[markonhisbike]

Hello, I'm new to the group and hoping one of you guys or girls can shed a bit of light on a strange problem I've got with my crf.
So: it's a 2005 Crf450x I've had for years and it's started running on when I let the throttle off, as I come to a stop and pull the clutch in then actually stop, the engine is revving higher than it does at idle and then 4 or 5 seconds it drops down to the correct idle speed, also if I'm doing a tricky climb and need the engine to chug me up a rocky section it sometimes revs slightly on its own and tries going without me, but not every time!! it does it probably 50 percent of the time. The bike starts really well, pulls well and otherwise fine. I thought it might be taking air in somewhere so put a genuine carb kit on making sure it's all sealed, also I've been through some very deep water when out off-roading and it didn't miss a beat.
Has anyone got any ideas???

Thank you
Mark

[Back2-2]

Hello,
Your first thought of an air leak was very valid. What you have described is usually either an air leak between the carb and engine. Rubber boot, manifold flange, carb cap or throttle cable inlet. Can also be the hot start lever cable fitting on the carb top.
Other simple items that can cause that symptom is throttle cable catching from strands of the cable on either end of the cable. Even a throttle tube bind can go that and hold the throttle open slightly at times. One other item but rare is a sticking throttle slide from gunk build up.
Air leaks can be traced with a can of ether sprayed all around suspect areas while the engine is running and listen for the idle to raise.

Hope that helps and gives you some things to look for.

[Leardriver]

A partially clogged passage or pilot jet can cause a lean hang.