Weird engine problem???

[trx416m]

Ok i have a 400ex that is bored to a 440 and i just rebuilt the engine about one and a half months ago. (new piston rings)
B4 i rebuilt the engine it would blow blue smoke at start up but once the piston warmed up and expands it wouldnt. Also it would gradually loose oil over time for some reason. Now it is doing the same exact thing and when i store it for one night or so and check the oil the next day its very low and no oil spots are under it. Now maybe its just burning oil when i ride it but im not sure bc its freshly rebuilt. I know the engine on my 440 gets REALLY hot when riding so maybe it just burns it because of that i really dont know. But no matter what it runs strong and never bogs or anything i mostly race 1 and 1/2 hour long harescrambles also. any suggestions r very appreciated

ps i have been running a 10w-30 and 10w-40 valvoline oil. But i just ordered some maxima atv 4-stroke oil thats 10w-40 maybe i should go thicker??

[plkmonster2]

20-50 is better, but 10-40 will work. I know for a fact that your valve seals are shot. It is a commom problem. They are letting oil get into the guides,, and into the ports. What fuel are you running? You may want to add a little race fuel to get the temps down. Also, the oil in a 400 will seep into the motor, which

[bigvforcer]

Blowing smoke at start-up and the not blowing smoke when it warms up is usually a sign of bad valve stem seals. This is very easy to fix and most dealers can get you the parts you need. I highly recommend while the head is off you go ahead and port and polish the head(if it is not already done) and get a valve job.

That should be you problem! Goo Luck

[plkmonster2]

You may also look into cam. It will wake it up a lot. The hotcams stage 2 is a very popular choice for the 440.

[trx416m]

i replaced the valve seals when i rebuilt the engine wat will a port and polish do for me besides power???? and wat exactly is a valve job???????? i have been running cam2 110 octane the last two races also

and plkmonster2 u stoped writing in the middle of a sentence on ur first response so i dont know wat u mean

[fitethesystom]

Wow if mine still smokes after rebuild.... It's gonna be one phuckin trashed bike.

Mike,