Modern Vespa

Rebuilding an LML - P200EFL clone engine. Everything is pretty much the same as P200 except that the primary gear is 66th tooth. I'm probably going to rebuild it with a standard 65 tooth gear but I am wondering if anyone has encountered that before? I can't find a 66 tooth gear listed on any Vespa engine specs, so maybe LML just used that to change the gear ratio? Which is better? Thoughts? Thanks

Yes. Working a set of cases for a customer and his primary is 66 or 68, cannot remember.

Well, what is your clutch? Figure out the ratio compared to 65/23. Understand if you are okay with it being under geared and do from there. I would bring it up to standard gearing. . .

What is the recommended final drive ratio?

What do you plan on using it for highway or around town or a bit of both? How fast do you want or need to go for a cruising speed? A purpose built motor for me to cruise at 60 mph looks different than an around town high rpm light to light racer. What work are you going to do to the motor while working on it? Such as a 60mm crankshaft? Pinasco or other 225 cylinder? Aftermarket exhaust?

Long range highway cruiser, capable of climbing hills. 210 Malossi topend, standard length crank, stock 24/24 carb, JL expansion chamber, short 36 4th, long 37 3rd

I have no experience with that engine combination, hopefully someone here does and can chime in. Do a search of the site , I know I've seen people with a Malossi upper end and expansion pipe. You've also changed 3rd and 4th gear so that's going to affect things also. As Gickspeed wrote you could start with the 65/23 and see what you think.

Well, my original question was why LML would choose to use 66/23 instead of the standard 65/23. I understand that there was only like 100 of these P200 clone engines made, so I wonder why that piece was different? Did they find that the gear ratio was better than 65/23?

Factory gearing setup is just a starting point, with what you have changed. I can tell you that from personal experience, I've put on a aftermarket cylinder to make a 177, and bought a Pinasco 225. I ended up changing gearing in both for my use. As Gick said earlier, pick something and go with it. My worry with the odd gear would be what is interchangeable with it? With my 225 I wanted to try a higher clutch cog or gear than the 23, I found a company called DRT that made a 24 tooth clutch cog specifically for that purpose. If it wasn't for that I would have had to change my primary to get where I wanted to be. My Pinasco 225 for instance is built closer to a factory setup with extra low end grunt that can pull the higher gear ratio. From my reading and understanding the setup you have will like to rev higher with an expansion pipe and a Malossi cylinder.

Out of curiosity I did a Google search and couldn't find a 66 tooth LML gear.