hello!
Im also raping Hyosung sf50 scooter,
and I know this requires really big patience 8P
installed:
malossi 70cc group
technigas exhoust pipe
lightweigt roller comp
air intake
malossi reed valves
and with such modification spent riding three seasons. had luck to change piston maybe three times already.
first time was mistake with fuel 95 instead 98 ;/ other times it was like piston ton covers with carbon and oil mixture and this mixture makes rings to stuck on piston and than piston starts to burn ;/ so I started to put less oil in to gas.
this scooter does have mechanical oil pump but this stock pump have been sucking oil for 50cc cylinder, so I added manually 50ml to (5L) gas tank. this time anyway piston rings stuck and broke..
so I bought new one again and decided not to put oil to gas anymore and after bout 1500 km now i opened engine again to see what is the picture. (I had many accidents so I had luck to meet each side of this scooter
)
so after opening I saw this: piston top bit covered with carbon but dry without oil. and cylinder head covered also (not so much as earlier times) but covered with abit oily carbon.. Im using NGK BR8HS
picture here:
would be nice to hear if someone have some suggestions bout what can cause this 'burning'
but no adding oil caused to work some engine parts more loud.. so now Im gonna make oil pump work with bigger amount or disconnect it and use oil gas mixture only.
with this chance I also cut exhaust pipe a half to clean all oily carbon stuff from inside, sand it and paint it. also to change the stuff inside little canister in the end of it (oh terminology
)
planing to put other shock breaker (if the right name, sorry) with manual inflation. just used one from some other motorcycle.
to change tires and regulate to get richer mixture or also to change carburetor to bigger one.
later Ill put some more pictures of what Im doing.