41.5mm PWK Carb

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AlisoBob
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41.5mm PWK Carb

Post by AlisoBob »

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So , I go to Sudco to pick up some goodies.. and a 38mm PWK A/S for Uncle Cracker..... When I get there, John tells me the A/S is out of stock.

While he's gathering up all the goodies, I fumble through the Sudco catalog, and come across the new FACTORY machined 41.5mm PWK. Guys have been having their local machineshops bore 39mm PWK's out from some time, buy only recently has Keihin been offering this service directly.

John gives me a price I cant afford to pass up, badda-boom..badda-bing... its mine.

The machine work is beautiful, I think they hand select the castings to make sure that no "daylighting" occurs during the machine work process.

So, I jet it up like a 39mm... how's it run? Like Shit!

HUGE flat spot , right off idle.... So huge that when you whack the throttle, nothing happens... like you pushed the kill switch. The carb signal has obviously been compromised in the machining process. SUPER LEAN with the trusty DGN needle in there.

After goofing around for an hour.. heres where I left off "guesstimating" where the jetting needed to be for the ride out at the Pinnacles.....

Pilot: #40

A/S: 2 turns out

Needle : DGK ( R1469)..clip in the middle position

Main: 172


How did it run? SWEET! ZERO loss in bottom end responsivness, couldnt tell about the top end as I never got past 4th the whole ride.... but it felt pretty zippy.

Turns out I was very close on the jetting.... I would pop in a #38 pilot, turn in the A/S 1 turn, and move the clip up 1 notch to lean it slightly

Overall rating.... 4 out of 5 wheelies! Its Good product......, keep in mind its not the greatest bang for the buck if you already has a 39mm PWK installed.

Should run hard out a Pismo in a few weeks..... We'll see!





:wink:
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dannygraves
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Post by dannygraves »

Damn it Bob, I promised myself that I would leave my gen-4 stock....... now I must have one!!
'09 kx450f 4-Poke
Gen-4 trail bike --SOLD--
Gen-3 badass trail/mx bike --SOLD--
Gen-1 built dunes bike --SOLD--
'05 klx110 --SOLD--
'95 pw80
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MICK
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Post by MICK »

So what was the final price then? Exactly what kind of benefit per dollar are we talking about...I think it looks terrific in the photos, sitting beside that carburetor you dug up from your yard makes it look even better :lol:

As I understand when you increase the bore of the carburetor you reduce the intake velocity at lower rpm. So wouldn't it make sense it would perform weak off the bottom with 39mm jetting? Or even after proper jetting has taken place? I'm not sharp shooting you, I'm just trying to better understand the benefits.

I'd really like to know how you think it runs now above half throttle! 2.5mm is a good size jump I think. Keep us informed as you become more familiar with it. You've got my interest for sure :D
'03 CR500 powered by...umm...a new motor?
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iggys-amsoil
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Post by iggys-amsoil »

With a hundred advantage, you'll be alright. :lol:
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sabreguy
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Post by sabreguy »

So what are you going to do with your old PWK? :wink:
88CR500
ROOST ON PEOPLE!!!
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AlisoBob
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Post by AlisoBob »

MICK wrote: 2.5mm is a good size jump I think. Keep us informed as you become more familiar with it. You've got my interest for sure :D
39.5 mm bore = 1224 square mm of flow area.

41.5 mm = 1351 square mm of area.... a gain of 127 square mm.

I think the price he has for the board is $220. This is about $60 off what most shops charge....

I like it so far.... I blasted up and down the street today.... felt stronger on top.... You know it was going to......new parts always feel faster.....

:wink:

I wouldnt buy it as a upgrade from a 39mm PWK ( even though I did).

It is a big step up from a PJ however...

I'll keep you posted on long term results...
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100hp honda
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Post by 100hp honda »

is this the same carb sudco advertises as the "41 proseries" ? i was going to buy one about year and a half ago but sudco didnt have any in stock. they told me on the phone the 41proseries was nothing more than a 39pwk that their local machine shop bores out. keihin is now sending out of the factory 41.5mm carbs ? :?:
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britincali
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Post by britincali »

sabreguy wrote:So what are you going to do with your old PWK? :wink:


I already got dibs on it :D
Coolness list by 90cr500guy

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Solidbro = cool
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sabreguy
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Post by sabreguy »

britincali wrote:
sabreguy wrote:So what are you going to do with your old PWK? :wink:


I already got dibs on it :D
DAMN!
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AlisoBob
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Post by AlisoBob »

:roll:

Brit dont have dibs on shit.....
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Slomo
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Post by Slomo »

AlisoBob wrote::roll:

Brit dont have dibs on shit.....
True dat... check yo PM's Bobbo :birthday:
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MojoScojo
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Post by MojoScojo »

I have a PWK 38 A/S I don't want...
No longer have a CR500.
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Get on with riding or get on with dying.
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Slomo
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Post by Slomo »

MojoScojo wrote:I have a PWK 38 A/S I don't want...
Gimme say.... 25 bucks and I'll take that piece of crap off your hands. Everybody knows those carbs only work good on mopeds.
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AlisoBob
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Post by AlisoBob »

Cracker is looking for a 38mm A/S....
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britincali
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Post by britincali »

AlisoBob wrote:Cracker is looking for a 38mm A/S....


Cracker need to start riding more, if you give him that carb it'll end up siezing together........
Coolness list by 90cr500guy

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LOVEMYCR500
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Post by LOVEMYCR500 »

I bored my 38 PJ to a 40mm and I think it feels the same as the 40.5-41.5 PWK with 55 pilot, DGK needle, 172 main. I have both carbs and can't really tell a difference. I have a local guy taper bore all my carbs 35-40.00. Same bottom end as the 38 (close) better mid to top end.
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