timing question

[jonb45]

I was working on a friends 400 and he thinks that the timing chain got too loose and slipped on the bottom sprocket. Are there any marks on the chain so I can get it lined back up or does it even matter? And I wondering if there are any markings on a stock piston? Are there any numbers at all or does it just have those three letters on the top? thanks!!!

[guinness77]

There's quite a bit that goes into this.

Remove the round crank access cap and the flywheel round cap that's just above and forward of the crank cap. They are in the left side of the engine (If you're sitting in the quad).

Rotate the crank to TDC. You'll know it because if you look at the flywheel through that smaller hole you'll see the letter "T" stamped onto the flywheel. Don't confuse it with the letter "F". That means "FIRE". You want "T".

Remove the front plastic, gas tank, and heat shield.

Once that's dove you can remove the valve cover. That'll mean pulling the cross bolt from the frame that runs through the valve cover. Remove the breather line. MAKE SURE TO VERY CAREFULLY NOTE WHICH SPECIFIC BOLT GOES INTO WHICH SPECIFIC HOLE. I find that a drawing on a cardboard box works very well. Just stab the bolt through the like you drew on the box.

Once the valve cover is off you should see that the cam lobes are pointed DOWN. If they are, than you have problems elsewhere. If they're NOT, than it's time to replace the cam chain, upper cam sprocket, lower sprocket, chain slides, maybe the tensioner, and a bunch of other stuff.

Do yourself a favor. BUY A CLYMER MANUAL. $45 bucks now WILL save you THOUSANDS in labor casts over the long run.