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adam080145

Problems after cam change

7 posts in this topic

hey everyone

Been having some issues, decided to do a oil change, and cam chain change on my bike and while I was at it swap the war cam for a yz450 exhausT cam.

Anyway all back together everything seemed to line up ok with tdc marks, also found with spark plug in it was really easy to turn bike over which doesn't seem good.

Problems I'm having is if I start the bike and pull the choke the bike struggles and I took the bike for a spin and the bike cut out mid acceleration and on restart it back fired and the starter motor struggled to turn the bike over if at all.

Any ideas, some pics are below any help would be great.

Edited by adam080145

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Been having some issues, decided to do a oil change, and cam chain change on my bike and while I was at it swap the war cam for a yz450 exhausT cam.

You need to trim the decomp pin to act identical to the WR decomp pin, or e-starting is a thing of the past.

See http://www.thumpertalk.com/topic/1141940-wr450f12-how-to-grind-a-yz-cam-for-e-startability/

 

But that backfiring and cutting out mid acceleration is something different, definitely not cam swap related.

A WR with a correctly timed YZ ex. cam runs great, only want to be kick started.

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Using the correct timing mark on the crank, the two timing dots on the cams should be lined up with the deck of the cylinder top, cam lobes facing away from each other.

 

Follow the timing instructions in the Service Manual.

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Yea I followed the manual and stuff on here. The exhaust cam punch marks were dead on the inlet were a Mil below but a tooth in either direction would make it worse.

It started first time. Idled fine reeves fine. Just when I took it for a blast accelerated and it cut out like I hit the kill switch then just back fired if I tried to restart it.

I'm checking the clearances later. I'll post up my findings.

The cam lobes do face away the exhaust is just a tad higher but again a tooth in either direction would make it worse.

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