2010 YZ 450 hard to start.

6 replies to this topic
  • brj120978

Posted July 16, 2012 - 05:30 AM


I have a 2010 Yz 450 that is somewhat hard to start. It takes about 5-10 kicks when it is cold and close to 20 when it is warm. When it first starts up when cold it tends to die if I do not rev it. Once the bike is running, it runs great. I am not very mechanically knowledgable so I was curious what may be causing this. I was going to take it in to have the valves adjusted but I wanted to see if there may be something else causing this. I didn't want to take it in to have the valves adjusted then have to take it back if it is something else when they maybe could fix it all at once. Any input would be appreciated!

  • merk57

Posted July 17, 2012 - 11:15 AM


get your valves adjusted.

  • jk322

Posted July 17, 2012 - 12:20 PM


I am not as savvy with FI as some others here, but it sounds like valves to me too.

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  • rcmxracing

Posted July 18, 2012 - 11:28 AM


How many hours on the bike? If you don't have an hour meter or your own Yami tuner you can borrow a tuner to get the total hours. Probably a dumb question, but since you didn't mention it...here it goes: You know about the cold start button/knob, right? It's also an idle setting, turning it out increases idle. I have the 2010 and for starters, don't waste your first few kicks expecting it to start when it's been sitting, i.e. cold. You've got to charge the capacitor, so I do a couple easy "kicks" to do that, then I give it a solid kick. After I tore my ACL I didn't have the leg strength to spin the engine fast enough to start...so would use my left leg, or get a buddy to start it. I will say it is a little finicky to start. I also hold just a "crack" of throttle when kicking - either cold or hot, barely any, but it helps. Watch out cuz you can flood it just like a carb bike. When it's hot if it hasn't started after 3 or 4 kicks I actually pull the cold start knob...and it starts! Best advice is a solid kick and a crack of throttle. I think there's a thread about this on TT somewhere.

  • brj120978

Posted July 19, 2012 - 12:21 PM


About 120 hours on the bike total. About 20 on new top end. I bought off a friend so I am not sure how it is supposed to start. This may be perfectly normal. I came off a 250f and it started first or second kick everytime. It is just frustrating when I stall it in a corner or something and it takes forever to start. I just dread taking it to a shop and paying them $150 for valve adjustment and that isnt even the problem.

  • merk57

Posted July 21, 2012 - 02:10 AM


be weary of cracking the throttle when starting it, I've done this a couple times and my knee diddnt enjoy it. the bike will kick back on you HARD.

  • Iminyaface

Posted July 23, 2012 - 03:15 AM


I'd say it would be a valve issue, my mate got his 2010 Yz450 rebuilt 3 months ago and it was doing the same thing hard to start and kicking back on him about 10 hours after the rebuild,
would start first or second kick every time before the rebuild.
He took it back to the shop and the valves we're out of whack.

If it we're mine i would be taking it in right away because if something happens to go wrong it's gonna cost you alot more than just getting a service.
Once it's running top notch you'll be kicking yourself for not doing it sooner :)

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