2011 crf450r need help

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4/1/2018 10:36 PM
Edited Date/Time: 4/1/2018 10:40 PM

Hey guys I have a head scratcher my brother has a 2011 crf450r just rebuilt new piston rings valves put it together tried to start it nothing so check timing and valves they both was spot on kicked more nothing still it did how ever bump start and ran flawlessly like a freshly rebuilt engine should shut it off and still it would not kick over. Took the head off again nothing changed valves are in spec and timing is dead on what else could it be? We are out of ideas and hoping some one on here may have the answer thanks


4/2/2018 1:11 AM

Did you have the valve seats re cut before you put new valves in or did you put new valves in the old seats? You cant mix old seats with new valves or they wont seal and youll have hard starting.


4/2/2018 6:26 AM

Seats are fresh


4/2/2018 6:51 AM

Hmm idk.

My next step would be a leak down test. Possibly look into a leaky injector or if youre touching the throttle while kicking. Could be flooding it. Bump starting would give the bike a chance to clear out the excess gas.. just a guess.


4/2/2018 11:56 AM

Update I went and actually kicked on it and It a lot harder to kick than my kx 450f and actually will come to a very stiff part that you can't kick threw you lift up a click on the kicker and you can kick again could the auto decompression be causing this


4/2/2018 2:27 PM

OH youre having a problem physically kicking it. Shit my bad lmao. Yea sounds like youre hitting the compression stroke. Take a look at that auto decomp.


4/2/2018 6:52 PM

You may be using an incorrect timing mark on crank or stator. There are a couple. If on an incorrect one you will have your problems listed as the relationship of the cam timing will be incorrect as it relates to the piston position. Double check your piston position when you install the cam on their marks.

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