Modern Vespa

OK so here's the jetting update.

Started with 140/BE5/108. Definite improvement on the low throttle weirdness, so the BE5 is a keeper. Tried moving down to 105, it didn't feel so good. Then I ran back into one of the things I'd forgotten about this particular carb - the front air filter screw has been stripped at some point, so you need a fastener that's a bit longer than normal to grab the remaining threads. During my 105 run, the air filter got all loosey goosey and I had to pause the work to go to Home Despot and get some longer screws.

Returned to it and tried 105, just didn't feel right. Back to 108 and around my bigger test loop of about 11 miles. I actually had lower top speed (50MPH), and it still just didn't seem like all was correct. There is a kind of cyclic power surge at full RPM, it's like power is sort of on for 2 seconds, off for 2 seconds, sometimes longer, sometimes shorter, but something isn't right.

A quick look at the plug said I wasn't crazy rich, if anything maybe slightly lean.

I tried going lower to 102, that was nothing different. Back up to 110, nada. This engine seems to run the same with jets between 102 and 112.

So screw it. In goes the 120. Now there's what rich splutter on this engine actually feels like! I hadn't actually experienced it yet on this one, though I thought I had. 118, still rich. 115, just a tad. So back to 112 and it's relatively clean. This means my 160AC running was all on the lean side. I also did drilled filter for this last iteration (stolen from my Stella motor, will have to replace it along with the cylinder head).

The kind of poor combustion / cycling power thing at max RPM is still a thing. Honestly, I'm guessing the mixing of the charge isn't that great on this 2 port top end. Also, probably would like that rotary valve opened up more.

At any rate, the max speed on my 2nd go around of the testing loop was 53MPH. I'm getting about 6500 RPM in 3rd, about 6000 in 4th. It's jetted safely, I even did a bit of acceleration down hill (holding my breath).

Current jetting 140/BE5/112 with 55/160 idle. Timing is at 22*.

This cylinder is not gonna make plaid, but I didn't really expect it to. The bike is cleared for local rides and shenanigans.

Next up - I think I'm gonna repair this bench seat that I got during all my parts trades. It's not a bad tear, and getting the cover off is easy. The repair should be simple. The saddle seat has me a bit forward, and I have tiny legs, I can't imagine how tall people do it.

If the main jet is more or less correct, it's likely to be something to do with the 2 port poor scavenging issue.

55/160 pilot although will run acceptable, is not going to be best suited jet. Try 52/140, I think this will be better.

That's a nice seat. I like the vintage look of the original saddle seat. But I'm 6'2, all in the legs and I feel jammed up against the legshield.

I've already decided the pinasco will be happening

https://www.sip-scootershop.com/en/product/racing-cylinder-parmakit-sprint-gt-super-177-cc-5771600-for-vespa-125-vnb-gt-gtr-1-super-150-vba-vbb-t4-gl-sprint-1-super-1_80527000

That thing looks wild. The ports are huge, probably need to weld new material to go that big. I'm intimidated just looking at it.

Wow - I wonder how this compares to the ole Pinasco 177 2-port kit?

That thing looks wild. The ports are huge, probably need to weld new material to go that big. I'm intimidated just looking at it.

It ships with two base plates.

I did actually see that. I am just not sure I want to go chase the dragon again.... Anyone use one of these Parmakits yet? I want simple. My Malossi 166 on the PX taught me that simple can be fantastic.

If you want three port performance, build a three port motor.

Do they have two-port racing classes? That's the only real use case I see for a top end like this one.

Plus - going the 3 port route leaves me with 2 2-port motors sitting about. I want to make use of them, so this seems smart.

And if you need any encouragement staying 2-port ...

I love my quirky 2-port Pinasco 177 that go WOT all day. Well, maybe not all day, but long runs and twisty roads.

Just remember, the Pinasco 2-port runs a bit hot because of the internal 3rd port. That's been my experience anyway...

what are you running for jetting and timing? what exhaust are you running? carb?

I did actually see that. I am just not sure I want to go chase the dragon again.... Anyone use one of these Parmakits yet? I want simple. My Malossi 166 on the PX taught me that simple can be fantastic.

And if you need any encouragement staying 2-port ...

I love my quirky 2-port Pinasco 177 that go WOT all day. Well, maybe not all day, but long runs and twisty roads.

Just remember, the Pinasco 2-port runs a bit hot because of the internal 3rd port. That's been my experience anyway...

Not perfect but the scooter isn't either!

Definitely passes the "better than it was" test, which is all you can really hope for some days.

Lookin' good, John

Not perfect but the scooter isn't either!

Aaarrrgggghhh

That sucks. Maybe you can take the mechanism out of a p200 seat?

No lathe required. Just go old school and hand job it. Use Your grinder with cut off wheel to chop down the underside of the P-series post. Measure carefully, cut even more carefully. Clean it up with files and paper, re-tap threads if needed. Put nuts on the exposed thread to protect them from the wheel of death. boom done in 15 minutes.

you said hand job it

Can't have one without the other,lol

Pitch, swing, and homerun

Reminds me of a Meatloaf song ...