2004 YZ450F weird cold start

2 replies to this topic
  • diesel_dean1

Posted March 06, 2016 - 01:56 PM


Okay. So I have a 2004 YZ450F and its very weird with starting. Oil is immaculate as well as filter and air filter. I run 96 octane pump 93 mixed with 100LL avgas. And for some reason my bike likes to start with the hotstart when its cold. When its hot. It doesnt even need it. And sometimes to start it needs choke and sometimes it doesnt its weird. Its kept in a heated garage. Im not sure whats up but it has insane response. Its got plenty of power. And I got this not too long ago after moving off of a two stroke. I just didnt want to deal with pistons and what not. And I wanted to try out a fourstroke. So could I be flooding it? I've ridden my buddies yz400f and you have to snap the throttle to spit some fuel into the motor. and iM not surenif its the same

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  • diesel_dean1

Posted March 06, 2016 - 08:16 PM



  • grayracer513

Posted March 06, 2016 - 08:32 PM


Part of the problem could be fuel related.  Home brewed fuel based on AVgas will sometimes exhibit hard starting when cold, especially in the colder months of the year.  Whether the mix actually ends up being 96 octane, pump 93 is more than the stock bike needs.  The behavior you're describing sounds like an overall lean condition.  


You might try switching out the fuel with straight pump premium to see what effect that has on starting.  

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