Modern Vespa

This is a follow up to a post I made last week. I'm unable to find that thread, so I'm posting here.

I recently bought a mazzy crank for a P200 rebuild. The clutch would not fit on the crank, so I called a friend at a reputable scooter shop where I bought it, and he said that was virtually impossible. I went back for another look, and thought maybe there was a small ridge near the keyway of the clutch.

Just for comparison I took the old crank, and the clutch fits on snug, but perfectly. The only way I would be able to get the clutch on the new Mazzy crank would be by using a drift.

I also noticed with the new crank, there is more resistance to moving freely in the main bearing.

I cleaned up the old crank and I'm sticking it back in the motor. It spins freer, and fits the clutch fine. Just for grins I'm going to take the new crank down to the place where I bought it and see how it fits with a new clutch there. I'm thinking it may be out of tolerances, or else I need a tune-up in the clutch knowledge department. Both are possibilities....

I can't stand it when I hear things like this from people. Anything is possible, and f****ing everything is virtually possible.

He said what was virtually impossible?

I just recently had a BGM crank come out of spec, but was easily fixed (only one out of the many I've had my hands on). BGMs build quality far surpasses Mazzucchelli, so its very possible that its out of spec due to manufacturing error.

He said it was impossible that the new crank was out of tolerance.

He's a good guy, and he was busy, but I suspect what he really meant was that it was highly unlikely.

I'll report back after I test it with one of their clutches.

Anyway, nice to button up my engine case today, finally.

How did you "fix" your out of tolerance crank?

I don't know how you would fix it or why you should fix it. I would return it and get my money back. Good Luck.

How I fixed it? Hot Rod Al machined the crank side taper (the clutch wouldn't fit on my crank either).

Why I fixed it? It was the last 60mm BGM crank available in the world til the next production run. In a perfect world, I would've returned it and got another one.

Virtually impossible my ass.

Another reason to own a micrometer.

Absolutely, I'm buying one...a digital one.

Travis, I was not replying to your comment, I was replying to Len's. If I stepped on your toes, I apologize. I just thought that it was kinda crazy to have to remachine a crank end that should be right in the first place. If it was returnable, it seems like that would be the better course of action .I just felt bad for Len, that's all. Again, apologizes.

I don't have any worries about being able to return the crank, this is a really stand up shop. I'd just like to see what the problem really is...if this crank is truly out of tolerance, might there not be others?

There was no malice in my post. Internet sucks for conveying mood, lol. "Virtually impossible my ass" was directed at the supposedly knowledgeable shop owner that Len referred to.

I was just stating why I didn't send mine in for a swap.

Figure of speech has to be input here.

Don't think anyone would really mean it.

It's kinda like when you tell your buddy you'll be there in sec........but what you really mean is after you're done waving at yourself in the mirror you'll be on your way.

Figure O speech.

It really just depends on what you are doing and what you want from your engine. Daily driver scooters that don't rev much over 6000 RPM can just have a boxed crank tossed into them without much worry. But engines that produce more than stock output and at higher RPM should have the crank trued/balanced before build. The additional cost will save money on both bearings, seals and future labor to replace those components down the road. Also, the benefits of less vibration is a real treat.

SFvsr, I can totally understand what you're saying. All those years ago when I was building Harley engines it was known that "Harley sells you the parts and you do the final engineering." I use to spend a fair amount of money getting those cranks trued and balanced - and it was worth it. Of course most harley engines will never see the rpm's that a Vespa engine will. Travis - We're cool.