vespa pk 50

[tom lindley]

i have just got a vespa pk50 1995 and i have put a KN air filter on it will this make any difference to performance cos it is a gutless engine tops out at 35mph derestricted. and is there any cheap easy ways to boost performance?

[Pernig]

An air filter will not make much difference at all. The bonus of a K&N on these bikes is that they are a much better design than the original, so it is not necessarily money wasted.

You say your scooter is a '95 model? I wasn't aware they were imported into this country that late. But by the sounds of it you have the XL model, which has a much stronger crank. If your bike is indeed an XL, the cheapest way to tune I would say is to buy a DR 135 cylinder and piston kit (the crank on the PK50S isn't up to the job of the 135, so go for the DR110 or Malossi 112 I think it is). There is no head gasket on this bike, so it is a very easy kit to fit. You can even fit the piston yourself with the help of an online guide (that's what I did).

You won't get the full advantage of the 135 unless you put a bigger carb on. I would say a 19mm D'ellorto carb will go well with an air filter, 135 kit and racing exhaust. One thing I would definitely recommend is getting your carb set up right by a tuner. I used Alan Beedon at www.beedspeed.com. He knows his stuff about Vespas, also good for spares.

With your bike being a '95 bike, it might have an autolube system. If it does, I would say buy a two stroke oil measuring jug and premix the oil with the petrol yourself once tuned (I have an old one I could send you if you PM'ed me your address). Double up on the standard mixture and use the good stuff, they run so much better on good oil when tuned (I used Castrol TT Scooter). I can't remember the ratio as I got rid of the bike when I was 17.

Also if you do decide to get a cylinder kit, make sure you run it in, I'd say at least 500 miles at under 30 then gradually increase your speed. With the 135 these bikes are good for 60+. The gearing is the same as the 125 smallframe Vespas.
____________________
H100 Breaking for spares