Upper Rev issue

[nightshifter]

Here is the background. I have a stock 05 400ex and have about 15hrs on rebuilt motor. 4hrs on since they did the 10hr breakin inspection/adjustments.

Yesterday I go to start it and one of the kids left the key on so dead battery. Try to charge wont take one. Want to go riding so I jump it with run of the mill battery jump pack. The reverse hook alarm came on the battery pack. Was hooked up correctly. Starts and idles fine. Even runs fine up to about 5000 rpm. Then it starts to dog down like when you have the choke on or hitting rev limiter. Even after riding for some time the battery wouldn't hold a charge to flicker a light.

I just went and got a new battery and it is charging. I dont have anywhere to test it by my house. Looking for ideas on what it might be for when I take it to where I can ride it. I am guessing that the new battery is not going to magically fix this issue.


Any ideas?

[NacsMXer]

It could very well be the battery, put the new one in and see if it helps.

That symptom you described can also be caused by a main jet that fell out in the float bowl of the carb. It will run fine up until about 3/4 to full throttle then will just fall flat on its face and dies out. Not saying that it happened, but is a possibility.

Try the battery, if it fixes it, great. If not, then you know the issue is not related.

[fmftrx300ex]

could ur stator be trash? not an experet just an idea, but if the light wolnt come on even when runing tht sounds reasonable