Upjetting a PX 125?

[james]

I have a 96 main jet on my PX125 and am about to buy either a sterling or a scorpion/jl replica exhaust, other than that the scooter is standard. I was advised to upjet and do the usual plug chops but where do I start? Should I buy a 98,100, 102 ? I don't mind buying a few jets so I can swap them till I find the right one but I can't find a local stockist so will buy over the internet or phone so would buy a few as I need to use my scoot daily. I know every scooter is different but I just need a starting point or advice from someone that has done it themselves please. Thanks in advance, James :?

[dto79px]

go up main jet size about 10% for just an exhaust , so if your standard main jet is 96 then fit a 105 , then do a good run and check spark plug colour should be chocolate brown , if black sooty then go down a size if light tan colour then go up a size .

[james]

Thanks fo rthe advice. I have been told a 98 will do the job but 100 to be on the safe side. Obviously his advice and yours are a bit different so I still a bit puzzled. Why would the 2 bits of advice be so different?

[joey]

James, you'll notice that an awful lot of advice/opinion differs when it comes to scooters! ;D
For the vast majority of after market exhausts you need to go up 1, maybe 2, to be on the safe side, jet sizes. Any more and you'll struggle to be running at full throttle as the motor will be way too rich. So you were given the right advice to start with the 100 and work back down.
It's already been said that the colour you're looking for on the plug is a nice chocolate brown.
Ride your scoot for a while to get the motor up to working temperature then give a good thrash for a minute or two, when it's safe to do so turn off your ignition, pull in the clutch and coast to the side of the road and only then check your plug. You want the reading to be how your scoot is acting at full throttle so no use having a quick bimble round town and then checking it as it will give a false reading.