Jetting Questions??

BadBoy

BadBoy

Member
Gents,

2009, K9...117 S&S...stock carb, K&N air cleaner, V&H-2 into 1 BR pipe. I have read in the tech forum that jetting for this pipe and cleaner should be set with main jet of .078 and intermediate at .031 Does anyone have any thoughts regarding this jetting config or any other carb settings I should be aware of with this new set up for the intake and exhaust?? Help is greatly appreciated!!
 
V

V

Guru
BadBoy said:
Gents,

2009, K9...117 S&S...stock carb, K&N air cleaner, V&H-2 into 1 BR pipe. I have read in the tech forum that jetting for this pipe and cleaner should be set with main jet of .078 and intermediate at .031 Does anyone have any thoughts regarding this jetting config or any other carb settings I should be aware of with this new set up for the intake and exhaust?? Help is greatly appreciated!!
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You should be close. Might check your plugs after ride to see how they look. also as noted above might want ot read the jetting instructions from S&S. Stay away from the enrichener at start up as much as you can as it can foul the plugs and give you a false reading if you look at them for jetting purposes
 
BadBoy

BadBoy

Member
Thanks gents....I am assuming trial and error with main jet and intermediate jet based on plug indications and overall sound and performance.
 
Raywood

Raywood

The Pirate
Staff member
Calendar Participant
Troop Supporter
The V&H BR pipes come from the factory with a 31/76 combo.

:cheers:
 
Exotic

Exotic

Member
I am tuning mine as well and have a 117, Big Rad pipes, and open spike type air cleaner. Stock motor otherwise. Only use the enrichener to start then turn it off and use the throttle to warm her up.

31/76 - lean white plugs, sneezinig through carb.

32/78 - ran better, some hesitation and sneezing but rich black plugs.

31/78 - runs great to about 3,000 rpm then leans out with sneezing through the carb. Plugs are nice and toasty brown after riding at 2 to 2,500 rpm.

I am going with a 31/80 tomorrow and see how that does on throttle at 3 to 3500 rpm. If all runs well I will check the plugs for a reading after a ride in that rpm band and immediate shut off.
 
T.Byrd

T.Byrd

Well-Known Member
Exotic you might try pulling the vent plug to see if this helps. Lots of people running spike style intakes have to pull plug. I've had mine out for ever.
 
G

Gas Man

Cool isn't cheap
Calendar Participant
Exotic... never change 2 jets at once... cause you don't know which one did what.

Go with 32/76. The black plugs are probably coming from the main jet being too rich.

Please try this before screwin with the vent plug

Also, did you re-adjust the carb after each jet change?

Did you try to run each jet seperately when checking them as I said in the tuning how to thread?
 
Exotic

Exotic

Member
Gas Man said:
Exotic... never change 2 jets at once... cause you don't know which one did what.

Go with 32/76. The black plugs are probably coming from the main jet being too rich.

Please try this before screwin with the vent plug

Also, did you re-adjust the carb after each jet change?

Did you try to run each jet seperately when checking them as I said in the tuning how to thread?
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I won't change both again. I pulled the bowl off, hoping to only do it once so take a big swing at it.

Yes, re-adjusted mixture and pump each time. And yes, ran as you stated in the thread, cut her off and coasted, pulled the plug. There aren't any shortcuts even though I hoped to find one changing both at once. :bang:

I will give the 32/76 a shot and see what it does. I always ride at 2500 and below rpm... rarely hit 3K and up. I say that because I wonder how much influence a 78 jet has on the engine even though the rpm is less than where it should matter. Since there is no special "switch" that occurs, and the speed of the airflow (vacuum) pulls fuel from the bowl then it would stand to reason that a larger main jet would influence the AFR to a point even though the rpm are below the 3K speed.

What would pulling the vent plug accomplish?
 
T.Byrd

T.Byrd

Well-Known Member
Chris, I've got a 31 inter. and a 78 main in mine and im running my acc. pump about 4 turns out do you think I should go up to a 32 inter. It runns pretty good most of the time but it does hicup every once in a while.
 
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Exotic

Exotic

Member
T.Byrd said:
Chris, I've got a 31 inter. and a 78 main in mine and im running my acc. pump about 4 turns out do you think I should go up to a 32 inter. It runns pretty good most of the time but it does hicup every once in a while.
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Where in the RPM band does it hickup? 4 turns out is a bit much, and does it hickup when you are crusing or accelerating?
 
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LDO

LDO

The Cleaner
Troop Supporter
T.Byrd said:
Chris, I've got a 31 inter. and a 78 main in mine and im running my acc. pump about 4 turns out do you think I should go up to a 32 inter. It runns pretty good most of the time but it does hicup every once in a while.
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Dang,
S&S tunning states you should be about 2 turns out on the acc pump (give or take).
 
Exotic

Exotic

Member
Exotic said:
I am tuning mine as well and have a 117, Big Rad pipes, and open spike type air cleaner. Stock motor otherwise. Only use the enrichener to start then turn it off and use the throttle to warm her up.

31/76 - lean white plugs, sneezinig through carb.

32/78 - ran better, some hesitation and sneezing but rich black plugs.

31/78 - runs great to about 3,000 rpm then leans out with sneezing through the carb. Plugs are nice and toasty brown after riding at 2 to 2,500 rpm.

I am going with a 31/80 tomorrow and see how that does on throttle at 3 to 3500 rpm. If all runs well I will check the plugs for a reading after a ride in that rpm band and immediate shut off.
Click to expand...
32/76 fat down low black plugs, overall not good.

31/80 toast brown again and good pull up high... still have a stumble under hard acceleration... but I don't think I have the pump set right yet. I am at 2.5 turns now - still testing.

T - I agree up one on the int.
 
G

Gas Man

Cool isn't cheap
Calendar Participant
Yeah T... I think alhall said his dyno guy also said... much over 2 turns out consider going up a int.

Exoic... its got to be that damn spike... I know Doug G just had some problems with his and he's got one...
 
T.Byrd

T.Byrd

Well-Known Member
Changed my inter. jet today from a 31 to a 32 and reset carb. it took the dead spot between the inter. and main plum out and reset the acc. pump back to 2 turns out it has never been so responsive. Thanks all:
 
Chopper Dave

Chopper Dave

SIICK!!!
T.Byrd said:
Changed my inter. jet today from a 31 to a 32 and reset carb. it took the dead spot between the inter. and main plum out and reset the acc. pump back to 2 turns out it has never been so responsive. Thanks all:
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cool shit!:up: glad to hear you got it straightened out!:whoop: :cheers:
 
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