Working on a 1987 KX250. Bike has a replated cylinder with overbored piston, fully cleaned powervalve system with fresh seals, Boyesen RAD valve, new pre-oiled air filter, stock pipe with a few minorish dents, stock muffler with fresh packing.
The carburetor is a brand new Sudco Keihin PWK38 Air Striker (long body).
Jetting:
pilot: 55
main: 170
clip: middle position
slide: unknown no markings
needle: unknown no markings
Premix is at a 32:1 ratio (Castrol 927, it's what I had on the shelf tonight).
It sounds lovely revving when parked. Lots of bark, and crisp. What I'd consider a normal amount of exhaust smoke out the muffler. When riding, the bike feels anemic with lackluster power in the mid/top end. I know it's an older steed but it just struggles to go. If I apply full throttle in second gear from a gently rolling pace, the bike bogs out. I can pull the clutch in and rev it up, but it def feels like it is either starving for fuel or is running rich. I'm not skilled enough jetting to know how to feel the difference.
This plug read is after about 10 minutes of riding, with some full throttle attempts. It was not a WFO chop fyi.
My question also has to do with float level. I'm reading conflicting reports on what angle the carb should be. The overflow tube is at a 45 degree angle (vs more of a 90 degree bend with a similar PWK on a KTM).
Looking for any tips or wisdom on dialing this carb in.
Your plug is lean. I suggest raising your needle one notch at a time(dropping clip). You may have to go down on your brass once the middle is getting enough fuel but test it first and get back to us. Your float looks ok.
Definitely not a Japanese Keihin.
I would really need to know what slide and needle you are trying to use. I would more than likely recommend a different needle to be used, which would depend on the slide #.
I’m concerned that you didn’t get a genuine Keihin PWK. Those fake cabs can still be made to work, but they are sometimes just not as consistent as the original Keihins btw, that float should be set to 16mm
https://www.sudco.com/genuine_vs_fake_carburetors.html
Should float be set at 90 or 45 degree angle? I get different measurements at each
I have a NECH needle in my box o' Keihin parts
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Forget about the measurements. The float should be parallel with the carb body as it first contacts the seat. Your's appears to be doing just that. I wouldn't hit the panic button yet until you try what I suggested.
Your first float image looks like you have the carb at about 45 degree, with the float bar barely touching the needle plunger, this is correct. Second image sitting completely upside down, the weight of the float will push down on the plunger and that is not gonna give you the correct reading.
This is a Mikuni, the height is different than yours, shows how to measure correctly, it's just an example, but same method for all carbs.
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