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jdarroyo

2002 YZ250F Cam Chain????

12 posts in this topic

I justed pick up a used 2002 YZ250F and wondering if i need to replace the cam chain on it???? How do you know when to replace it???

Jason

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Do you know when it was done last?

If not, just do it. $20 worth of the cheapest insurance you'll ever buy.

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If you don't know when it was done last, just do it. These chains stretch like crazy due to the automagic chain tensioner (stretcher). It's cheap insurance.

Take off the little bolt covering up the screw in the adjuster and turn it until it bottoms out, and count the turns. A new cam chain and good cam chain guides (not worn out) will give you about 1 1/2 turn until it bottoms out. If there is more than 1 3/4 to 2 turns, then that chain is gone (of course in my not so humble opinion).

Of course you need the special tool to remove the ignition rotor to do this job.... And a new ignition cover gasket wouldn't hurt either.

And don't forget to check the valves while you're at it. If it's a 2002, they probably need to be done too...

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If you don't know when it was done last, just do it.
Gee, that sounds familiar. :thumbsup:

But, I'm glad you agree.

These chains stretch like crazy due to the automagic chain tensioner (stretcher).
The life of the chain is extended by the presence of the automatic tensioner, not shortened. What stretches them is driving the cams. The pressure applied to the back side by the tensioner pales by comparison to the load on the front side at 10,000 RPM. You keep it from driving the camshafts, and they will last forever.

The thing you can't tell by the method of counting turns on the tensioner is whether the chain has any tightened links (kinked). The actual number of turns the tensioner will take on a new chain is going to vary significantly from bike to bike, as well, but the method works if you remember to make a note of the turns taken up when you put your new one in. And on the subject of special tools, don't forget the #27 Torx for the stator plate.

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ya change it, everytime i check my valves i pull the head and just change the chain, I dont know if this is true or not but somebody said that regularly changing your cam chain will help with wear on the crankshaft sprocket thats at the bottom, because it cant be replaced without buying a whole new crankshaft. Like i said i don't know if this is true, anybody know?

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ya change it, everytime i check my valves i pull the head and just change the chain, I dont know if this is true or not but somebody said that regularly changing your cam chain will help with wear on the crankshaft sprocket thats at the bottom, because it cant be replaced without buying a whole new crankshaft. Like i said i don't know if this is true, anybody know?

yes it's true. the sprocket on the crank is part of the crankshaft. A stretched chain greatly accelerates the wear on the crank's sprocket.

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Yamaha kid save yourself some time it's not needed to pull the head to swap cam chains just a tip to save a headache next time.

i pull the head to clean the carbon off the head, and make sure the valves are sealing

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