Author Topic: carb jetting help  (Read 682 times)

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joe750

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carb jetting help
« on: September 26, 2012, 09:45:48 PM »
Ok heres the skinny...
Im running the cycle x 2-1 intakes on my 76K bobber with 2 mikuni 34mm round slide carbs.
Running pods and straight pipe exhaust that barely make it to the foot pegs
190 main jet and 35 pilot jet

Runs like a scalded dog above half throttle

From 1/4 - 1/2 throttle, its a different story.
Its got a flat spot in between these throttle positions

Should i go up in the pilot jet size?
Air screw is 1-1/4 turns out.
I could turn it back some but wouldnt that effect the way it runs above 1/2 throttle too?

Offline fdbrat

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Re: carb jetting help
« Reply #1 on: October 06, 2014, 07:17:23 PM »
Bump.
1975 CB750F
4-4, Dyna S and box
5 ohm coils / 5k ohm caps
In- .05 / Ex- .08

San Luis Obispo

Offline evanphi

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Re: carb jetting help
« Reply #2 on: October 07, 2014, 06:02:34 AM »
The midrange will suffer with such short open pipes. They're designed to be running at WOT.
--Evan

1975 CB750K "Rhonda"
Delkevic Stainless 4-1 Header, Cone Engineering 18" Quiet Core Reverse Cone, K&N Filter in Drilled Airbox
K5 Crankcase/Frame, K4 Head and Cylinders, K1 Carbs (42;120;1 Turn)

She's a mix-matched (former) basket case, but she's mine.

CB750 Shop Manual (all years), searchable text PDF
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Offline flybox1

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Re: carb jetting help
« Reply #3 on: October 07, 2014, 06:54:32 AM »
have you done a plug chop for mid and idle throttle positions to determine for yourself if its lean or rich?
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

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