oil in air filter

[drxracing]

i have a little problem i have 90cc 05 drx a/c and after 30mins of riding the air filter is wet with what it looks to be oil what do you guys think would do this or is this normal i use caster 927 @ 36:1 any help would great

[JIM GRACE]

how is it running?? and what type of filter...
the oil is the same as most of us run..
is the oil injection still in place..

brandon's dad #55

[hotquads1]

blow-by can cause this, check the compression and check the conditions of the reeds,
marc

[drxracing]

i have uni and runns good till the filter gets oil in it then take off is
a little slugish the oil injecter is removed i have the carbon fiber reeds in it it never did this befor just started when i put the 53mm bore and piston in it i got stock carb with a 130 main jet it
runs a little rich i need a 115 main jet

[hotquads1]

what brand is the cyl kit and have you done a compression test , alot of cyl kits are not even close to being correct , to bolt on out of box , but compression will be an indicator. going from a 52mm cyl to a 53 mm cyl should NOT require dropping the jet several sizes. keep in mind there is no oil in the engine , only in the gas , so your issue is most likely an abundance of fuel being blown back into the filter and the gas evaps and leaves the oil residue. If this occurs in just 30 min of riding there is a problem. You say the bike runs well for the first few minutes, so jetting must not be off very far , but when the air filter gets clogged with oil and restricts airflow you are running rich for a lack of air not due to jetting . there are not many items that can cause the air flow to reverse and carry the fuel out of the carb and into filter when velocity is sucking it into the engine, carb float over flowing ? but I assume the carb was working well with other cyl so would it not be my first guess. A damaged ring? not tight enough clearanceat head (squish) ? Broken or cracked piston skirt ?
marc