Modern Vespa

I was given a Polini 166cc upgrade kit for my wife's ET4.

Is it worth it?

Any downsides in reliability?

It has about 4200 miles on it.

What do you guys think?

How much do you think a shop would charge to install it?

Just looking for opinions, because if anyone knows...it's you...no not you, but you right there...reading this!

So you want your wife to go fast, crash, and burn?

I don't think Polini make a 166 kit for an ET4 should be a 190 kit. From what I know Polini make a 177 for a px or old school 150cc 2 stroke and Malossi make a 166 for the same engines but neither will fit the ET4. In my opinion even if it is a 190 that fits the ET4 don't bother unless you are ready to loose resale value, buy an expensive expansion chamber, ride a noisy scooter that will annoy your neighbours and take a really reliable little scooter and possibly make it unreliable, you will also likely want to change your variator and rollers then scooter will have to be reved off the line everytime you get going with No top end gain to speak of. You will wear belts and tires out sooner, but hey it is your bike do what you like.

I agree that a 166cc kit is unlikely to be for a 4T Leader 150, but I think your assessment of the potential of a 190cc kit is overly pessimistic if the installation is done properly.

First of all, expansion chamber exhausts are generally only used on two-stroke engines... his is a 4T. A freer-breathing (and likely more expensive, unless you go with a Sito+) exhaust system would probably help unlock the horsepower potential of the kit, but it would still make considerably more torque even with the stock exhaust. With a pipe like the Sito, the bike will probably have a deeper exhaust note but not be much louder.

There is also no reason why you'd need to get rid of the stock variator, although it would likely have to be re-tuned with optimal roller weights. A performance variator is an option, of course, but high revs off the line are usually a matter of choice to compensate for a LACK of torque, not as a way to utilize the increased torque that comes from larger displacement.

There might be a bit more belt wear and some decline in fuel economy if the additional performance is used aggressively, but that is a function of how you ride it. Likewise with tire wear.

Top speed would be unlikely to increase much unless overall gearing is changed. Taller final gears are available for $150 or so.

There are probably a half-dozen or so folks who post regularly on here who have put large displacement kits on Leader 150s, and I don't recall hearing of any negative effects on reliability if the installation is done correctly and ancillary performance options are chosen wisely with an understanding of how the whole drivetrain works as a system. The effect on resale value will depend on the nature of the customer pool if the job is done right.

I'm probably going to do this mod myself eventually, but I'd prefer to find a spare salvage engine so that I can do the kit on the bench at my leisure and then do a quick swap of the engines, rather than having my scoot out of commission for a while.

I have the Malossi 190 kit in my LX. The kits made for these engines have been around for some time and have withstood the test of time. These are quality parts that, when properly installed, won't sacrifice longevity or reliability.

Whether or not to install the Pollini depends on what you expect to gain. Cost of the install may run between $250-$350 depending on labor charges at your dealer.

On its own, the 190 kit added a little more oomph-better acceleration off the line, extra power on hills, with a passenger and about an additional 5mph on the top. It does have more of a growl, but the noise isn't significantly more than stock. It won't turn your ET into a rocket, but it will feel as if it spent the summer exercising and lifting weights.

The benefits were greatly compounded when I later added a Malossi Multivar. I've tried a couple weight combinations but have found for the performance results I want (better top speed and good mid-range acceleration without losing much off the line), the 11.5g rollers are best. I'm sure I could get great off the line acceleration with light rollers, but as is I've got enough torque that I popped one accidental wheelie. That's enough for me.

FWIW, I didn't play around much with varying the weights in the stock variator so don't know how much that would help.

With the final addition of Heidenau K61 tires, performance is much better than a stock 150.

I have almost 19K on my LX, with roughly half of that with the kit and Multivar. I've only had two mechanical problems, ever: needed a clutch bearing replaced and broke a hose on my secondary air system. No big deal.

Thanks for the response guys!

I will have to double check that it is actually for an ET4.

It's still factory sealed...so I will do some research!

Thanks again!