Front sprocket for 160 Monza Jr

[DesmoDog]

In my push to make progress on my 160 I'm starting to think I may need to enact "Plan B" on the front sprocket.

I realize that the sprocket from a larger narrowcase will fit the countershaft, but the chain won't the sprocket as the 250 used a 428 chain and the 160 used a 420. The difference is in the width, which gives me an option. I can either find the correct sprocket (I've been looking, no luck so far) or get one for a 250 and have it machined down so the narrower chain will fit (the aforementioned Plan B).

So... what I'm looking for is either:

1) a source for a 16 tooth, 420 chain sprocket. I've been looking for a while, no one seems to have them. I'd even settle for a 15 tooth.

or

2) a source for machining a common, thicker (428?) sprocket down to the 420 size - and then re-hardening it?

Speaking of hardening, I tried to cut the teeth off a c/s sprocket years ago on my lathe and the sprocket shrugged off my attempts. I think I scratched it a little but that was about it... Needed carbide tooling? HIgher speed? I dunno, I gave up pretty quickly.

[DewCatTea-Bob]

" I can either find the correct sprocket (I've been looking, no luck so far) or get one for a 250 and have it machined down so the narrower chain will fit
So... what I'm looking for is
a source for machining a common, thicker (428?) sprocket down to the 420 size - "

____ I've done this at least once, (also a 530-12t down, to use #520-chain).
Ya have to use a grinding-wheel (& time!). _ The first time, I used only a rotory-sander.
Either way, the grinding-work takes more time than ya might think. - Ya have to keep dunking the sprocket into water, to keep it from getting too hot!
__ I happen to know that there's a Honda-sprocket that fits for this use, as I know I have one -(a 14t, I think)!
While the Honda-sprocket is not an exact/perfect fit, it's close enough to do the job! _ It just requires a spacer -(which I have made by lathing-down pieces of 1/2" water-pipe).
Right now, I can't recall the exact Honda-model but, it was definately from either a late '60s or early '70s, 90/100/125 single. - (I'm thinking a 125SL.)
Whatever, I think I still have a few NOS examples, maybe some 16t as well,, don't recall for sure - (they're not currently where I can get my hands on any of them now).


Hopeful-Cheers,
-Bob