G'Day All, I have a Kymco ZX50, it was having starting problems pretty much since we bought it in January
of 2009. It was built in September of 2007, so it was still quite new. When my wife had finished with it I was
using it but it was quite slow. While looking on the interweb I found this forum and was really inspired by the
help, advice and assistance from the people on here. It was starting to look like the engine was getting tired
so a new cylinder kit was looking like a possible solution. Well, cylinder kits, there are a lot more out there
than I would have imagined. Most people on this forum swear by brands such as malossi and polini but as I
don't have a lot of money to spend I was looking for more affordable options. I found a cylinder kit on
ebaymotors.com for $135 with free shipping. I bought one. When I installed it on to the scooter it over heated
within about 10 minutes seizing the piston. I added 100ml. two stroke oil to the fuel tank to compensate
for the larger cylinder. It still seized. I tried to drill out the jet in the original carb but with the stock airbox was
no good, it would not run properly. By this time I was quite concerned about destroying the cylinder so I
waited until the new exhaust and 24mm OKO carb arrived. After fitting these the improvement was massive.
Still running lean, the OKO carb had a #107 main jet. Finding out that these carbs use a Keihin type jet I went
to my local bike shop and found that they have a fair range of them, things were starting to look up. I tried a
#120 main jet but still not quite right, after trying 125 and a 130 I jumped to a 140, too far, so went back to a
#135 but that was a bit too big, so tried a 132 which was pretty close. I am currently using the #130 with the
carb needle at the second from lowest setting. Though not perfect, the scoot is running pretty damn good now.
I have also changed the pilot jet from a 45 to a 48 (the next one up at the local shop).
I have also replaced the front variator with a race variator from scooter assassins, less than $40 delivered
the change is just incredible, smoother power delivery and better acceleration, now the speedo needle goes off
the dial and half way through the fuel gauge. Before I started all this the scooter would do between 70~75 kmh
as indicated on the speedo, after adding the bridge to the C.D.I to cancel the rev limiter it would go to just on
80kmh, but the poor thing would be screaming. With the larger cylinder it revs out freely and doesn't sound like
it is overdoing it.
None of this would be possible for me without the help and encouragement I received from the people on this
forum, in particular zombie and Shaka, to these people I am truly grateful.
