Modern Vespa

Well, after the Malossi piston let go last time I put the stock cylinder back on. I got bored and ordered another Malossi cylinder and piston. I also ordered the Polini cam for the 3v. I haven't seen much on the web about the cam other than a YouTube video about some shop in asia installing one on a 946.

The cam swap is easy and relatively straightforward. There are a few things that are different from stock. The cam arrives without bearings and I thought it would be better to buy new replacements rather that pressing off the old ones. I ordered the correct part numbers from AF1 but the larger of the two bearings was incorrect. Right part number but wrong bearing. I was able to quite easily tap off the large bearing from the old cam by using a large socket and setting the cam into it. For installing the bearings onto the new cam I used dry ice for the cam and heated the bearings to 250 degrees F. They easily slid on.

The other thing you'll notice is that the Polini cam doesn't use the easy start exhaust valve cam. I just deleted the extra part and installed the retainer in its place. (pictured)

I also wanted a free flowing intake so I used a cone shaped K&N filter. The part number for the air intake filter is K&N RC-2330. It's a 54mm unit. Malossi and Polini sell them also but I went with K&N. This leaves the vent breather from the cylinder head open and in need of a filter. I found the K&N filter part number K&N 62-2480 fit perfectly. It did require a little trimming of the plastic fan shroud that covers the engine but it wasn't much to trim. I didn't take pics of that...

I also checked the cylinder head for flatness and it wasn't flat. I was able to use a flat surface, thick aluminum sheet 1/2", and 800 grit sandpaper to flatten it smooth.

All new gaskets and 5w40 for break-in and then after 200-300 easyish miles I'll use some royal purple 20w50 to try and protect it more on longer highway trips.

I also had to reprogram the Polini ECU for the increased air flow and cam. Its anyones guess how well I did there but I tried a 5% increase over the Polini guidelines. I wish they posted some settings for the cam but I haven't found them.

I hope this setup will last a while, although I don't think I'm doing on any long trips again. I bought a Streetglide for that. Don't hate me too much.

If anyone has installed the Polini cam I'd love to hear your experiences.

Now the life expectancy of your engines makes sense.

Thanks for that comment. I'll be shopping elsewhere.

It would be good to add your location (more or less) and scooter model to your profile. Always helps to understand technical posts when that info is available.

I just bought two bearings. The sizes are in the workshop manual , then one goes to SKF catalogue.

small one 12mm x 28 x 8 = SKF 6001

large one 25mm x 42 x 9 = SKF 61905

I could only get shielded ones with 2Z suffix but it is easy to pry the shields out with a push pin!.

Haven't tried the cam yet. 3v but not Polini (or maybe it is a clone?)