bike missing at 50% and above ,throttle-help

I raced a Hare scramble today and my bike would cut-out while sitting on the stand whenever I applied full throttle.I drained all of the gas in the tank and carb and put in 50/50 race gas and a new plug.checked the mainjet (172) and it was clear.the bike continued to cutout.

Well I couldn't do anything else before my race started, so I went to the line.Bike started first time several times,but when the flag dropped and it really counted, it took about 10 kicks.But during the race down staights at full throttle,it was running fine under a load.I ran a decent race, but when I pulled in and revved the bike up, it would still miss.

Any suggestions on this?I had a clean filter w/o too much oil and a new plug.I have been racing this bike for 2.5 yrs and have never had this happen.I'm thinking it may be the ignition cutting out. Is there any way to check this?


Jeff #414

Could someone please give me some suggestions on this one?I took the carb off today but haven't tore it down yet.But all of the octapus hoses were all intact.Plug was dark, but not saturated.Hot valve seemed to be sealing properly.Surely somebody else has experienced this.



Once I had similar symptoms on a XR600 and it turned out that I had by mistake adjusted the valves WAY tight, wich caused the bike to miss.

This is probably not the problem with your bike but if you can't find anything else then maybe you should check your valves.


European 2000 WR400

neutral position switch in conjunction w/ (neutral position) rev limiter cut-out...???


'99 WZ with all YZ mods, FMF PowerBomb header, Stroker SX-1 silencer, SS front brake line, forked over by Pro-Action, OEM YZ tank and IMS seat.

The bike will do this when the clutch is pulled in and in gear.Also, the head had a complete valve job about 5 months ago.I tore the carb down tonite and found nothing unusual.Will try and fire it up tomorrow and see what happens.



-Was the accelerator pump squirting strong?

-Have you made any changes to jetting?

-There is a procedure in the manual to check the TPS resistance, be sure to do a check on it.


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