Yfzr starting issue

[quadrdr77]

I have a 2010 Yfzr that is a complete pain in the *** to start here lately. It has potted polished head cams over size valves etc etc. My problem is when you first try to start it when the engine is cold it clicks like the battery is dead or is just slow turning over and won't start. Put a battery charger on it and it starts right up. Does the same thing when I go out and run a moto of mx come back shut it off and then try again, nothing. I've put four batteries on this thin and I'm starting to get a case of the *** with it. Any help or suggestions is greatly appreciated.

[Holy Kaw!]

I know on the KFX450's they have the same problem of the batteries dying fast and it has been proven to be the ECU. Once you replace the ECU with a Pro Com ecu on the kfx the battery problems are completely gone.

Might be the same problem if they both use the same brand ECU.

[joep1219]

i don't know anything about yam, but it sounds like a de-comp may not be working all the time.

[Vampire2800]

I have a 2010 yfzr & I had a very similar problem for a few months. Turned out to be the brushes in the fuel pump. You're describing the exact same problem I had, though. My local dealer covered it under a 30 month emissions warranty that all new YFZR's come with. I had no idea there was an extra warranty like that. Good luck.