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Red-Doggy
07-22-2005, 03:30 PM
lately I was talking to a biker friend about problems on my '77 FLH. I told him I couldn't seem to find & hold a good idle speed. It always seems too fast, and when i slow it down it usuaaly stalls at a stop light. Also, it doesn't take long for the plugs to foul - they look like charcoal after 100 miles. he asked about my carb, I told him its an S&S Super G. he says the G is way too big for an 80" shovel, said I need a Super E. any ideas?

SchimDog
07-22-2005, 03:49 PM
You are running rich. Whether that be because of the carb being to big or that it is just not jetted right, some of the experts here will have to answer.

Have you tried going down a size on the slow jet?

junior
07-22-2005, 03:49 PM
you can jet a g to work on a shovel (yours likely needs that) but in general, a g is too much carb and even jetted right has poor low end performance....

try an e, or better yet a b or an s/u....

j

rwpatton
07-22-2005, 03:58 PM
I would agree with your friend.

The 2 1/16 diameter carb throat is to large for a basically stock 80" motor. Idle problem and low speed stumble is cause by too slow air intake velocity due to the large diameter. Smaller carb will cure this problem. Fouling the plugs is probably because it is jetted to rich.

Hope this helps.

RW

Stoney
07-22-2005, 04:00 PM
That G is specifically designed for BIG inch motors. Its way too much for a stock bore & stroke motor. bottomsup

SchimDog
07-22-2005, 04:02 PM
See... junior's and rwpatton's replies are alot better and more tech than mine!!!!!!!!!!! :D :D

Heretic
07-23-2005, 04:51 AM
rwpatton is correct, and for exactly the right reason. Air moves through the carb venturi as a fluid, speeding up as the throat reduces in size. this added velosity causes the low pressure(vacuum) to draw the gas up through the carb jet from the bowl. If this velosity is too slow (read as the throat is too big to create needed velosity) this low pressure is not achieved, and you get a lean condition, even thouh the carb is too big. Here is where most people make mistakes, they go with a larger jet trying cure this. The fatter jets will help keep you from burning the engine up, but you will have the same problems that you are describing

rwpatton
07-24-2005, 02:00 AM
Well said Heretic. Alot better description then how I described it. Cool.

RW

Red-Doggy
07-25-2005, 05:08 PM
Thanks for the help. So I can pick up a Super E thru J&P. Any idea what would be the best size jet for an 80" shovel? It has 2 sets of plugs on each cylinder, if that makes a difference.

Heretic
07-25-2005, 08:19 PM
When you get the carb, it will have a "jet guide" that will be the factory recomendations. They are a good starting place. Anything I could tell you now would just be a guess, because I do not know what is installed in your engine or how it runs. I can tell you that dual plug shovels like to run a litle rich. The best advice I can give is to disadle the accelerator pump while tuning the carb. Then enable, and adjust the pump. this removes the confusion of lean jeting vs fat pump.