Cam chain jumping a tooth

[Kuzzy]

Post a video of what it sounds like it.
Push kill switch down and then turn it over. Post that.

I'll get that Friday. You can tell if it is off by how it sounds? That is pretty interesting.

 

[Srxspec]

Anybody seen or have a cam jump time just by letting off throttle and hammering the throttle right away with a tune?

The cam chain would have to be extremely stretched or the tensioner fail for that to happen. The tensioner is oil pressure activated, so the likely hook of it jumping while running is pretty rare (unless you over revved the engine and had valve float, but even then rare).

 

[1nc 2000]

The cam chain would have to be extremely stretched or the tensioner fail for that to happen. The tensioner is oil pressure activated, so the likely hook of it jumping while running is pretty rare (unless you over revved the engine and had valve float, but even then rare).

I didnt think it was possible either.
Last night ran a grade for about 23 miles with about 5 road crossing in that stretch.
Ran between 85-100 mph most of the way at part throttle with temps about 10 below zero.
After that run the sled was having a rolling idle and would stall at idle also.
Only acted like this after exented running.

 

[Turboflash]

Anybody seen or have a cam jump time just by letting off throttle and hammering the throttle right away with a tune?

No

 

[KnappAttack]

Anybody seen or have a cam jump time just by letting off throttle and hammering the throttle right away with a tune?

Did it pop, fart, backfire or hit the rev limiter?

Typically those items can spit valve shims out, but you'd know it as it sounds like its running on two cylinders and you know something is wrong.

Doubtful the cam timing would skip if the engine is running however. It needs spun backwards, even just slightly if its not running can skip the exhaust cam if the tensioner is just ready to ratchet up to the next notch, otherwise oil pressure holds the tensioner tight if its running.

 

[1nc 2000]

Did it pop, fart, backfire or hit the rev limiter?

Typically those items can spit valve shims out, but you'd know it as it sounds like its running on two cylinders and you know something is wrong.

Doubtful the cam timing would skip if the engine is running however. It needs spun backwards, even just slightly if its not running can skip the exhaust cam if the tensioner is just ready to ratchet up to the next notch, otherwise oil pressure holds the tensioner tight if its running.

It did backfire when I chopped the throttle.
Sled sat in cold garage all night.
I fired it up and sounded fine cold.
Looks like time to pull valve cover and check valve lash.

 

[Big_Phil]

I didnt think it was possible either.
Last night ran a grade for about 23 miles with about 5 road crossing in that stretch.
Ran between 85-100 mph most of the way at part throttle with temps about 10 below zero.
After that run the sled was having a rolling idle and would stall at idle also.
Only acted like this after exented running.

Something may have froze from the snow dust and cold temps. No way you skipped a tooth from driving the sled. Even to spit a valve shim you have to over rev violently and even then it’s not likely. These sleds run 85-100mph effortlessly.

 

[KnappAttack]

Something may have froze from the snow dust and cold temps. No way you skipped a tooth from driving the sled. Even to spit a valve shim you have to over rev violently and even then it’s not likely. These sleds run 85-100mph effortlessly.

You can blow a belt and hit the limiter and spit a shim. It happens more than you know. Anti-Lag can spit shims. Backfires can spit shims if they open and float the valves.

 

[Big_Phil]

You can blow a belt and hit the limiter and spit a shim. It happens more than you know. Anti-Lag can spit shims. Backfires can spit shims if they open and float the valves.

It can happen, but it’s rare. I have anti lag. Use it every ride, mostly for power wheelies in snow and the light show at night. Blown belts at full throttle. Broke a clutch weight at full throttle at 120mph once too. Might be I’m just lucky

 

[stgdz]

I'll get that Friday. You can tell if it is off by how it sounds? That is pretty interesting.

 

[Kuzzy]

You can blow a belt and hit the limiter and spit a shim. It happens more than you know. Anti-Lag can spit shims. Backfires can spit shims if they open and float the valves.

Interesting, I see that td has an anti shim spitting kit with springs. Might have to crack open the engine in the off season. Hopefully when I pull the cover I don't see anything in there that cuts my season short. At least I still have the king cat to drive, but with a 162x3 track, I wouldnt be doing much trail riding lol.

 

[KnappAttack]

Interesting, I see that td has an anti shim spitting kit with springs. Might have to crack open the engine in the off season. Hopefully when I pull the cover I don't see anything in there that cuts my season short. At least I still have the king cat to drive, but with a 162x3 track, I wouldnt be doing much trail riding lol.

Have a buddy that has the Kibblewhite kit and springs and it still spit 3 shims out when it backfired.It may be better, but its not foolproof either.

 

[1nc 2000]

10,200 miles on sled.
Tuned since 2500 or so miles.
Cam timing is right on for both cams.

All exhaust valve clearance check would take a .009" feeler gauge and .010" would not go in.
So all exhaust valves clearances are within spec.

All intake valve clearance check would take .007" feeler gauge but .008" except for one was at .006".

All checks good so going back together.

 

[Kuzzy]

Have a buddy that has the Kibblewhite kit and springs and it still spit 3 shims out when it backfired.It may be better, but its not foolproof either.

View attachment 166352

I can't find the kibble kit. How does it compare to the td kit? Nothing is ever foolproof for sure. By the size of that little shim, I'll have to be on my toes looking for something so small.

 

[1nc 2000]

I am happy that I checked mine and everything looks good. Now I know where its at for valve lash and know I won't need to check it for at least another 10,000 miles.