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Calling all 2001 Kx125...!

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I just wanted to share some jetting experienced I just had with my sons 2001 KX125. I did a research all over and came up with something close and maybe pretty much will be working for 500 to 1000 elevation.

The bike is Stock

Original Head and Piston

Main 360

Pilot 50

Air Screw 1.5

Needle Stock

Clip 4th (stock)

Compression 135 PSI

Gas 92 octane

Mix 32:1

Motul 600 (discontinue)

The bike ran so so, mid range to the top was sputterry and flat. I mean you don’t get the clean speedy rev from the engine. At first I felt I might need a new top end since the top have not been replaced by the two previous owner. I do not see nick marked on the top end nuts. The bike was purchase for $800.

Suggestion was to replaced the Main to 370 and Pilot to 45. I found some old pilot jet on my collections and decided to just get the Main 370. The package came and proceeded to take the carburetor apart. Later found out that the 45 pilot jet that have was not the same ( it would not thread in), replaced back the stock 50 and decided to adjust the needle clip to #2 from #4. Started the bike with two kicks and NOT needing any adjustment to the idle and proceeded to warm up. Test rode the bike and the bike pulls hard, I mean almost a different bike. I’m 240lbs guy and this just pulls me well, then called my son to try it. He said same thing, almost different bike. The exhaust smoke was very minimal, previous to this, there was a lot. It revs pretty quick from takeoff lunch with me on the bike. Too bad the weather here in Seattle is not cooperative at the moment. Will test ride this setup a little more before we head to Moses Lake sometime May. I’m stoke, my 1998 RM250 stallion got new shoes and handle bar. The RM was purchase for $700:banana:.


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