I have a 97 sporty 1200 custom,11,000 miles. straight pipes, stock air cleaner with lots of extra holes drilled in back.New seals at carb and manifold. Rejetted to #48, and turned out mixture screw 2 1/2 turns. Runs pretty good. not real quick responsive,stalls sometimes at a stop. and the plugs NGK D7EA are sooted black with the front plug ceramic clean white. where do I go from here?
Carb jetting Qs
- Thread starter poolguy
- Start date
Main jet? Any washers under the needle? Did you adjust your idle-air mixture screw to optimize it or just turn it out the 2 1/2 turns? Accelerator pump cleaned out and the diaphram checked?
Great stuff here:
Fuel and Carb Related Issues - Harley Davidson Community
TQ
Great stuff here:
Fuel and Carb Related Issues - Harley Davidson Community
TQ
The 48 for a slow jet is perhaps a wee bit too much a 45 would be my choice plug being black and sooty the best way to check plug colour is to do a plug chop bike should be pulling hard pull clutch and kill engine at the same time coast to the side of the road and check the plugs
However modern fuels may not show on plugs in the same way as the older fuels did
Doing a plug chop will only show how things are during main jet operation if it is still looking rich then perhaps the slow jet is still too big as it delivers fuel all the time
check operation of the accelerator jet by removing the air cleaner look in the throat of the carb and snap the throttle open you should see a squirt of fuel being directed down the centre of the throat of the carb
Brian
However modern fuels may not show on plugs in the same way as the older fuels did
Doing a plug chop will only show how things are during main jet operation if it is still looking rich then perhaps the slow jet is still too big as it delivers fuel all the time
check operation of the accelerator jet by removing the air cleaner look in the throat of the carb and snap the throttle open you should see a squirt of fuel being directed down the centre of the throat of the carb
Brian
A very important part of the idle mixture adjustment process is to be sure your idle rpm is set correctly. The reason is that you can actually render the slow jet useless if the idle is set to high. If you can close the idle mixture screw to lightly seated with your idle rpm's set correctly. Your slow jet is too big and needs to be decreased.
Your second second tells the tale. That slow jet is too big. Try a 45 and possibly 46 if you have a real high flow air system. You should NOT be able to turn the mixture screw in all the way without doggin' and even stalling the engine. You might also put a couple of #4 SS washers on the needle.
TQ