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Dobson110
7/4/2018 6:23am
7/4/2018 6:23am
Hi guys, just looking at swapping out my Mikuni for a keihin airstryker. I was wondering what my best option is? Getting one directly through jd jetting or am I better off sourcing a second hand one from another bike and if so what model works the best with 2007 CR250 and should I be looking at one with tps?
Thanks
Thanks
Your stock Honda ECU will not be able to operated the PWK powerjet circuit since the stock Mikuni was not equipped with one. Since the PWK powerjet is energized closed and de-energized open, the circuit will be continuously open and flowing fuel at all times which will mess up your jetting unless you block the circuit off. A lot of guys will solder or epoxy the brass powerjet jet closed and re-install the jet, or just remove the jet and install a set screw. Either technique accomplishes the same thing.
There is a guy on TT who sells pre-fabricated Throttle Postion Sensor kits using genuine Sumitomo connectors to perfectly fit the connectors you have on your Honda. Just tell him which carb you are using (The YZ, KX or RM version) and he sends you the correct connector kit. Search Honda 2 stroke forum over there.
Many guys report good results from installing a STIC metering block in the PWK.
Not a huge difference, but a sensitive test rider can tell.
The Shop
https://www.ebay.com/itm/2003-SUZUKI-RM250-CARBURETOR-ASSEMBLY/25372571…
https://www.procircuit.com/jetting-specs.htm
A lot of guys use the triple taper Suzuki needles with good results. A few guys use the Yamaha N8RJ or N3EW which are 1 and 2 steps richer than the N3EJ respectively. Again, lots of good info on TT..
Also, watch the slides when you're buying a PWK. Believe the 03 RM250 used a #6.5 which is 1/2 step richer than #7. Buying replacement slides is expensive, however you can always have a richer slide machined to a leaner number, but not the other way around.
A few reports indicate the cheap eBay Chinese knock off long body PWK's without TPS work pretty well also. Something like $50 new.
Pro Circuit actually has a good cylinder and head package for under $400. I think Vital member "H4L" has experience with that setup. Maybe PM him for his input.
However, there are a lot of other good tuners like Tom Morgan, Terry Varner, Chad Watts etc who can help you.
The ignition can be advanced 2 to 3 degrees without losing top end and improving low-mid. A worthwhile mod that costs nothing. The stock pipe is pretty good also.
https://thumpertalk.com/forums/topic/1013742-keihin-pwk-airstriker-yz25…
I plan to race mx once the bike is completed, in the early stages of the build at the moment, still cleaning everything up and trying to chase up all the parts now.
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