carby

[david lee]

took the shovel for a ride today in traffic conditions and and after around 3miles it started misfiring as if it was running out of fuel. got it home took the plugs out and they are black which tells me its running rich. am i correct .its a s&s-b. the main jet is 072 and intermediate is  0295. any thoughts would be helpful. thanks

[JW113]

Correct, black = rich.

When is the last time you looked at the plugs? When is the last time you rode the bike? When is the last time you took it out on the highway and nailed it WFO up to the redline (i.e an Italian tune up)?

-JW

[david lee]

ridden 4-5 mths ago no problems do you know the stock size int jet the jets were changed at 1 stage for the same reason its trial and error thanks

[hbkeith]

if it ran well before , i would not change jets , points move ?

[kd]

Float level? It can effect all ranges.

[rigidthumper]

Enricher plunger left slightly up will blacken plugs rapidly.

[guppymech]

Super B Jetting Chart.  My engine with a Super E likes the leaner end of the range.

[JW113]

This sounds like the school of thought of "I changed something so I need bigger jets".

-JW

[Burnout]

Idle mix screw on a S&S carb is very sensitive, 1/8 turn is a significant change.

You MUST tune the idle mix on a fully warmed up motor.

If you set the idle mix on a cold motor, it will blacken plugs.

The idle circuit supplies a significant amount of the light throttle fuel.

[thumpr54]

"Enricher plunger left slightly up will blacken plugs rapidly."

my vote....esp if it runs better next time out....one time hiccup....

[david lee]

Float level? It can effect all ranges.

float level good. this carby originally came off a non stock bike motor

[Ohio HD]

I assume a stock 74"? I would suggest looking at 0.068 or 0.070 main jet. Open exhaust you might need the 0.070. Also a Super 'B' is too large for a stock 74" if that's what you'e running.

[bump]

I have a S&S B with 68 main and 29.5 mid. If you forget to close enrichener it will foul plug. Turns Turns plugs black black pretty quick. Been funning it this way for 35 years.

[Lowrider!]

I'm running .033 intermediate and .072 main on a 1978 74 c.i. FXS with KB 9.5-1 pistons, Crane 300H cam, staggered duals, mid to high 40's mpg.

[david lee]

this carb came off a non stock 1340 and when i bolted it on was running rich. my hd mech changed the jets , guess work and said try this the plugs have always been black since but not misfiring until the latest ride. the enricher is off and float level good. my mate cleaned the plugs and said go for another ride and see what happens  but im sure nothing will change

[bump]

Pull the enrichener out of carb and check the orings. I had to replace the oring at bottom of enrichener after about 25 years of carb on bike. Also check that throttle plate and shaft are not worn.

[david lee]

Pull the enrichener out of carb and check the orings. I had to replace the oring at bottom of enrichener after about 25 years of carb on bike. Also check that throttle plate and shaft are not worn.

will do

[Hossamania]

Also sounds like you're ready for an E carb...

[76shuvlinoff]

Also sounds like you're ready for an E carb...

  Stockish bike or even mildly modified?  I'd opt for a CV40 with a solid press-on adapter and not look back.

[attach=0,msg1383963]

[Ohio HD]

  Stockish bike or even mildly modified?  I'd opt for a CV40 with a solid press-on adapter and not look back.

[attach=0,msg1383963]

   

[david lee]

took the carb to my hd mech checked it out. all is good he put in a 0.80 int jet. he said a 0.265 would run to lean

[kd]

 

[david lee]

0.280

[JW113]

Dave, this is a discussion like oil. Everybody has their opinion, and they all suck. However, Super B is 70's technology targeted to drag racing. If you want to apply that to a street bike, well then good luck. There are alternatives that are much more street friendly, for example the CV-40. I have one on my Shovelhead, and it works flawlessly. HD evidently thought so also. S&S carbs are fine, but are more drag race oriented. Is that how you ride? If not, then consider a more street manners friendly carburetor.

Just sayin'...


-JW

[david lee]

Dave, this is a discussion like oil. Everybody has their opinion, and they all suck. However, Super B is 70's technology targeted to drag racing. If you want to apply that to a street bike, well then good luck. There are alternatives that are much more street friendly, for example the CV-40. I have one on my Shovelhead, and it works flawlessly. HD evidently thought so also. S&S carbs are fine, but are more drag race oriented. Is that how you ride? If not, then consider a more street manners friendly carburetor.

Just sayin'...


-JW

got it