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08 Honda 420 timing issue?

3426 Views 9 Replies 5 Participants Last post by  shadetree, 
Carolynskii
I rebuilt this bike from mud junk that didn’t run. Now it will start but blows out the throttle body. Valves are adjusted tdc on compression stoke ok and cam is set correctly under front cover with a new timing chain.
Is it safe to say the cam is bad?
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Carolynskii
Hmmm maybe it’s sticking. I replaced the valve stem guides tho and valves were straight. I know it’s not tight because it wiggles at tdc.
I have seen the cam face in mud bikes spin out of time before. I thought maybe this cam had the timing out a little.
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Carolynskii
2
Retro you know darn well I don’t have any fancy measuring tools like that! Lmao
I did pull the head and did a backyard test by pouring gas over the valves to see if it leaked through and the compression valve poured gas thru it so I gotta lap that one.
I also noticed I had two marks on top my brand new piston which indicates that it’s definately out of timing so I’m gonna put another cam that I have laying around on it and see it that cures it.

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Carolynskii
Cam wasn’t very worn but the face with the theeth were off. I replaced the cam readjusted valves because the new cam made em really tight and I lapped that valve. She purrs like a kitten now sounds quiet like a new one.
Thanks for the help y’all I got lucky on this one.
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