New to Denver PWK Carp jetting

R0dd

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Jul 23, 2017
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Hello everyone,

I just moved to Denver and just bought a Keihin PWK 28mm Carb. I have a fresh top end, V force 4 reeds, new Toomey Exhaust and running topless. Anyone know what's a good place to start for jets?
 
this is a good one, mile high elevation will require considerably less fuel than sea level jetting.
I'd look thru this thread and see what others are using for 28mm PWk's, maybe start there and plug chop down to adjust for your thinner air at that elevation.

PWK 28mm @ 4000'+ elevation....
https://www.blasterforum.com/threads/what-jets-are-you-using.28981/#post-341244

other helpful threads:
https://www.blasterforum.com/thread...ir-pressure-and-how-to-jet-accordingly.39872/
https://www.blasterforum.com/threads/adjusting-your-airscrew-pilot-jet.51060/
https://www.blasterforum.com/threads/how-to-plug-chop.53237/
 
What is the black plastic screw (idle screw?) supposed to be set at? I put in a 45 pilot and 148 main to start and plug chop (brass air screw set 2 turns out) but every time I start up the bike the RPMs sky rocket and I have to shut the bike off in fear that I'm gonna blow it up. Its got fresh gas mixed 32:1 with yamalube 2 stroke oil. Whole engine was freshly done top and bottom with all new seals and I eliminated the TORS.
 
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What is the black plastic screw (idle screw?) supposed to be set at?

the idle screw should be barely holding the slide open
in your case turn it out more to let the slide drop as far as it can and try a restart, then slight turns until it lifts the slide for desired idle.

make sure you have the recommended slack in your throttle cable too, and it is routed correctly from throttle to carb, the cable can hold the slide open too far also.

I'd turn that airscrew in to 1 or 1.5 turns out to start also, until you can get it idling correctly, then do the process of tuning the airscrew for highest idle to figure out what pilot is required ....
https://www.blasterforum.com/threads/adjusting-your-airscrew-pilot-jet.51060/
 
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I snapped some pics of the slide on the carb, is this position why it’s idling so high? I’m new to this carb and I can’t get the slide to come down any further.
 

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that's open like 1/3 throttle, and is why it's idling so high
take the cable off and back the idle screw out the whole way to see if it slides down all the way
has to be one of those 2 holding it up that high, it should be down so far you doubt it's flowing any air, but it will

edit: is this one of those that the slide can be put in backwards ?
 
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that's open like 1/3 throttle, and is why it's idling so high
take the cable off and back the idle screw out the whole way to see if it slides down all the way
has to be one of those 2 holding it up that high, it should be down so far you doubt it's flowing any air, but it will

edit: is this one of those that the slide can be put in backwards ?
 
Now that its idling fine its doing thiso_O:

When I hit the thumb it bogs out a bit then I’ll hit it right after and it revs fine.





 
Try turning the airscrew in 1/8 turns at a time to see if it clears up, if not it's likely a needle or even wrong slide # :(
I know the 33-36 pwk's like DGH or CEL needles and a #6 slide to work correctly

what needle is in it now ? try lowering the clip to raise the needle and feed it a little more fuel for the pilot to needle transition you're bogging at now.

get all your info and post it here in one post ..... pilot #, airscrew turns out for highest idle, needle #, main jet #, and slide #
 
I have the stock slide and needle in there, I didn’t know I had to change them out.... I tried to turn the air screw in but then it started to idle a little too high. I’m assuming the way it’s idling now is good. At least it sounds good to me. What slide number and needle do you recommend?