Posts: 5
Joined: 1/1/2017
Location: Merrillville, IN USA
I have rebuilt my 2010 crf250 with new head piston crank cam chain etc but it still doesn't run , has fuel spark . It will just pop out the exhaust like it's trying to run . I'm thinking the cam sprocket may have spun and messed up the cam timing ,does anyone have the cam specs ? I have access to a degree wheel and micrometer .
Posts: 3388
Joined: 4/3/2013
Location: Benton, LA USA
Edited Date/Time:
Are you 100% sure you are using the correct timing mark on the crank gear? With the marks lined up, is the piston at TDC? If not then the incorrect mark is being used.
Yes the cam gears can slip on the cam. Many post about this.
Sorry I don't have the spec's for the cam.
Paw Paw
Posts: 5
Joined: 1/1/2017
Location: Merrillville, IN USA
Posts: 384
Joined: 9/3/2015
Location: China Grove, NC USA
pull the plug and make sure the piston is tdc, and make sure the cam lobes are racing up on the intake side
Posts: 5
Joined: 1/1/2017
Location: Merrillville, IN USA
Posts: 3388
Joined: 4/3/2013
Location: Benton, LA USA
Edited Date/Time:
I would not do that. If the gear has slipped, then you may make contact with a valve to the piston and start another problem.
Did you check to see if the piston is at TDC with the marks lined up?
Paw Paw
Posts: 5
Joined: 1/1/2017
Location: Merrillville, IN USA
Posts: 172
Joined: 2/10/2012
Location: Elwell, MI USA
Put a dial indicator on your intake bucket and line up your tdc mark on your ignition during overlaop the intake should be around .082" with .005 lash if your cam has spun it will be a lot less lift i graphed almost every cam honda has made since 2003 and usally took a TDC lift number .
RHC
