New discovery on slow to idle.

[i-paint]

Hi, This is an onging problem. I had a previous post and thought the problem was mechanical but it wasn't. My engine is slow to return to idle. I have no leaks, mixture is not lean (rich if anything-plug is black), changed carburetor, took breather off slide works fine. What I have discovered is the engine idles fast when I stop. If I stop the engine and restart it, it idles fine. Again when I run it at open throttle and stop again it idles fast. Can't figure it out. It is something that is holding the throttle more open after running. Head gasket maybe? Checked head bolts not loose. Thanks in advance,
i-paint

 

[2door]

Paint,
Are you certain your throttle cable is letting the carb go back to the idle position. It almost sounds like there could be a bind somewhere that is keeping the slide pulled up a tad and causing the high idle condition. I'd start with your twist grip and cable before I got too deep into the engine. Keep us informed.
Tom
Easy Ridin'

 

[i-paint]

2door, Yes the slide returns to idle just fine. I remove the air filter and watched it several times. In fact it is a new Dellorto carb and it idles beautifully when you start it. It is during riding that it idles higher. If you turn the engine off and restart it, the idle returns to normal. The Dellorto has the same problem the Chinese carb has.

 

[Bikeguy Joe]

Fuel foaming in the float bowl, causing a lean condition. Then when you ride it, the plug blackens up?

 

[i-paint]

Bikeguy, What is the solution? Thanks

 

[Motoschwinn]

I found installing the Sick Bikes air filter helped 100%. I think due to the sloppy fitting and workmanship of the original plastic carb cover. The SBP has a much better seal. My bike really idles like it should.

It's made a BIG difference!

 

[hill climber]

i think bikeguyjoe is on it, fuel foaming in carb because of vibration.

 

[TexasDav]

I had the exact same thing on mine and it was a bad intake gasket. It looked good but did not pass a starting fluid test, spayed on the intake. That fixed my random fast idle.

 

[i-paint]

TexasDav, I have mine sealed on both sides. I did the spray test on the gasket and carb inlet also. Neither indicated a leak. It may be the fuel is foaming but it runs great
(38mph) and idles great when you first start it. This engine vibrates less than any I have owned. Also the plug indicates it is rich. Beats me!!! (so far)
Thanks,
Larry