Modern Vespa

ok .Ill try to be clear. 79' vespa p125x. new mallossi 166 kit, JL pipe and spaco carb(i forget size). Reputable vespa friend/mechanic( i think) throws everything on. notches crank, ports etc. Starts right up. within 1 mile I soft seize. Thinking i may have ran out of gas I turn it to reserve, since maybe tap was malfunctioning, and it starts. never brought it past 3rd gear and not over 40mph. Next day, when not freezing rain, I bring it into 3rd to 4th , running at about 45mph. Soft seized again, i try to get it home and soft seized again. Never ran high rpm or ran hard at all.Total miles on new kit about 8miles. Brought it to friend/shop(who kitted it) and we open it up. Aluminum smudge and slight grooves on barrel. piston has some pitting and grooves mainly on bottom. I barely touched the scooter. Sorry i dont have pics.He has alot of pride and wants to blame the fuel tap for overheating since its a stock tap. I dont believe that. SOO.. can i clean up cylinder and just get another mallossi 166piston. I mean without pics what would be my best options. This is awful since I already payed the guy big bucks. If I pay for a rebuild and within 1 mile it seizes?! well you get the picture. PIST

I don't get how a fuel tap can overheat, it just allows gas to flow.

How does the spark plug look?

Your jetting get increased for all the changes you made? You didn't say & sounds like you're running too lean. Search & read if you skipped this step.

Also consider getting a CHT, look here.

Hello

Plus 1 on the jetting and were the rings gapped, if you were running at freezing temps that have stopped seizing almost at once

Grumpy

sounds like you might need a cooling fan and a heat sink for that bad boy if it's overheating to the point where performance is dropping.

all kidding aside, start with the easy stuff: jetting, timing, air leaks

if you trust the guy that did the work, take it back to him and ask him to make it right. if not, find another shop and be ready to drop some dimes again.

-g

A stock tap will easily handle that, and more. Pull the hose off the carb and see what kind of flow you're getting so you're in a better position to prove him right or wrong.

Did he do everything, or just do the work and it was up to you to finish re-assembly?

What jet size are you running?

Might be worth asking him what clearance between piston & bore, and what end gap he set on the rings. Just to find out that he actually checked those things.

That reminds me when I had my Pinasco 215 and I soft seized like a half a dozen times before it disintegrated like blue cheese. I had a bunch of vespa friends and mechanics trying to find the right spot for jetting but it was just a piece of garbage kit.

Same thing, it would start fine and it would over heat fast, one time it melted my plastic cylinder shroud. I never knew why my kit was garbage, all I know is that the stock cylinder ran better.

The one thing I highly recommend is changing the oil to Motul 710 or 800.

Check the carb base gasket. Some have a hole for the autolube some dont. You said you replaced the carb you may have a gasket that doesn't have the extra hole and thus youre not getting any oil. As for the damage I'd try to just clean up both the piston and barrel and see what you have. At least until you figure out why you are seizing.

have Pattric up in P-town make it right
he used to run P-town scooter shop and is the man to talk with

if is was him I don't think this would have happen

is this the cast iron malossi kit...??

any good builder would make sure all is perfect before giving a new kitted scoot back to the owner and would stand behind their work.

the piston to bore clearance should have been checked
the way the top end is scratched up can tell you what happened

if the tuner didn't port it correctly for the pipe used then things like this happen. Timing should ave been changed too.

those JL pipes need the jetting to be upped a great amount not to mention the malossi kit.

https://www.facebook.com/pages/Ptown-Scooters/175090774756

got a reply from a pal who has same pipe and knows whats is what

"If he is running the JL pipe than the carb is most likely the issue. Grambo said it right with the float valve. The stock neddle valve is going to be way too small. He's going from a 100 mpg bike to a 40ish mpg bike."
- gearless24