Modern Vespa

Hi Guys.

I was wondering if anybody can help.

I have a Vespa vbb 150 (bajah)

It came with what I suspect to be a px125 engine.
The casing only allowed me to fit the pinasco 3 port with same size ports.

There was no extra room to burr out larger ports

So as a standard px125 setup it was reliable but slow.

I purchased the following.

Pinasco 177 3port cast iron.
Pinasco 24 - 24 which came with 118 main jet.
Sip JL exhaust

I started straight away and without giving it to much throttle straight away a big change in performance.

But that did not last long.

I have run bikes in before so no not to keep throttle at a constant or Rev to hard. I also added a little extra oil to petrol.

The bike has soft seized twice and luckily will still start.

I am noticing pinking noise around 3/4 revs.

I know if I ride it in or past the pinking noise it will try to seize.

So I have tried a larger main jet 122

And took the timing from what I thought was recommended at 22-23 back to 18.

This helped slightly but no joy yet.

I have ordered a new cdi as precaution.

Any ideas appreciated.

Thank you.

In a 2-stroke engine, the washing phase inside the crankcase affects the operation / performance, without knowing for sure what type of engine it is (putting the code and the serial number stamped on the engine would be useful) you can do all the experiments you want but you would waste time and money.
Having a technical approach starting from the beginning is essential.

Hi.
I have had trouble identifying the engine
The chassis number and logbook clearly ages the bike 1969 but the engine code is not giving me any clues.
As the bike came from India which knows it's history.

The engine number is 955664 which does not equate to any records I can find I would say at some point sombody has most likely made that number up and built an engine from spare parts.

I'm pretty sure the engine is not the original one.

It has an electronic ignition and its 4 speed.


Like I said the engine was reliable before the upgrade.

Thank you for your reply.

Take alot of pics and post them on the NSM side. Also, the VBB was on made up until 1966-67, so something is off.

Hi. It is a bajah.
I know it's not a fully authentic vbb but I like it for what it is.

Great news I found the problem to be the pinasco kit comes with no head gasket and it looked like it was leaking slightly however tight the head was.

I made a copper gasket this fixed the leak and stopped the pinking.

So the pinking would have been leaking head or less of a squish.

Either was I'm happy it's running well again

Thanks for your replies.