250x keeps jumping timing

[Joshwfl]

1987 250x runs great then dies. Every time, the timing is off. I reset it, but when turning the motor over after one full revolution the timing gear will be off 2 teeth, then 4 after the next rotation and so on. The cam chain is tight, but I can move the cam gear and chain without turning the crankshaft. If I turn the crankshaft the cam spins but does not keep correct time. What happened?

[300exOH]

Sounds like you need a new timing chain and/or tensioner

[Joshwfl]

Just replaced the tensioner today, the chain is super tight.

[300exOH]

Originally posted by Joshwfl
Just replaced the tensioner today, the chain is super tight.

Have you checked for any damaged/missing teeth on the gears?

[300exOH]

Also even if the tensioner is new the timing chain could be stretched causing it to jump time.

[Joshwfl]

Just took the cylinder off, when the tensioner broke last night it allowed the chain to come off the bottom gear. Both gears are good, put it back together and reset it, runs good now.

[300exOH]

Originally posted by Joshwfl
Just took the cylinder off, when the tensioner broke last night it allowed the chain to come off the bottom gear. Both gears are good, put it back together and reset it, runs good now.

At least it was something simple. Good to hear you figured it out.