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07 YFZ450 wont start/bogging problem

804 Views 3 Replies 4 Participants Last post by  shaftman_05
About 2 weeks ago I bought a 2007 yfz450 that has been sitting for close to a year. when I got it I drained the gas and a friend of mine re-jetted my carb, cleaned it and added the "zip-tie mod". It has been running amazingly for about 2 days and then yesterday it started backfiring and it just quit when I was driving it around my neighborhood. I let it sit all night and figured it would be better this morning, but after riding it fairly hard for 5-10 minutes it just quit and wont start. I'm really new to this sort of stuff so any help would be appreciated.

PS..When I got it my water pump was leaking coolant so I replaced the outer seal and it seemed to fix it. I am not sure if this would have anything to do with it or not.
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Check your valves and shim them if necessary. May have something to do with it, and if not, it's an easy thing to do and it needs to be checked periodically.
Try Turing the motor over by hand when it's hot, could be the rod bearing going out.
Back firing is usually timing related. Check timing for being out of time and timing chain for too much slack. Does it rotate over after it stalls?
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