle openning.

As a matter of interest, can you tell me what size pilot and main jets you are running?

Let us know how you go.

 

+1 Most likely still something clogged up in the pilot circuit.

The spray carb cleaners don't really do that great job in cleaning out tiny passages that are already clogged.
Remove all the jets and the pilot screw, clean them individually with cleaner + compressed air. Then same with the carb body.
Make sure all jets and orifices are clear and open. Then reassemble.

Better than the spray cleaners is the kind that you dunk the parts into.
That does dissolve deposits much better.

Undiluted Pine Sol works also great! Let the carb parts soak in Pine Sol over night and rinse with hot water. Then blow dry with compressed air.

--
Mikko

 

Idle MIXTURE SCREW all the way up?


Idle SPEED screw all the way up?

You should be able to squirt carb cleaner through every jet or hole in the carb and it will come out some where. Wear good eye protection. Carb cleaner is nasty. Use the straw that comes with the can to direct it.

David