Got a 1994 sportster with new plugs. Runs great idles great until u get to 3000 rpm or more say half throttle and starts cutting out really bad. You can pull in clutch and revs up fine. drop below half throttle and runs perfect. Don't know what's wrong I checked plug wires and coil wires and all battery cables and everything looks fine. Please help I miss my sporty!

 

Sounds like a fuel related issue. Others will chime in also.

 

How many years has it been since the carb was rebuilt?
How many miles on the bike?
Did the problem just start suddenly?
Is the bike ridden regularly?

 

Sounds like a partially clogged mainjet. Pull the carb, check the float bowl for boogers, clear your mainjet and pilot while your there. Make a note of your jet sizes for future reference if you plan any performance mods.

John

 

When u say cuts out at half throttle are you at a stand still or riding?

 

Take a look at my post from last year mine turned out to be jetted to lean.
https://www.hdforums.com/forum/sport...g-problem.html
HTH
Barry In MO.

 

also check the screen on the tank end of the fuel petcock....it sounds to me as if it is starving for fuel....so check everything from tank to where the fuel is sucked into the carb venturi...oftenly one of the symptoms is that the bike will rev up fine sitting still out of gear, but when you are driving the motor will only accelerate up to a certain RPMs....

 

Its a 1994 1200 with 23,000 miles. Problem just started out of nowhere and have been riding it weekly or more for the past year. I had the carb tuned and jetted and has ran perfect for the past year.it doesent cut out sitting still only when riding and u start to get in it hard. Any info is appreciated. Thanks guys

 

Just pulled petcock and replaced the fuel line .. same problem stii I am stumped

 

I would pull the carb. take all 3 jets out (that includes the one for the float needle) and blow all the ports out ..take a real good look at the port for the float needle and make sure there is no crap in it....next put the float in a cup of water and see how high it floats and then hold it under the water and see if any bubbles come out, if it bubbles or doesn't float like it should replace it...maybe replace it anyway, they are not that expensive...when you reinstall it make sure and it to the right height and make sure it is not bent to either side where it might rub the float bowl....the problem you are having is classic fuel starvation, caused by not enough fuel flowing through the carb...the cure is to make sure there are no restrictions in the fuel passages (petcock, line and ports) and the the float height is correct, if the float level is too low when you get on the motor hard there is not enough reserve fuel in the float bowl to keep up with the demands of the engine (the engine can burn the fuel faster under load than the fuel line to the carb can supply the engine, and that is the main reason they use a float bowl)....the only other thing that I would check and I am not sure your bike even has one is the diaphragm cut valve by the petcock....