Cam Chain Tensioner

Fellow TT'ers. I'm going to share my mistake for all to learn from. I value all the great info on TT and appreciate lessons learned from others so now it's my turn to share my embarassment (I mean my lesson!).

When it comes time to remove the cam to adjust valves, per the manual, you must install a small screwdriver into the cam chain tensioner and rotate clockwise to remove the tension off the cam chain then hold the screwdriver there because it is spring loaded (Antman's zip tie to the frame works great). When you've completed your shim work and it's time to allow the cam chain tensioner to resume its job, simply pull the screwdriver out, allowing the spring to recoil the tensioner back to the "tight" position. This is how it's supposed to happen.

Here's where my learning comes in....When you first start to remove the tension only turn it clockwise a turn or two, just enough to remove the tension, you'll be able to see the chain go slack off the cam sprocket. DO NOT TURN PAST THE RESISTANCE YOU'LL FEEL after about two turns. Furthermore, don't reach in with your screwdriver after you've released it and turn it counter-clockwise to 'verify' that its all the way in! I believe this was my downfall as it deformed the spring enough to slightly jam it which led to it comming loose and the chain jumping a few teeth which, of course, led to Mr. Intakes playing patty-cake with Mr. Piston. What's worse is it happened at one of the many times I was in the process of kicking PatD's ass! Result: bent valves ($65 ea.), ruided cam chain tensioner ($50), and, most importantly, a painful DNF loss to PatD (priceless!).

Don't be intimiated by this simple procedure! Just don't go beyond the mechanism's limits as I did. It's just a recoil spring (like a lawnmower's pull starter) and is easily tweeked. I took mine all apart to study it and it's quite difficult to assemble back together correctly once the spring is deformed. This must be the reason you can't just order a $2 spring, you have to get the assembly ($50).

Hope someone can take advantage of this!!!! :)

For $5 you can buy the tool that the manual suggests you build.With this tool, I doubt you can damage the spring. I bought one and it works great.Amazingly small, but effective. You can see the ad for the tool in

I took my tensioner completely out with the two 8mm bolts that hold it in. Then, with the tensioner in my hand screwed the srping back and held it place with the tool or screwdriver then bolted it back up. No problem whatsoever!

yeah... i couldnt find in the manual anywhere explaining how to setup the tensioner. i've been running it a little tighter then how it sits naturally. I'll reset it to its now i've read this :worthy: (reset = turn anticlockwise and release until it rests with its own tension) - this is correct, yes?

there is no set-up to an auto tensioner.......get a manual's have failed on 02-03 bikes.......btw this thread is 5 years luck mate

is resetting the stock tensioner as easy as turning the bolt in the middle clockwise until it stops and then releasing it? do i have to be at TDC?

is resetting the stock tensioner as easy as turning the bolt in the middle clockwise until it stops and then releasing it? do i have to be at TDC?

it has to be rewound and then mounted.......then let go of the flatblade.......tdc? no

it has to be rewound and then mounted.......then let go of the flatblade.......tdc? no

I have to take the thing off?

I have to take the thing off?

no get a tool..........go to ebay and type in crf450 cam chain tensioner....10 bucks......02-03 tensioners are the same.........04 on up are different

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