Which is the best 70cc Cylinder Kit?

[671MTX]

Airsal, Polini or Malossi? Why? 

I'm debating on which to get for my AC Super 9. 

[Areomyst]

Out of the three, the only one that is alunimum is the Airsal.  It has more tuning potential than the Malossi or Polini.  Personally I chose the Airsal because I feel that it is the best value.  Alunimum with NiCaSil plating, bridged exhaust port, etc.  Much better bang for the buck than the others. 

Between the Malossi and Polini, I'd go with the Malossi.  They're both cast-iron, but the Polini is said to have some pretty sharp port edges.  I've used a lot of Malossi cylinders and they hold up well.  In fact, I have a customer who's scooter is in the garage now, it has over 10,000 kilometers on the Malossi kit.  He doesn't even take my suggestion to pre-mix, he just adds an extra couple ounces to the tank when filling up and lets the autolube do the rest.  The kit is still going very strong!  Another 500 kilos and he's going to have it in to de-carbonize the head, piston, and exhaust port.  He's considering having some porting work done, but haven't heard back yet on that.

I have also seen some very high-mile Airsals.  One guy I know has a People 50 which uses the same cylinder as the air-cooled Super 9.  If memory serves correctly, he's got over 14,000.  He's been through two head gaskets because another shop didn't get the head torqued down right, but other than that he hasn't had trouble out of the engine.

Now if you REALLY want to get involved, you can get a Minarelli Horizontal cylinder (for Zuma, Aerox, Jog, etc) and have it turned on a lathe at the base of the cylinder so that it fits the Kymco.  You can use a Mina exhaust with this setup also, with some slight modifications.  From what I hear, this is a really bad-ass way to go if you want to scream on the track.

I'm hoping to get over 18HP out of my Airsal cylinder when I'm done porting it.  My scooter will be used for race and show.

When it comes down to it, it's your preference.  Either of the 3 kits will be good for street use, though the Airsal and Malossi are much more tried and true than the Polini.  The Airsal has higher port timings.

Hope this helps!

~Josh

[671MTX]

Thanks for all the info Josh. 

[Chaz]

Airsal, even though it is not the most expensive.  Cast iron cylinders, like the malossi and Polini are prone to cold seizing.  This is because the piston is Aluminum and the cylinder liner is steel, they have different rates of thermal expansion which leads to the piston nipping up in the cylinder if held open for a long time.  Also the airsal has really aggressive port timing and a massive exhaust port.  When coupled with a technigas pipe and arreche 19 (or even better 21mm) carb you along with a Universal Parts GY6 no rev limit CDI, you are looking at a scooter that will see off all but the fastest 150cc 4 strokes.  We don't get the fastest 4 strokes here, they would be Gilera Runner, Gilera DNA etc.

[671MTX]

Airsal, even though it is not the most expensive.  Cast iron cylinders, like the malossi and Polini are prone to cold seizing.  This is because the piston is Aluminum and the cylinder liner is steel, they have different rates of thermal expansion which leads to the piston nipping up in the cylinder if held open for a long time.  Also the airsal has really aggressive port timing and a massive exhaust port.  When coupled with a technigas pipe and arreche 19 (or even better 21mm) carb you along with a Universal Parts GY6 no rev limit CDI, you are looking at a scooter that will see off all but the fastest 150cc 4 strokes.  We don't get the fastest 4 strokes here, they would be Gilera Runner, Gilera DNA etc.

Sweet! Let me try the setup you guys have been recommending.  Thanks!