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Old 12-30-2017, 12:34 PM
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Default 1996 CR500R PWK38 Air Striker jetting starting point

     

dogger, are you still here? (and any others with PWK38 AS on CR500s)

I am working on a new CR500R engine build (1996 motor built new from the ground up) for an AF project (2009 CRF250R frameset). I have a 1999 CR250 airboot...modified to fit the CRF airbox like many do.

Here are all the motor details:
- 1996 CR500R Motor
- New HotRods balanced/trued crank matched with Wiseco 90.00 mm Pro-Lite piston
- Boyko Racing mid/upper-mid ported, 1.0mm overbored cylinder (Ted used to do some motors for Rick Johnson, etc.)
-Boyko Racing matching modified head/squish
- 1999 CR250 airboot into CRF250R airbox with adapter
- Boyesen Rad Valve (RAD-03A)...it was free
- Pro Circuit pipe (PH89500)
- Pro Circuit 304 silencer
- PWK38 AS bought new as Honda OEM from 2000 CR250R (Honda P/N: 16100-KZ3-J21)
- close to sea level

dogger, your engine builds are legendary, and I know you swapped to a final destination of a PWK38 AS for your CR500AF once you got everything sorted out. What jetting did you arrive at even though you were using a Tassanari reed cage? I'd like to start there and then do my plug chops to perfect it.

Any help is appreciated from all. Thanks.
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Old 12-30-2017, 07:22 PM
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I am no expert on this, but I think I would look at jetting on the latest kx500 and use that as a starting point.
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Old 12-31-2017, 06:29 AM
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I think the latest kx used a 39.5mm carb. Generally I would stay with the same jetting used currently at least the main jet as a starting point. I would put something rich like a 168-172 main, so you have some margin of safety. I am not sure if the pilot changes much. I would use a 42 or 45 pilot as a starting point. pretty sure you can use the same needle as the pj? 1368. Hopefully someone else will chime in. That should be kinda close then tune from there.

Last edited by tuggy450; 01-01-2018 at 06:26 AM. Reason: Typo/spelling
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Old 01-04-2018, 05:01 PM
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55 pilot 168 main, the slide is probably a #6 which is too rich, you need a #7 slide and a N82P needle in the third position, or you can modify your #6 and make it a #7....this should get you really close to sea level and 70 degrees. The needle is available thru Kawasaki, its an optional needle for the kx500. Note: getting the slide right is extremely important!
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Old 01-05-2018, 10:11 PM
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Thanks for the input Crogg. My slide is a #7. I have a R1368N needle....55 pilot and 168 main as well. Actually I have an array of mains and pilots in both directions.
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Old 01-14-2018, 02:17 PM
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I'd 2nd the KX500 jetting as a starting point. You may want to go a size or two richer on the main jet just for safety. Its always easier to go leaner on the main gradually versus having your cylinder replated again.
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