WR400 dies at idle or while riding?

2 replies to this topic
  • USR54

Posted June 01, 2011 - 02:59 PM


Please help!!! My WR400 will run just fine for a few minutes after warmup then will just die instantly. The problem started slowly, then got progressively more frequent. It will die at idle or while riding at speed. Before it dies it seems to be running normally. I have recently soaked, cleaned and blown out the carb internals without making any adjustments. The jets are clear and I have noticed that in addition to dieing on it's own, it also will die when easy throttle is applied. I have not changed the plug recently but feel that can't be the problem because it runs to good before it quits. In my mind, it sounds like electrical or carburation but I don't know where to start. Does anyone have any ideas for me. Thanks for your time and input.

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  • William1

Posted June 02, 2011 - 02:58 AM


Try the spark plug first. Then do tests on the stator.

  • miweber929

Posted June 02, 2011 - 03:01 AM


Replace your pilot jet with a brand new one and your plug before digging into a whole lot more. I'd also suggest raising your idle slightly too, there is a spec (like 1500?) but without a tach I just make sure the bike idles nice and smooth without an overly high rev.

Also, its likely your carb may simply be getting worn and leaking air as they were not all that great to begin with and it's now well over 10 years old. Lots of threads for checking for air leaks, do a search. If it is worn, upgrade to a newer style WR or YZ carb. Again, search if that is the route you decide to go.



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