Intake manifolds wet with gas & 3000 rpm idle

[GaryS-NJ]

I'm starting a new thread here hoping someone can talk about what their intake manifolds look like when the carbs are pulled after running.


Mine are wet with gasoline. As if the carbs are just dumping the gas into the engine. and then when I lift and tilt the carbs back, gas pours out the airbox drain (this might have occurred when I turned them on side to remove the throttle cable but I think it happened when I just pulled the airbox drain hose with the carb set still pretty level..


Anyway, I've been battling a high idle issue on this bike I bought not running. Not to go through all my carb cleaning, trouble shooting, and results, but in short, this is a California bike with the pair system removed and T lines off the carb bottoms plugged (used to go to the evap canister). When I run it with the chokes closed, and idle screw all the way down, I get this 3000 rpm idle. and yes, carbs cleaned, pilots cleaned, orifice to pilots clear, pilot/mix ckt clean, mix screws 2.5 turns out, stock airbox, exhaust, jetting, carbs bench synced then mercury manometer synced... I've been doing my testing with fuel delivered via two funnels and extensions to the carb fuel lines..


I'm getting the feeling that there is some sort of vacuum pulling the fuel up from the bowls into the throat but that don't make sense either.


so does everyone's intake manifolds get a puddle of gas at the bottom from idle (or high idle>?)

[maniac1886]

Nope. They should be a bit damp, as if a mist was traveling through them, but they shouldnt be puddled up. I would assume the carbs are flooding. A tell tale sign would be over filled oil. The float bowls aren't shutting off the fuel supply so fuel is flooding up the bowls, through the needle jets, then runs over into the head, and sometimes into the Airbox. The fuel deeps through the valves and into the cylinder causing an unavoidable high idle, then seeps passed the rings into the case, and ultimately into the oil supply. That's the most common issue at least. There's some other possibilities but, check your oil first is it over full, does is smell like fuel?

If so, park it. Gas breaks down the oil and will run the risk of damaging the engine. You don't wanna spin a bearing. I promise.

[GaryS-NJ]

sounds right but

YES, I have puddling. And yes, I changed my oil after I had an obvious float needle sticking.. I've had two funnels feeding the 1/2 and 3/4 separately and on that one, I could see the fuel in clear tubing running down way faster in the 1/2 than the 3/4. And it kept draining even with the motor off. and then that float failed the suck and blow test. I polished the seat and cleaned the needle and fixed it. Since then I'm pretty sure I was doing float bowl fuel level measurements with clear tubing and not seeing the floats leak. And watching my oil level, and monitoring the fuel drink in the clear tubing. And I sniffed the oil yesterday.. And again today I did the suck and blow test with the carbs upside down. Tomorrow I'll turn them right side up, close the floats and do a suck test. yum gas. and then for good measure I'll pull all the needles and polish the seats.

[GaryS-NJ]

I after leaving only the choke circuit as suspect or perhaps the throttle plates not closing up right, I bought a junkyard set of carbs and cobbled some of my parts into them.. runs right now.. thanks all!