03 yz 250 leaking 2 str. oil, Power valve cleanup

I'm using 30:1 per the manual.  Leaking out of power valve, joint between expansion chamber & mufller & out of muffler.  Heard people are using up to 50-1.  Doesn't it affect cylinder/piston life substancially?

 

Thinking of cleaning power valve. Don't like Yam. manual particularly the 4 languages.  What's the procedure?  Do you have to take the head and piston off?

 

I've raced this beast twice (AMA enduro) & its considerably better than my 05 crf250r.  Shorter wheelbase, lower CG, tons of power when u want it, surprising torque.

 

Thanks

 

Yamaha (formely known as Honda by the Gages Lake ice racers)Steve.

Good luck with the philips head bolts if your bike is old =) Tap the head, or use an impact screwdriver. 

 

Other than that, everything is pretty much straight forward.

Edited by Fasz Kalap

I'm using 30:1 per the manual.  Leaking out of power valve, joint between expansion chamber & mufller & out of muffler.  Heard people are using up to 50-1.  Doesn't it affect cylinder/piston life substancially?

 

The cylinder and piston life might not be as affected as the crank bearings plus the con rod bearing. How high is your flash point on your premix oil choise? I use some red silicone sealer to seal that joint up Spooge is not that much of a problem of too much oil in the mix but rather having a too cold runing temp IMO

I cringe when I hear people using high ratios on the oil.  I have never run a bike above 40-1.  Ok, the Stihl stuff I have is 50-1 but that is Stihl oil too.  For me 32-1 for a 125, and 40-1 for the 250s.  I have run Klotz for decades, no issues.  Just run a good oil, nothing from Walmart!  If you have the cylinder off, might run a quick hone in the cylinder to retain a bit more oil.

 

Remember that the only protection ad lube the lower end gets is the premix.  Plugs are cheap, motors are not.

 

Ride hard, read plugs, repeat often!!

I also have an 03 yz250 and I run 40:1 amsoil interceptor with no problems, you might check your jets and needle position im around 3200ft elevation and run stock jetting 178 main and 50 pilot and the needle on the 1st position and bike runs excellent with very little spooge. As far as the power valve cleaning you have to remove the jug and disassemble from there.

I wouldn't worry about the power valve except if it's got carbon and sludge on it instead of just a coating of the premix oil.  It's quite a hassle to actually get the whole thing out, clean up the valve and the cylinder surfaces where it rides with the cylinder on the bike.  Some guys just take the cylinder off to do this.

I don't know how it is on a steel frame YZ250, but on my aluminum frame YZ250 you can forget about trying to get those phillips head screws out with the cylinder still on the bike.  I can't imagine a steel frame bike is much better.  Top end replacement time is a good time to go ahead and clean the powervalve.  If it's leaking, the gasket is probably just bad, or the screws rattled loose.  You could replace those phillips head screws with hex bolts to make it easier to get the cover off with the cylinder still on the bike.

Its possible just remove the radiator :) less hassle is to pull the cylinder though.

Excessive spooge is more likely rich jetting than it is too much oil in the mix. You can make a bike puke oil at 50:1, or run crisp at 24:1.

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