87yz125t

I have a 1987 YZ125 that has no power in the top end, and not much in the low end, the carb has been rebuilt and jetted to go along with the fatty pipe i bought, it also blows fuel/oil out of the exhaust, which tells me that its either getting way to much fuel, or not burning what its getting, could this have anything to do with the power valve? when i got the bike none of the linkage for the power valve was connected, so i'm not sure if its hooked up properly or not.
please help

tigmaster

Is it hard to start? If so, is it hard to start cold, hot, or both? No power usually indicates a low compression. What is the gas/oil mixture right now? A lot of the older bikes have a tar-like oily residue that flows from the end of the silencer. It is actually a real thing and even at the proper gas/oil mixture they can do it. Just describe everything a bit more and answer my questions and we will sort this out in no time.

__________________

Check Our Latest How-To Here

tigmaster

I did not see the last part about the linkage though. What do you mean none of it was connected? Did you connect it up? If you are concerned with that, we either need pictures posted or you can purchase a shop manual for the bike.

__________________

Check Our Latest How-To Here

87yz125t

The bike has a fresh ring on the piston and the cyl. has been honed. I bought a fmf fatty gold series, jetted the carb to 290, and the other recommendations from fmf, which is the needle clip in the 3rd position, and the air screw 1.5 turns out. The floats are at the factory setting of appx. 11mm. The bike is hard to start, sometimes it just will not run at all, but it does have good spark. it has a little bit of power in the bottom end, but really craps out at maybe 1/2 throttle and does a little sputtering and popping. There is also what i think is an excessive amount of oil tar coming out of the exhaust, my friend used to have this same bike and his didnt have a drop of oil coming out.