[Monzatastic]

Martin, sweetheart that he is, traded me some stuff and I now have a 1 speed Avanti engine. I ripped into it tonight to get the crank out and made an interesting discovery. The 1 speed Avantis have a different internal ratio than either of the 1 speed Garelli engines. Holy Crap. Vertical engine standard for internal gear box reduction on a Garelli is 14 x 39. The Avanti counts 20 x 33. Not only that, but the main and output shafts are totally different. Garelli used a tapered press-fit driven gear for their 1 speed while Avanti went with a shimmed and modified version of the 2 speed shaft to fit their keyed and friction-fit gear. My mind is blown. This is the first cool thing Avanti has ever done. Pics, because it happened:

Garelli Monza on the left, Avanti 1 speed to the right.

And now, for the setback. You were expecting that, right? Of course you were; you’ve been reading my blog after all. As I was pulling my Monza cases apart, to prep for the new crank install, the bearing that I peened into place removed itself. I’m going to fucking start over and cut another case. I don’t feel comfortable with this case. I plan to go fast on this build, I don’t need bearings spinning.

Lastly, just to gloat, as a single dude living alone, I can do this to my kitchen floor. (I can also put engine parts in my dishwasher. Being a bachelor rules.)

I probably should have known about this. ugh. Turns out the throw on a Monza crank is 5mm longer than a VIP. Here’s a pic to prove it:

The piston protrudes past the top ring. Here is a pic of the jug adjusted to bottom correctly in reference to the exhaust port.

It’s kinda hard to tell in the pic, but 5mm is the deal. The good news is that the Monza is still a 39mm stroke, even though the con rod is longer. This is accomplished by making the Monza jug taller at the base. I need to fab a base plate to take up the slack. Port timing should not be affected. Here is a comparison shot:

From left to right; 50cc 3 speed jug, 50cc Avanti, 50cc Monza.

Note the difference in base offset. Lastly, we have a pic of the engine mocked with head on. Ooolala.

I’ve got the cases back together and I’m stoked. Pic update!

I cut gaskets today, aren’t they pretty?

The engine isn’t ready to go back together yet, still waiting on a few parts. I also need to bore out the case to accept the large diameter of the meceur kit. I can’t really roll on anything else until I get this bad boy back together, so I’d best get on it.

Also, I don’t know about you, but I always hated making bolt holes through gaskets. It was the number one way I’d fuck up the piece I had just spent half an hour cutting. Not anymore! I bought this hollow punch set at Bargin Supply and am in love. You pick the appropriate size punch, line it up, and smack it with a hammer. Instant perfect hole. Amazing!

Bad Monza news today folks. I pulled the engine to tear it down so I can begin the rebuild process. Apparently the farmer I bought it from fancies himself a mechanic. F U C K. When I picked it up, he was trying to start it in the yard, and thankfully, it had stopped sparking. If he had gotten the thing to fire it would have eaten itself on the spot. He told me he had ‘rebuilt’ the c lutch which, as far as I can tell, meant he took it apart and then put it back together minus a few parts and no more than finger tight. So, here we go.

The stock topend is pretty epic, I had never seen the inside of one before. The transfer ports are wider and slightly taller than a VIP, while the intake is wider but more squat. There is also a boost port with a cut out in the piston. The piston has thiner than usual rings, and the top one is a dyke. The topend is unfortunately ruined, looks like a ring shattered and gouged it pretty deep by both transfer windows.

The head is also really cool. Super big fins for maximum cooling, as well as a really aggressive squish zone. It takes long shank spark plugs.

This one was my bad. In the process of pulling the driven gear off the shaft, I applied a little bit to much force, and it shattered. The bad news: it is not the same as a 1 speed NOI, which has a primary reduction of 16/71, while the Monza has a primary of 18/67. The maybe good news: I called Nick’s Moped in Coldwater, Oh, and he may have a gear for me! Just to hedge my bets, anybody care to count the teeth on their parts Avanti one speed??

When I split the case I found mud. Like a lot of it. I have no idea how it got in there. It would seem that Farmer Mechanic failed to replace the two rear case bolts when he put the cases back together. He also failed to reinstall the bearing face spacer on the main shaft. He also may have damaged the mag side bearing seat, as the bearing that is in there slides in and out a good half inch. There is red RTV all over the place. Bearing and seal set looks to be the same as a regular 2 speed VIP.

This is the crank as I pulled it out. Note the small piece of ring jammed in the big end bearing lube slot, as well as the seal spring stuck on the trans side. The crank is fine, I don’t this dude ever got it to run in it’s current condition. I think dude smashed a ring, split the cases trying to “fix” it, and then couldn’t figure out why it didn’t run. So he sold it. This is going to be a lot of work.

I have been after a set of Garelli NOI Matic circle mags since 2005 when I first saw them in a picture on mopedarmy. I finally got one; as in just one. I am the proud owner of one rear Garelli circle mag. NOS courtesy of Chad over at Quarter Kick Check this shit! Hottest mag wheel ever.

The Monza build is slowly coming around, lack of funding non-withstanding. The cylinder will be a Mec Eur knock off of a vintage 49mm Zeta; huge ports, poor machining, chintzy material, but hey, doesn’t need to run forever. 49mm bore yields a 73.5cc displacement. I had one of the vintage Zeta’s for a while and it ripped right up until it smeared piston everywhere.

The clutch on a Monza GT is the same as an NOI, so I’ll be using this sweet Mercadosur made 80.80 shoed clutch straight out of South America! Not sure what the 80.80 stands for, but it’s an aftermarket replacement for the rubber clutch from a kickstart NOI. This of course means that my starter clutch will no longer work. Goodbye clutch lever, hello pull start! Both the kit and clutch came from Ed (mopagen); he has epic Garelli stuff. It seems to mostly be from South America where, apparently, Garelli’s are still a big deal.

Obviously I’m still a ways off. I’ve got a 21 phbg that should do the trick, but I haven’t yet figured out a pipe. Nor does the damn thing run yet. Winter is the operative word here. Blast in the spring.