Modern Vespa

Bone stock except for a SIP R2, 26/26 autolube carb and short 4th. Jetted to 52/120 140, BE3, 119 (I think) main as advised by Jack. Changing the jetting helped a great deal with engine vibration. New 57mm Mazz crank, new stock Piaggio top end. Completely rebuilt and leak free. Somewhat scored rotary valve repaired with JB weld.

It's slow. Easy 50, but 55 is a conscious push (GPS). Revs out to 6500 in 3rd. Won't crack 6k in 4th. It doesn't splutter rich at max revs. Low end torque is adequately stock.

When I built this engine, my tuning efforts on other engines weren't going so well, so I deliberately kept it stock. My thinking was that I was doing something righteous and pure and would end up with a cool and reliable engine. Mission accomplished, but damn…it's a dog. Even by stock standards. And I have no idea where timings and squish ended up.

I'm looking for an easy cruising 60 for this bike with a reachable top speed of 65. That'll do it for me. I would like to keep the stock clutch, brakes and otherwise keep it simple. Looking for a path of least resistance winter project that will get me there.

Thanks for reading along.

Hi, it would be kinda rich if it was a 24/24, I think stock is 160/BE3/116? That bigger carb might offset that.

I used a similar setup. Mazz crank, Piaggio cylinder/ head. I did the standard base gasket, and have a squish of about 1.26mm. I think the head had been machined down a bit.

I used the above jetting. You didn't mention break- in, but I did a lot of light to light, fast acceleration, but didn't try for any kind of speed until I had about 250 miles on it, then did really short 3/4- WOT's- like a few seconds. It's now at just under 500 miles, and GPS on short flat runs with just under WOT are about 59MPH.What does the plug look like? BTW- I also went to a 22t clutch for break in, may keep it. Feels pretty good.

What does your squish look like? Stock P200s can have some varied tolerances from the factory. I've see bikes with 3+mm stock! Take a look there.

I'm pretty sure I'm under 200 miles. I know these cylinders need some miles to loosen up. I will measure squish and port timings and see where they are.

If scooter help is to be believed, then going as bone stock does.
https://www.scooterhelp.com/tuning/vespa.gear.calc.html

Some are quicker than others. Will surely go over 70mph with the wind, down a big hill. Yours sounds ballpark ok.

Check the wot plug chop but should be good where it is.

Bolt on a VMC ranger. Keep everything else as it is. Then you should get near 70 on the flat.

Yes, definitely in the ball park. Would need to take a run at it on a straight flat road to get those speeds. VMC Ranger sounds interesting. Playing with timings/squish would require a longer crank or shortening the barrel most likely. My bet is that it's too big to be called squish.

Thanks.

Suspect the cylinder is the limiting factor here...
You have a box and plenty of carb.

FWIW - I'd be tempted to replace raise the cylinder and hunt for a 7K-7500 3rd gear. My experience with the Road II was it was perfectly happy to take me there.

Basically - I'd raise the cylinder enough not to make me miserable below 4500 RPM, and see if there was another HP to help make cruising a bit more of a wasp song at 55.

All on the same page. The limitation with the stock 200 is the cylinder and fat piston. This is exactly how my O tuned 200 project began. I wanted to see what was needed to get stock parts to do at least 70mph on the flat. Ended up being an awful lot of work. But still running well, ride it often. 17,000km since it was tuned.
Now it's easier to just buy a cylinder like the ranger. Bolt straight on. Slow becomes nimble. Reliability unaffected.

As yours is now, fitting a 60mm crank makes the most difference. Raising the cylinder and inset machine work on the head improves it. But all way more work than a bolt on VMC ranger with less result.

Double check timing? My friend's stock Rally 200 I rebuilt ( 24/24, new top end) was fast right out of the box.

well put Jack.

A 26/26 isn't stock. A 24/24E jetted in with a 160, BE3, 125 main, 55-160 is good for sea level to about 3500'+ elevation (at least for me). Flow the carb to the mixing box and then the engine case. A short 4th and a Sito+ will get all my stock P200 scooters to a true 70mph on a flat if i have a windscreen installed…but only if there's no headwind!

The only wild card for me is the JB weld on the rotory pad. Just make sure you got the correct clearance with it. I guess the Mazzi crank could be a wild card as well, but i doubt it. I'm not fan of them.

[quote="orwell84"].
And I have no idea where timings and squish ended up.
/quote]

Find out.

Timing is correct and I'm running a short 4th. I did run it for a bit with the original 24/24. Seemed about the same if I remember correctly. The rotary had some grooves in it where trash went through before I owned it. Most of it was intact. When I repaired it, I bolted the case together with the crank and a dummy bearing. I think I used a feeler gauge between the crank cheek and pad with some release film.

I agree with the kit vs O-tune argument More work and no real cost savings. Would probably need a GS piston too.

Any reason for recommending the Ranger over the Malossi Sport? I love the Sport on my VR-1 case. Lots of torque. Speed available anytime, anywhere even in 4th on a hill. If it's less revvy, it's not at rpm's where I ride, so I don't miss them.

You could measure current squish, and then get the head machined down to get the the appropriate squish. Maybe we should have a "NSM/ Vintage Speed" area. Every issue does not need new hardware thrown at it. Queue flamethrower action.

I've done three O-tunes, all made to varying degrees (two with 60mm cranks). Power and speed were increased.

In my opinion though, next time it'll be a kit. The juice wasn't worth the squeeze ..

Me wonders what the SIP Road 2 exhaust does for your build? I can't remember if i installed a R2 or R3 on one of my stock 200 (that i recently swapped into my 8" VB1) , but the engine doesn't rev up nearly as much as any of my Sito exhausts. My top speed is only 62mph. This same engine with a sito has netted me closer to 72mph when it was in my P200 frame. I would have much rather installed a Sito into this scooter, but i don't dare with the lack of ground clearance with 8" wheels.

And this is all with a huge 3mm+ squish.

Road 2 doesn't rev out like a Sito +. The midrange torque was great for a stock cylinder, though.

The VMC Ranger kit is very similar power delivery to stock, just much more of it. Malossi sport does the job as bolt on too but you already have on of those.

An expansion exhaust gets more rpm out of the stock iron too but is still slow (to Me). And will get to 70mph eventually, under the right road conditions.
I like all my scooters to be able do 70mph uphill into wind. Mostly for traffic safety. Not ridden one but from what people tell me the ranger will do this bolted on.

Thank you!

I mentioned the Malossi Sport because I'm happy with how it goes on my VR-1 case as well as the overall quality of the kit. The kits and consumables are also easily available in the USA.

O-tuning would make more sense if I had installed a long stroke crank. I understand the basics of what's involved, but don't have the time or motivation to go down that particular rabbit hole.

I agree with Jack about having power to spare. It's not really about being able to reach high speeds but having the extra capacity to maintain speed on hills and accelerate easily if required.

perfectly put. Ive explained this in the past by saying that if Piaggio had made a stock PX300 then that's what a VMC Ranger feels like, and the same thought process for a PX500 is what a Quat 244 feels like. All delivering their power at around the 6k rpm mark, just different amounts.