[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.