Carb jetting advise

Guys im still getting a very slight stumble at take off . It gets better as the bike warms but the plugs are black so i know its rich.
When i got the bike it had a lean condition (craking popping ect)
Now it runs beautiful at all ranges EXECPT start off.
I can pull the choke lever and it fires immediately and i can get off the choke pretty quick.
So Im running the 28mm pumpers and I know the sprays are spraying well.
17.5 pilots 117.5 mains stock air box Delvick header.
Air mixture screws about 3/4 out. thats the best i can get em if I come out anymore the stumble gets worse.
Idles great just that first little smidge when taking off it will stumble slightly.
Any thoughts from yall? Yes the valves are adjusted properly and the floats have been set using the clear tube method.

thanks for the help guys

CV carbs, air box etc?
Steve

stock air box VM28mm pumper carbs. Delvic header
I think ive about decided my pilots are too big so Im gonna pull the carbs in a couple of days when im off and go down to a 15
at least that will answer that question.. I dont feel like i should have the air screws so far in. But thats where I get the lest stumble.

strum wrote: Guys im still getting a very slight stumble at take off . It gets better as the bike warms but the plugs are black so i know its rich.
When i got the bike it had a lean condition (craking popping ect)
Now it runs beautiful at all ranges EXECPT start off.
I can pull the choke lever and it fires immediately and i can get off the choke pretty quick.
So Im running the 28mm pumpers and I know the sprays are spraying well.
17.5 pilots 117.5 mains stock air box Delvick header.
Air mixture screws about 3/4 out. thats the best i can get em if I come out anymore the stumble gets worse.
Idles great just that first little smidge when taking off it will stumble slightly.
Any thoughts from yall? Yes the valves are adjusted properly and the floats have been set using the clear tube method.

Mains are to big.
Idle screws should be 1 1/4 out.
Stock cams? If so go back to 15s.


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thanks nebr_rex
I have some 115 mains . should i try them and the 15 pilots?

One change at a time.


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Nebr_Rex wrote: One change at a time.


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Crap i knew you were gonna say that :laugh:
Ok Ill put the 15 pilots in and go from there.

I ride 100 miles after a change to let things settle in, then move on if needed.
Steve

swest wrote: I ride 100 miles after a change to let things settle in, then move on if needed.
Steve

I agree i thought it was good as the plug color looked good to me after a short ride but after more riding they look black.. I think this gas dont turn the color as quick as it used too.
I did some WOT up hill tests and I dont get any indication that the mains are wrong .
If I go WOT then back off to 3/4 i have no speed up or stumble so thats what im looking for and all the mid range is good .

I've set carbs rich only to have them lean out in time. If they're too rich, they'll wash out the rings and you'll lose compression, then dark plugs etc.
Steve

If you haven't done so also check your advance timing unit.