black smoke on accell popping on decell

K

knine08

Member
I just got the 08 k9 going and change the jets to what some have used on their 117 with vance hines 2 into1 and aftermarket air cleaner. I also have the booster venturi installed. stock cam

31 intermediate and 76 main stock air bleed.

have black smoke when on the throttle hard
have poping when letting off the gas slowing down

tried to turn down accell pump but it created stumble, so I turn it out until the stumble went away.

any thoughts where to start
 
S

Sven

Well-Known Member
knine08 said:
I just got the 08 k9 going and change the jets to what some have used
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'some have used' is not what yours might need. Have you run it without the jet change and how was it?


I also have the booster venturi installed.
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That's a rich variable right there. Yank it out and try a ride with the same jetting.
 
K

knine08

Member
I never ran it it before this. Had everything apart and added the exhaust and air cleaner. Thought I would install the jets I see people running for a starting point. I know I should have left it but was hoping to save a step. Oh we'll I will put stock back in and go from there. Seems odd it would pop on decell if I'm so rich on jetting
 
Tdubb

Tdubb

Active Member
knine08 said:
I never ran it it before this. Had everything apart and added the exhaust and air cleaner. Thought I would install the jets I see people running for a starting point. I know I should have left it but was hoping to save a step. Oh we'll I will put stock back in and go from there. Seems odd it would pop on decell if I'm so rich on jetting
Click to expand...
Many have popping on decel. In fact many who have v-twins have this issue, not just Big Dogs. It is more common on carb'd bikes because fuel is not as efficiently burned as EFI. So when you decel some air is pulled back into the chamber and unspent fuel will ignite. You can reduce this by making sure you don't have any exhaust leaks (particularly the crush gaskets - replace: cheap and easy). With your case you may be running rich and therefore have a bunch of unspent fuel just begging to ignite if some nice oxygen is supplied at decel.

Also black smoke definitely indicates rich. Popping on decel also may indicate that. Popping on accel or normal throttle indicates lean.
 
Srodden

Srodden

Well-Known Member
I've had decel pops with original pipes with baffles altered (drill hole size of quarter) on both 05 and 11 mastif 117 carbureted engines. I installed V&H 2 into 2 and removed baffles installed thunder monster baffles completely stop decel pop now have a nice decel growl. Baffle configuration on any engine changes everything good or bad.

S&S big inch engines do not like open pipes especially short open pipes.
 
DiscoBayJoe

DiscoBayJoe

Member
I've got the same symptoms. She pulls real good, but pops on decel and I get black smoke, especially when cold. 117 Motor, 585 Cam, V&H Big Radius pipes, no idea what jetting is in there.
 
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