04 450 Chain Tentioner

I did a valve check on my nephews 04 450 over the weekend. This was the first valve check this bike has had since NEW. Ouch... Luckily they were all on the tighter end of in spec but I let them go until next time (much sooner...).

The oddity was that I noticed at TDC Compression the cam chain seemed excessively tight. I pulled the cam chain tensioner off to make sure it was working right and it seemed to be stuck. I had to give it a really good turn to free it up. Wound it down and installed it again, gave it a few kicks to spin it around and then the chain had a little give at TDC compression.

Will these chains tighten up like that or is it normal on these motors for the chain to be tight at TDC compression? As long as I got the tensioner in and its working right it should be fine correct?

First, let me point out that the valves are always set at the tight edge of specs at the factory to begin with. No worries. In spec is in spec.

On the chain tensioner, it will take up any slack it ever finds and will not let it back off. The chain will most likely be as tight as you first found it after the next time you run it up to 10k again. As long as it operates smoothly, and cannot be forced to compress without turning the screw, it's OK. They can develop a stuck feel when trying to unload it in place, but that's also fairly normal. Loosening the mounting screws will relieve the pressure on the plunger, and make it easier to unload. You can also just remove it and unload it "on the bench". It's usually easier that way.

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