Posted April 06, 2003 - 05:34 PM
Posted April 06, 2003 - 07:39 PM
Does it go away when the bike cools down?
If so theres a good chance its the CDI unit
He has killed 2 in 3 years on a YZ426
Might not be, but we chased our tails for ages around the carby path to no avail.
If you have a mate with the same bike do a swap and check it out.
Posted April 06, 2003 - 07:43 PM
I have the same bike and have been going through some problems myself. Check out post (Need help after Mod's). It explains where I started and where I'm at now with my bike. Lots-O-Information in there!
I know before anyone can help they will need more information.
What elevation do you ride at?
What are the exact jetting #'s? I know you say it is stock, but I don't think the clip in the 3rd position is stock on all 99 WR400's. (Is it a US, Europe, Aus, CDN, or ???)
How thoroughly did you clean the carb? Lost any O Rings?
Probably the biggest question is did you clean the accelerator pump real good (were you riding in any water)? Check for cracks on the accelerator pump diaphram. Also check for a cracked slide.
Check into the "Taffy Mod" let me know if you want me to email you pictures on that mod. I haven't taken the time to figure out how to post the pictures (been working on my bike the past few weeks), but I'd be glad to email them to you. I wouldn't do any Mod's like the Taffy Mod until you figure out why it started running bad all a sudden,(mistake I made) but I know the mod is worth looking into.
If you find nothing wrong with the carb, you should probably start running through the electrical tests in the Service Manual. If you don't have a Service Manual I would absolutely get one. It has helped me out a ton.
Keep us posted on the progress!
Posted April 07, 2003 - 06:57 PM
Main-168; Jet Needle-OBDTM; Pilot Jet-45; Pilot Screw- 1 1/2 turns out; Clip position is #4 stock-was in the #3 position when I opened it up.
I didn't mention that it only runs rough when I try to hold the throttle steady between 1/4 and 1/2 throttle. If I accelerate hard through the gears it seems fine until I let off the throttle and engine brake, then it backfires excessively.
I hope this helps. Thanks again.
Posted April 08, 2003 - 06:39 PM
Thanks for helping.
Posted April 09, 2003 - 05:33 AM
Posted April 10, 2003 - 10:06 AM
Any help/suggestions appreciated.
Posted April 10, 2003 - 01:29 PM
Posted April 17, 2003 - 02:20 AM
Posted May 20, 2003 - 03:25 PM