PD46A Rejetting With Velocity Stacks

CarbonK

CarbonK

New Member
I have a 1977 CB550K and I'm working on removing the side covers and getting that open look under the seat. I decided to go with velocity stacks instead of the stock airbox or pods. Anyone have any recommendations or a good starting point into what size jets I should be using, needle position, and mixture screw turns for PD46A carbs with stacks and a Mac 4 into 1 exhaust? If anyone with the same setup can chime in it would be much appreciated.
 
No help on jetting, but be sure to use some kind of fender between your back tire and the stacks, otherwise you're sucking dust, dirt, grime, water, and rocks into your motor. With stacks that will likely happen anyways if you're not relegated to a race track, but if you're dead set on using them at least be smart about it.
 
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unless someone has specific info, i would warm the bike up then ride it for just 2 minutes . . if it burbles, go down on the main two sizes . . if it does not, i would go up 3 sizes on the main . . if it still does not burble, go up 2 sizes at a time until it does . . once you reach this point, jetting is much easier . . simply go down 1 size at a time until it stops burbling then go down one more.

once the mid to top end is jetted you can deal with the low speed jet and needle.

if you ride it for m ore than two minutes while it is lean, you might discolor your pipes sat the head if they are chrome.
 
coyote13 said:
No help on jetting, but be sure to use some kind of fender between your back tire and the stacks, otherwise you're sucking dust, dirt, grime, water, and rocks into your motor. With stacks that will likely happen anyways if you're not relegated to a race track, but if you're dead set on using them at least be smart about it.
Click to expand...

Thanks for the forewarning, I'll be cautious.

barnett468 said:
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unless someone has specific info, i would warm the bike up then ride it for just 2 minutes . . if it burbles, go down on the main two sizes . . if it does not, i would go up 3 sizes on the main . . if it still does not burble, go up 2 sizes at a time until it does . . once you reach this point, jetting is much easier . . simply go down 1 size at a time until it stops burbling then go down one more.

once the mid to top end is jetted you can deal with the low speed jet and needle.

if you ride it for m ore than two minutes while it is lean, you might discolor your pipes sat the head if they are chrome.
Click to expand...

Sounds like good advice, I'll try this out. Thanks.
 
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xlnt . . let's get er done!

you can also buy wire mesh screens for the stacks to stop the big pieces anyway, lol.
 
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