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400ex problems

724 Views 2 Replies 2 Participants Last post by  SlammedRanger
I have a 2002 400ex I just replaced all the valves and put it all back together and I can't seem to get it to start. If I hold the throttle wide open with the choke on it pops every time the piston comes up. Any advice
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Sounds like its either timed wrong or the auto decompression plunger and spring arent in place. Did you adjust the valves after re-assembly? Could be tight or loose valves also.
When i time these engine i do as follows.
1. Put crank at T| on flywheel
2. Pull spark plug and check that piston at TDC
3. Put in cam with lobes facing down(check plunger+spring)
4. Line up cam gear lines to head surface with 3rd line up
5. Adjust chain until its tight in front all slack to back
6. Install tensioner and check lines are perfectly lined up
7. Install valve cover with metal gasket and adjust valves
8. Turn engine over by hand atleast 5 or 6 revolutions to make sure you dont end up with a valve sticking through the piston.
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