Well guys here it goes!!!My buddy came buy this week end with his 94 FLH and when he pulled out front the carb overflow was pissing gas like no tomorrow!!!It had done it in the past but if he let it run outta gas(the bowl) and then restart it ,it would be fine.Well not this time.So we pushed it into the driveway Sat. afternoon and none to say we didnt ride all week end.And no luck.Now the bike still leaks gas and now wont respond after 1/4 throttle.This is the first time i was unsuccesful at figuring out any mechanical problem on anything!!So here i am and i got a feeling i will be here a lot more often!!!(LOL)Ive fixed riceburners,quads,cars and just about anything with an engine!So im really picking my brain.Ive researched the Keihin CV carbs till no end.I took it apart several times and put it back together.I cleaned the jets,replaced the diaphram,and went over the carb over and over with the OEM HD manual.They only thing i wasnt sure how to do was float adjustment and this can be part of it.He also has a shitty fuel cap that builds pressure and vents once realesed(took caps off).Now it will idle fine,but when i give it gas it dies,sputters and back fires!!!With the air filter off i can see the fuel spraying but i did notice the slide is sputtering up and down.Its not smooth.I took this apart and inspected the boot and cleaned the slide and checked the needle for grooves and all is fine.It is clean but it seem like a vacuum issue.It's like ittotally crokes.Hehad problems in the past with it stumbling and hesitating from time to time but since we took the carb out its 10 times worse.I need help guys.It is jetted with a 45 pilot and a 165 main and the a/f screw is now accesible.Something got disturbed when we took it apart and cleaned it.It starts right up with no problem.It idles fine but when u give it gas it chokes,backfires and wants to stall...Someone must know something i overlooked.This sucks because i never had an issue with a bike and couldnt figure it out!!!Help Please!!!But i did get a goodlaugh outta of it Sunday night when he left to get his trailer.I put it in the street with a Free Harley sign on it and he got really pissed!!!LOL so i owe it to him to fix this!!!! I was debating on sending it out to be rebuilt and modded to correct the common stumbling issue but am at a loss with the whole thing!!!

 

Definitely adjust the float height.

Vacuum line disconnected somewhere? Or perhaps cracked affecting timing advance? Maybe a bad VOES?

 

Two things to check here for that, first is the accel pump, second is the diaphram. The non venting gas cap could be giving you the flooding you describe also as will the float adjustment too.

The diaphram may look OK but hold it up to a bright light and check for tears/holes in it. Also an incorrectly seated diaphram/ top cover will cause the symptoms you describe.

 

This may help https://www.hdforums.com/m_117074/tm.htm

 

I replaced the Accel pump diaphram!!!But not thevacuum piston(rubber boot on top w/ slide).Its like something got disturbed when we took it apart!!!!And now its not getting the right amount of vacuum to pull the slide open!!!The slide should open and stay open smooth as u open the throttle right.So say at half throttle the slide should stay open and be smooth when looking into the venturi when running????

 

I was referring to the slide diaphram in the top chamber that could be the problem, not the accel pump diaphram. If it has any leakage in it whether it be a pinhole or just not installed properly, you will get the problems you describe here. It takes some doing to get the lip to seat properly when reinstalling it into the carb, they seem to grow once removed from the carb. I find that a slight circular motion applying light pressure with the cap will usually "gather it up" and seat it into the groove. If it isn't seated properly, this could be your problem, it will not pick up the slide properly .

 

If you took the emulsion tube out make sure you put the oriface the needle fits in correctly. It only works one way but will fit both. I found out the hard way. If this happens the bike will idle
fine but otherwise run terrible.

 

sounds like the float is water logged and to heavy to control the fuel level

 

From the sounds of it everyone has pretty much it the nail on this one...
1) damaged slide diaphram... needs replacement
2) possible sticking needle in float bowl/ or damaged float (not likely though)... I'd look for gunk in the needle from bad gas
3) possible damaged/leaking vaccum line off the top-back of the carb. Goes to the VOES switch. If this line is disconnected/ not seated properly the bike won't run for sh#t past an idle. The VOES controls the ignition advance.

So between a damaged slide diaphram not letting the carb work, a float bowl flooding, and a vacuum loss... the bike is pretty screwed. But it is all fixable within an hour or so. Get a good Harley manual and good luck...

Swede