98 wr400 plug troubles

2 replies to this topic
  • moe396

Posted April 12, 2006 - 07:12 PM


My 98 wr400 had a low end bog, so I cleaned the carb, installed a quickshot acc pump cover and installed a new plug. Rode the bike for about 3 hrs. Bog seems to be gone but the plug took a crap and the bike wouldn't start. Backfired after many kicks. At one point I'm sure I gave it a shot fuel, this could have caused the backfire but not sure. Installed a new plug and rode for 30 mins or so and now the bike breaks up like the rev-limiter is kicking in. Not all the time just once & awhile. If anyone can help please do. Also, I have looked for the gray wire on this bike & I can not find it. Am I blind or does the 98 not have the gray wire. I bought this bike used so the only mods that I know that have been done are the air box cover & the exhaust has been uncorked. Thanks

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  • Matty05

Posted April 12, 2006 - 08:01 PM


You are running rich!!!! If it is breaking up, you are rich! If you are fouling plugs, you are rich!

Where is is breaking up? If in between closed - 1/4, it is the pilot circuit, if 1/4 - 3/4 it is the needle, if 3/4 to full open throttle, it is the main jet.

My guess is the weather has got hotter there if your bike ran good before!

What is your jetting specs?? My guess is you are way out.

  • moe396

Posted April 14, 2006 - 05:37 AM


I have not ridden the bike in hot weather yet, 40 to 60 degrees, mid 40s the last time I rode. Only occasionally when the throttle is 3/4 to full it will break up. I don't know what my jetting specs are I will look into that. I realize jetting is trial and error but does anyone have any suggestions. Thanks for the info.


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