Modern Vespa

P125X
ROAD2 exhaust
Malossi 177 kit
Autolube
Fast flow tap
Drilled carb/filter
26/26 carb

52/150
120/be4/118


Fastest I can get it is 62.9, tucked down, on a 1/4-1/2 stretch of road.

Only port matching was the carb box to the engine.

Is this a realistic max speed as-is? Or am i missing some easy mods?

That's it till you mess with gearing.

Good to hear. I know theres stuff with the intake/exhaust ports, cutting the crank, cutting the piston, etc. but im pretty happy where im at.

Managed to squeak out 64.2 w/ a 122mj just now. Probably the best im gonna get though.

I assume you mean a 122 main jet?

Do you have a *need* for more than 62 MPH, or do you just want it?

Because everything you do from where you're at now is going to increase the odds that you blow up your top end.

Build a motor that matches your riding needs and it will be more reliable, meaning you'll be happier as a result. Chasing speed and power for no reason is just spending money to create the need to spend more money.

Need? No. Just want to make sure im getting everything out of my current setup. I rarely go over 35, but if the ability to maintain 60+ for a few miles is there, id like to know it.

I'd wager that if that you got 1.5 additional MPH at WOT by upjetting from 118 to 122 (if I got those numbers right), the 118 was too lean. Unless wind and the road grade and temperature and any other factors changed between the two measurements.

This has pretty much been my plug color since i put the kit on. The main started around 125/128 and the plug was black, worked it down a few steps, and sitting at 120 right now.

If that's 120, go back to the 122.

What is your current gearing? Over 60 mph is quite decent if the engine is running cool and you are able to sustain higher speeds without overheating etc. I get that you want to know you are getting the most out of your engine, but it makes much more sense to set it up for the speeds you normally ride.

I'd assume it's stock gearing.

Of course, extending the gearing is going to make it feel slower in the speed range you usually ride. It also assumes that your power curve is wide enough, too. Otherwise, it'll have gaps and flat spots and be less satisfying to ride.

Stock gearing as far as i know. Been messing with the main for a while now. Looking at picking up a CHT gauge to get an idea of temps. I rarely go wot, but thats because i rarely drive roads that are suitable for it.

Thats with the 118. Malossi sent a 116(i think), Ive run everything from 118-128.

Your gearing is probably a 21t clutch cog with a 68 primary. My Stella has a 22t clutch cog which isn't a huge difference. It is zippy and fun at lower speeds, like on winding back roads with a max speed limit of 45 mph.

I also have a a stock 200 engine with taller gearing; a 23t clutch cog with a 25t primary. In comparison to the Stella, the acceleration is more sluggish, but it cruises nicely at 55 mph+.

It sounds like your engine is geared perfectly for the kind of riding you do.

You are very close to your max speed on your current set-up. I have a similar mods. Eventually you may get 1 or maybe 2 mph more playing with settings, tire pressure, tucking down more, etc but that is about it.

I have the same kit and love it. When I was still plug-and-play, I was getting about 65 mph (gps) sitting upright. That is using LML reed cases.

I can't really comment on jetting. As I said in one of your earlier threads, you are breaking new ground using a 26.26 with this kit.

I can comment about gearing. What I have found is top speed in 4th is almost entirely a function of horsepower vs. wind resistance. Either you have the ponies to punch a PX shaped hole in a 65 mph headwind, or you don't. As a practical matter, changing the gearing just changes the rpm where you run out of horsepower.

Most of my riding is city streets(25-35mph). If i wanted to jet for sustained higher speed(55-60), where would i begin?

Richer than you think. Air corrector matters more than main jet here.