03 ttr125 troubles

Joined
Aug 10, 2018
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#1
Yesterday I bought a 03 ttr125 , seemed like I was making a good deal at the time. Rode it a little bit yesterday and thought the carb needed rebuilt. Rebuilt the carb today, and cleaned it up. When I started it I noticed it was leaking oil from the right side crank case gasket. So just out of curiosity I pulled the dip stick while it was running, and it was pushing a ton of air out of the hole. Could this mean pressure is escaping the combustion chamber, and the top end needs rebuilt? Thanks for any help
 
Joined
Jul 27, 1999
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#2
What you are describing certainly sounds like an engine that at a minimum needs new rings. Doing a leakdown test or less reliable but still helpful, a compression test should give you a better idea of how worn it is. The good news is it's an incredibly easy engine to work on and the parts are relatively cheap. Plus if you have to take it apart anyway it's a great excuse to hot rod that little motor, which it will respond to nicely.

While you have it apart if you take some weight off the flywheel you can really wake the engine up. I took 24 ounces off the flywheel on mine. Other inexpensive but useful mods are running a high flow airfilter with an opened up airbox snorkel along with a richer pilot jet and richer main jet .
 
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#3
I checked compression and it’s really good, right at 140lbs! The oil leak was just a gasket that was put on incorrectly. I opened up the air box, and rejetted the carb. That really woke it up! Then yesterday my fmf exhaust came in, now it sounds amazing too. How did you go about turning down the fly wheel? I have a lathe so I can do the work myself. Did you just remove some material and weigh it?
 
Joined
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#4
I checked compression and it’s really good, right at 140lbs! The oil leak was just a gasket that was put on incorrectly. I opened up the air box, and rejetted the carb. That really woke it up! Then yesterday my fmf exhaust came in, now it sounds amazing too. How did you go about turning down the fly wheel? I have a lathe so I can do the work myself. Did you just remove some material and weigh it?
Exactly. I just made a simple fixture to keep it square in the lathe and removed metal in areas on the outer rim where it seemed safe. It's fairly intuitive once you get it in your hands.