Cam chain lifespan?

Hi folks,

How many miles is a cam chain normally good for? After having my intake cam jump a tooth and not finding any obvious cause, I'm leaning towards the idea of just replacing the cam chain and rear tensioner.

My bike has about 31K miles on it. I wouldn't have expected to need a cam chain that early, but maybe other factors might shorten its life? What have you guys seen?

Thanks,
Paul

 

I don't have any experience with the longevity of an XJ chain but I imagine the riding style and maintenance habits have more impact to it's lifespan vs. mileage. Does your bike have an automatic tensioner or manual? The manual 650 tensioner requires adjustment every 5k miles, I could see it skipping if you rode it hard and never adjusted it.

I can't find anything in the service manual about checking the cam chain, they do grow in length as they wear (some people say stretch but I don't believe that is the correct word). @chacal might have more info on the length of the chain and what is considered worn.

Again, no personal experience just thinking about it.

 

I think it is the links and pins that wear and that elongates the chain. My bike had 34,000 miles on it. The chain still had some life in it but l changed it as l had split the cases to replace the guide for the starter/alternator chain.

 

The 750s have the automatic tensioner.

 

Have you checked the tensioner spring?...not broken or damaged?

IIRC Early FJR's had an issue with the auto tensioner spring that Yamaha later revised.

 

if it's like a drive chain, the sprockets should be changed too, but then there's the crank.
what's the guide between the sprockets look like? mine had way less ware than the front and back guides.
here's a crazy one, could the valves have floated and knocked it off a tooth

 

another thought on that jumped tooth. while adjusting my mixture/idle if i get below 900 rpm the cam chain starts to rattle slightly, at 800 it's kind of bad and 700 is don't do this.
rolling down a off ramp with the clutch in the rider would never notice it...? i think most of these stall around +/- 800 but your fi might let it get to 700 or below