Timing Chain Worn?

I have just fitted a hotcams decompression cam into my '00 wr400.

The cam dots and crank dots lined up fine but when i released the tensioner the crank timing line moves a bit off, like 5mm.I tried moving the cams a tooth to see if that was better but it was WAY OUT then so i moved it back again,engine turns over fine but i havent started it yet.Could it be timing chain stretch? Its like a 1/4 of a crank tooth out(1 crank tooth =2 cam teeth)The bike has done about 3,000km and i always used full syn oil every 5,00km.What is the life of a timing chain? Are the chains known to stretch?...nervous.:applause:

I cannot answer your question about if your timing chain is stretched. But, they do stretch. When they do, the cam timing changes. Most engines end up with retarded cam timing when the chain stretches. This often moves the torque curve up in the RPM range a little bit.

Chris

Thanks mate,I think thats all it can be.So now to see how hard it to replace?:applause:

Sounds like the T chain is stretched. Probly never been replaced. If you can put in a camshaft you wont have any problem replacing the T chain. Do you have a manuel?

My '99 is on its 3rd timing chain (4th maybe?). They stretch and should be replaced as a part of regular annual/biannual maintenance.

I never thought they were that bad! Mate, its the original chain!

but it started ok and sounds good.Think i'll get me manual out and look into that one.:applause:

I had one catastrophic failure related to the timing chain back in '03, if my memory serves. I had just adjusted the valves and when I was reassembling, I thought "that chain looks a little loose". Not much, but a little. I figured it was ok. 500 miles later, the cam chain slipped a tooth on the intake cam and I bent a valve. The worst part was that I was on vacation in the north GA mountains and that ended the trip for me. Now, I replace the chain regularly. Total cost of replacement (if done carefully) is less than 50 bucks in parts and a couple of hours of your time. A new chain and a new left side cover gasket is all you need.

I had one catastrophic failure related to the timing chain back in '03, if my memory serves. I had just adjusted the valves and when I was reassembling, I thought "that chain looks a little loose". Not much, but a little. I figured it was ok. 500 miles later, the cam chain slipped a tooth on the intake cam and I bent a valve. The worst part was that I was on vacation in the north GA mountains and that ended the trip for me. Now, I replace the chain regularly. Total cost of replacement (if done carefully) is less than 50 bucks in parts and a couple of hours of your time. A new chain and a new left side cover gasket is all you need.

Rich - Can the cam chain be changed without undoing the head? Seemed to me there's not enough room and the chain is not quite flexible enough to bend around the crank shaft to remove (or install) from the top with only the valve cover and cams removed.

Rich - Can the cam chain be changed without undoing the head? Seemed to me there's not enough room and the chain is not quite flexible enough to bend around the crank shaft to remove (or install) from the top with only the valve cover and cams removed.

It can be done. I've done it more than once. It's tricky (actually, it's a pain in the ass) but it can be done. The chain isn't the issue, it's the chain guide (opposite the chain tensioner.) You have to unbolt the chain tensioner then work the guide loose to allow the chain to slip in and out of place. You don't really have to bend the chain. Just let it fall to the bottom of the motor and you can remove it. Put the new one on the same way in reverse. I use an extension magnet to grab the chain to pull it up to the top.

If you go the "easy" way, you have to drain the coolant and take off the head and cylinder. And the cost is higher because you would need new head and base gaskets in addition to the parts I mentioned above. Taking off the head is more straightforward but it is more work.

Nice one Rich,thanks for the tip.

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