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Understanding the Keihin PW22?

Fuel System: Gas (Petrol) tanks, Carburators
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DianneB
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Joined: Tue Jun 30, 2015 5:29 am
Location: Manitoba, Canada

Understanding the Keihin PW22?

Post by DianneB » Wed Sep 02, 2015 8:31 am

Before I overhauled the engine on my '67 Dream, I had it running twice and it idled pretty good - never did try to take it on the road. The compression was TERRIBLE. On the second run, it ran long enough to warm up and the rings stuck so I did an overhaul with carb kit, new rings, gaskets, seals, etc., and converted to Probe electronic ignition.

Initially (after the overhaul) the engine was running terribly rich, "slobbering rich". I got 1/2 mile down the road before it drowned and wouldn't restart. It left a puddle of raw gas under the left exhaust and fouled the plugs something terrible.

I took the carb off again and checked all the jets - all the right size - and made sure all the passageways were open - they were. I dropped the needle from the 3rd ring to the top ring with a very small improvement and finally did some modifications to the main jet mounting body to raise the main jet in an attempt to further lean the mixture - that helped a great deal and it now runs but it still isn't right (NOT a modification I would recommend to the faint of heart LOL!)

There is SOMETHING wrong with this carburetor that I haven't found yet and it has me stumped! I have no idea what "backyard modifications" may have been made to it before I got it but there were screwdriver dents on the bottom of the slide as if someone had tried to pry the slide up at some point. I checked the jet sizes and they are close to book values so I am completely puzzled as to why it is still running extremely rich. It does start to improve at high throttle settings so it is something wrong before the 1/2 throttle point.

Has anyone found a detailed description of the workings of the Keihin PW22 carburetor, something that would help me diagnose the main "fuel paths"?

Thanks gang!

R100
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Post by R100 » Wed Sep 02, 2015 9:04 am

Factory Service Manual.

DianneB
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Posts: 287
Joined: Tue Jun 30, 2015 5:29 am
Location: Manitoba, Canada

Post by DianneB » Wed Sep 02, 2015 9:42 am

R100 wrote:Factory Service Manual.
Is there a factory service manual for the carb? The Honda service manual doesn't go into details about the inner workings of the carb.

R100
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Posts: 332
Joined: Sun Jul 01, 2012 3:02 pm

Post by R100 » Wed Sep 02, 2015 10:49 am

This is the manual I have from E-Bay.
Tried pics of the carb description pages, hope they will be readable.
(Watch out for any differences between PW22 and PW26.)
Attachments
manual excert - carb 004.JPG
manual excert - carb 004.JPG (125.33 KiB) Viewed 4461 times
manual excert - carb 003.JPG
manual excert - carb 003.JPG (138.21 KiB) Viewed 4457 times
manual excert - carb 002.JPG
manual excert - carb 002.JPG (130.32 KiB) Viewed 4457 times
manual excert - carb 001.JPG
manual excert - carb 001.JPG (191.13 KiB) Viewed 4461 times
manual excert - carb 005.JPG
manual excert - carb 005.JPG (121.39 KiB) Viewed 4469 times

R100
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Posts: 332
Joined: Sun Jul 01, 2012 3:02 pm

Post by R100 » Wed Sep 02, 2015 11:09 am

P.S. The shop manual on Bill Silvers CD appears to be the same.

DianneB
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Posts: 287
Joined: Tue Jun 30, 2015 5:29 am
Location: Manitoba, Canada

Post by DianneB » Wed Sep 02, 2015 12:00 pm

Thanks man, that helps!

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