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Old 04-23-2012, 12:43 PM   #9
simonpig OP
packin' heat
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Joined: Nov 2006
Location: NYC
Oddometer: 1,105
Interesting. I had a feeling it might be the hydraulic cam chain tensioner. The only thing is that upon inspection, you cant tell its working or not since it relies on oil pressure.

The cam sprockets look ok to me, and not worn at all. I was going to pull the rotor today and pull the chain to compare it to a new one to see. You mentioned measuring it while on the crank. How do you do that?

FYI, just want to note this the WR250R dual sport model and not the 250F racing yamaha's. Does this manual chain tensioner work on my bike?

Originally Posted by markk53 View Post
Your bike uses a HyVo chain. It should not wear out in 20,000 miles, they should last the lifetime of the engine. If it is worn out it would be the fault of a junk cam chain tensioner. I do know about those since I've been involved in making tensioners for Kawasakis and now Hondas for the past three years. Automatic tensioners mostly suck in design, especially the ratchet style. That is how I got into this, junk tensioners in two of my bikes.
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