03 Barely Starts and Idles at 1/2+ Throttle
Posted June 28, 2006 - 06:02 AM
DESCRIPTION (03 WR450):
Bike was running fine and starting fine (start right away with e-start and 1-2 kicks to start). No problems in the past either. Then I started it and it was idling poorly and stalled as I tried to take off. Then I wasn't able to start it. When kicking it, it would barely start and stall within 1-2 seconds. I generally I try to kick from TDC, so sometimes, after a good kick, when I go to slowly move the engine back to TDC, the sligth movement of the kickstart would cause it to kick back and and almost start. Also, it backfires sometimes while kicking.
WHAT I HAVE DONE SO FAR:
The only changes from the time the bike was running well to when it starting running poorly was putting in a new filter which I think I may have over oiled. So I did the following:
- Put the "dirty" filter on with which the bike ran well previously and it didn't really change anything. Although I was able to start it on occasion (after 15-20 kicks) and would only idle if I held the throttle about 1/2 or more.
- Took the carb off and took out all the jets and cleaned with carb cleaner to make sure no carb circuits where clogged (i.e. as I sprayed cleaner in one orifice, I looked to make make sure it came out where it was supposed to). I didn't touch the slide or TPS though. Put the clean carb back on and similar situation, although it started a bit easier, it wouldn't idle unless the idle screw was fully turned in. I tried to ride it and it would stall as soon as I got off the throttle (even with high idle). I tried with TPS connected and disconnected. No noticeable change.
- Knowing that 03's have the woodruff key issue, I checked if the flywheel timing mark lined up with the cams and they all lined up, but I still thought it may have gotten knocked out of time, so I pulled the flywheel and the key is still intact. I replaced the key, put the flywheel back on. I can barely start it now, but behaves as before, starts for 1-2 seconds and dies. Runs only if held at 1/2 throttle or more.
- Put in new plug. Same problem.
- Drained gas and put in new gas. Same problem.
- Disconnected TPS. Same problem, although seemed a bit easier to start, that is instead of 15-20 kicks, it was 10-15 kicks, but still wounldn't idle unless I held the throttle 1/2 or more.
- I'll check my valve clearance, but I doubt that's the problem since they were in spec last time I checked them and I only rode about 2-3 hours since I checked them and they only where out of spec once, which was after break in.
- Check throttle slide for cracks (note that when I cleaned the carb, I didn't touch the slide. I heard similar symptoms from older WRs which had issues with cracked slides).
After the above steps, I'm at a loss. I'm doing to have to start going by process of elimination, but at the moment, I suspect an electrical/ignition problem.
Anyone has some insight, ideas, things I should check?
Posted June 28, 2006 - 07:37 AM
1- Borrow a friends carb from a 2004 YZ450 in order to see if it is carb related.
2- Borrow a friends CDI from a 2004 YZ4540 to see if it's an ignition/CDI issue.
Does anyone know if I can simply plug the YZ CDI on my 03 WR? The 2003 & 2004 WR list the same P/N for the CDI, but the YZ lists a different P/N from the WR and also changed from 2003 to 2004. Does anyone know what the second and third digits of the P/N mean? I want to try a 2004 YZ CDI on my 2003 WR.
2003 YZ450F 5TA-85540-00-00 C.D.I. UNIT ASSY
2004 YZ450F 5XD-85540-00-00 C.D.I. UNIT ASSY
2003 WR450F 5TJ-85540-00-00 C.D.I. UNIT ASSY
2004 WR450F 5TJ-85540-50-00 C.D.I. UNIT ASSY
Posted June 28, 2006 - 07:50 AM
Posted June 28, 2006 - 12:51 PM
Posted June 28, 2006 - 01:33 PM
Posted June 28, 2006 - 06:54 PM
Posted June 28, 2006 - 10:45 PM
Posted June 29, 2006 - 04:55 AM
Thanks for the posts guys!
Posted June 29, 2006 - 04:03 PM
Awsome, finding the problem. F'me, I'd never have picked that one.
Thanks for the input guys. I was actually going to install a friends carb to see if it solved the problem, allowing me to isolate the problem, but since I had already thoroughly cleaned the carb, I was going to check a few other simple things, and surely enough, it was a faulty kill switch! The intermittent starting and idling at high RPM only really threw me, but it was the kill switch!
Thanks for the posts guys!