Timing chain sprocket @ crank, gy6-50 By taterlove (Read 897 times)

[taterlove]

Is the timing chain sprocket welded-on/machined-in to the crank? I've been questioning th possibility that it's "spun" for a while now because I've gone through engine "A" top to bottom (haven't split the cases yet) and it still won't fire. I can take the stator, carb, head, etc., off of it and place it all on engine "B", set that next to scooter, hook up to the wiring and that engine runs...?

[Alleyoop]

I believe they are pressed on some even bolted on.

But before I would suspect the cam sprocket I would check the WOODRUFF key holding the FLYWHEEL in positon they are known to get damaged and allow the flywheel to rotate some on the crank. But easy enough to find out if the sprocket is turning put a mark on the sprocket and the shaft after you re-time it. You could also check the flywheel and the woodruf key and also put a mark on the crank and flywheel and see if the sprocket and or flywheel move off your marks.
Alleyoop

[taterlove]

Thanks!
I'd checked the woodruff key in times past and it was tight, but I looked at the keyway on the Flywheel tonight and, comparing it to the keyway on one used as an ashtray, it appears to be larger. I'll try swapping that out with a good one tomorrow and see if that's been the problem. If not, I'm going to put this fellow's components onto a good block I've got just so the owner can ride...
Also, from what I'm seeing in the image online for new timing sprockets, they are cogged, so there's little chance for that to have gotten out of sync.
Whatever the problem is, it sure has kept me stumped! I'll post what I discover. Again, thanks!

[grouchy]

This was one of the more interesting technical questions on regarding timing I have found on here, but alas; as is the case with many of the other threads...we do NOT know what his problem was, and there is no conclusion or outcome. Alleyoop's contribution is stellar as usual, but posters NEED to come back when they acquire the solution.