Hey guys, my first post on this forum. I just acquired a 1999 WR400 a few weeks ago, and am in the process of catching up on some maintenance, road registration, etc. I currently own a 1981 CB900f in addition to the WR, and I used to own a 1979 XR250. Yes, the XR was MUCH less finicky about jetting. I never had to mess with it.
My biggest issue right now is the fact that I can't get it to idle. I have read all the pinned posts on jetting, and have also searched for the answer. But the odd part is that any change I make doesn't seem to help.
I have gone through the carb twice now to make sure it's clean. As best I can tell there aren't any vacuum leaks, either. All jetting is stock, but the p/o removed the airbox cover and decorked the exhaust (I'm not sure if it's an XR baffle or what, but it's pretty loud).
The issue: it will not idle smoothly, the revs hang a little bit, and the pipe glows red after I take it for a ride up the road.
What I've done: cleaned the carb thoroughly, installed leaner pilot jet (42 from the OEM 45), new air filter, new spark plug, disconnected TPS (no difference, just less precise throttle response). I have also disconnected the accelerator pump simply to rule it out (to me the worst is that it doesn't idle smoothly, and off idle response, 1/8th turn throttle, seemed rich. However, disconnecting the pump didn't help).
Before I changed the pilot jet it didn't need the choke to start when cold. Since I leaned the pilot jet it now needs the choke when cold. So maybe I'm on the right track. However, I don't think it has helped my idling issue. If it did make any difference, it was very slight.
It will idle if I turn the idle speed up. But then as the pinned post in this section says, you have to deal with the rev hang. I have attempted to adjust the pilot screw, but it has made no noticeable difference. It makes the problem a little worse if I close it all the way, but anything from 1/2 - 2 1/2 turns out makes no difference.
Anything I'm missing? I appreciate in advance any help or direction
Edited by RedTravis88, April 03, 2015 - 04:31 PM.