Trans sprocket clearance

[dustydog]

I’m working on a 79 xlh and the 23 tooth trans sprocket is hitting the sprocket cover stud just to the rear it. This is the 6 sided extension that the cover bolts to. The motor mount looks to be intact so why is this happening? Anyone seen this before? Thanks

[jim d]

I am not sure what tooth sprocket was on a factory stock fitment. Your 23 may just be a oversize one. It would think a 19 -21 was stock.

[dustydog]

I wonder what the difference in diameter is from a 21 to a 23.

[jim d]

I think that a 23 was about as big as you could go without clearance issues on the 74 XLCH that I had. But it was a 86 inch motor and could pull the bigger sprocket. Even then a sloppy chain could cause clearance rubbing under the kicker cover.

[chuckthebeatertruck]

23t almost always require grinding of the cover.

Here are a 19, 22, and 23t lined up. Bike was designed for 19-21t. There is a substantial size difference.

IMG_2248.jpg

[dustydog]

You’re not kidding. That is a huge difference. I think I know what happened now. The sprocket didn’t hit and wear into the 6 sided stud 34895-79. Someone ground it down to make clearance for the larger sprocket. That’s a relief. I was afraid I had a broken rear motor mount. That would be a bitch to replace. Thank you guys for your help. I appreciate it.