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2003 YZ85. 2004 KX85
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I bought a used 04 KX85 for my 14 year old boy to learn on. It's been over 30 years since the last time I tinkered with 2 strokes..I feel like an old dog trying to learn new tricks.
The bike seemed to run pretty good when purchased with no starting issues, but it sat for about 3 months, probably with fuel still in the carb, and now doesnt want to start up when choked. I assume I will need to take the carb apart and rebuild. Also, I noticed that there was a tremendous amount of oil in the silencer, so I repacked it..started seeing oil appear at silencer shortly after. Engine seems to have compression and runs well .not sure if I have blow by happening ir possibly oil build up in the pipe from prior to my ownership. I have been trying to get an understanding of the pwk28 keihin flat slide carb, as it is the same carb on both my kids bike(other is a 2003 YZ85 ) but I feel like everything I have been doing is a "poke and hope" attempt...if anyone could point me to a good thread for this particular carburetor rebuild/tuning that would be great.
 

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First poke the wire from a bread twist tie (after stripping off the plastic) into the idle jet to clean it out.
Then just push start it downhill and once it's running put it into neutral and mess with the idle air screw till it has maximum idle RPM and then turn it in 1/2 turn. If that final setting is less than 1 turn out then you need a richer idle jet. If that final setting is more than 2 turns then you need a leaner idle jet.
For my complete jetting guide go to 2 Stroke Carburetor Tuning
Excess oil probably means you're just adding too much. Typical ratio for completely non-synthetic oil is 25:1, for semi-synthetic is 35:1, and for fully synthetic is 45:1 for small bikes (higher ratio for bigger bikes because they rev lower). Look at the viscosities of different oils at www.dragonfly75.com/moto/oil.html
Totally non-synthetic oils have the lowest viscosities which is why more oil is needed, and fully synthetic oils need less oil because of their high viscosity.
 
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