Need advice on my 480 big bore

[kennymiller]

I reancently put a 480 big bore on my trx 450r. The head is ported, hot cams stage 2 cam, JE piston 13:1 ratio, white brother e series pipe and header, K&N filter and jetting. I have had this motor torn down twice and we are still getting oil burning and compesion loss and top end. Any thoughts?

[mojoe2878]

have you had the valve seals checked and the valve seats checked and the angles measured to make sure they are in spec. and the springs checked to make sure they are still good?
who rebuilt the engine? if it was the same person who did the bore job then there is a possibility he is boring it a little past the recomended piston to cylinder clearance. if the piston ring gaps werent installed right then they would make you lose compression and burn oil too.
what kind of head gasket are you using with the hig compression 13:1?

[kennymiller]

Max Power did the bore and head work. I have a company in Simi Valley,where I live taking a look at it now. The intake and exhuast valves were leaking as well as the rings, but the head has been machined and in the last leakdown test the valves weren't leaking anymore and the rings were fine as well, but after about 15 minutes of breaking in the motor, it started to smoke again. LB racing (company where I live) did a leakdown test again on last Friday to find the valves were fine, but the rings were leaking again. They told me that it looks like the oiling holes at the oil ring seem to be to high and oil is getting above them. Keep in mind that JE this JE piston only has one compersion ring. LB says that the bore seems to be fine compared to the the piston diameter. I'm using a cometic three layer gasket.

[mojoe2878]

Originally posted by kennymiller
Max Power did the bore and head work. I have a company in Simi Valley,where I live taking a look at it now. The intake and exhuast valves were leaking as well as the rings, but the head has been machined and in the last leakdown test the valves weren't leaking anymore and the rings were fine as well, but after about 15 minutes of breaking in the motor, it started to smoke again. LB racing (company where I live) did a leakdown test again on last Friday to find the valves were fine, but the rings were leaking again. They told me that it looks like the oiling holes at the oil ring seem to be to high and oil is getting above them. Keep in mind that JE this JE piston only has one compersion ring. LB says that the bore seems to be fine compared to the the piston diameter. I'm using a cometic three layer gasket.
i dont know that much about the JE pistons. i have always used wiseco and have not had any problems like this before.
you may want to try and switch to a different piston and see if it helps.
did the shop also check to see if the valve seals could be the cause for oil to leak past and get into the cylinder. bad valve seals will cause it to smoke but wont effect the compression.
the flex steel gaskets are the best ones to use in my opinion.

[kennymiller]

Thanks for your advice. I have already found a company that has a wiesco piston and will be ordering that today.