J
Jack Klarich
Guest
Harley Davidson Carburetor Performance Tuning Here is a good read with picture of the idle mixture screw location on a C V carb
Colas LeGrippa
Member
Hi everybody, bought my first Harley last october. A used Dyna 2002. I 've installed an E-Z mixture screw on the CV carb ( as stated in the article mentioned by Jack ) but has no effect at all either way I turn it. The engine is popping and farting but when the choke's on. So I guess the mixture is too lean. The jets are 45 and 195 and according to the test I've performed with a «quick start» fluid can, the intake is not leaking. I am now to the point considering drilling 1/8'' the vacuum hole near the needle jet, and/or putting washers under it, without knowing the effect or the result this may have. What would you suggest ? Thanks.
Colas
Montreal Canada
Colas
Montreal Canada
Colas LeGrippa
Member
Bike is idling perfectly, new fuel filter, fresh fuel. The engine starts at 1/4 turn with choke, after warming up idles perfectly. When I open the throttle,( choke not on ) starts to fart out. When driving, when stopped on red lights ( I do stop on red lights hey hey ), adjusting the mix screw has no effect at all. The bike has poor acceleration and max speed is 70 mph ( engine is 88ci ).
Colas LeGrippa
Member
slow jet is 45
Jet sizes should be fine, drilling the slide will only make it move quicker during acceleration it will shunt at other throttle openings looking for correct position
If it idles ok I would assume that the idle mixture screw is at a good position and the slow jet is a suitable size
If the problem is during acceleration then perhaps the accelerator pump is not providing sufficient fuel during acceleration
Remove the air cleaner and look in the carb snap the throttle open there should be a good squirt of fuel from the accelerator pump nozzle being directed straight down the throat of the carb
If bike idles ok will accelerate ok and starts to pop and backfire when you slow down and stop with engine cutting out at idle I would suspect icing of the slow jet
exact scenario of what is happening helps a lot with trouble shooting I assume that the carb has been stripped cleaned and the float height is correctly set as the jets can not deliver sufficient fuel if the float bowl is half empty
Brian
If it idles ok I would assume that the idle mixture screw is at a good position and the slow jet is a suitable size
If the problem is during acceleration then perhaps the accelerator pump is not providing sufficient fuel during acceleration
Remove the air cleaner and look in the carb snap the throttle open there should be a good squirt of fuel from the accelerator pump nozzle being directed straight down the throat of the carb
If bike idles ok will accelerate ok and starts to pop and backfire when you slow down and stop with engine cutting out at idle I would suspect icing of the slow jet
exact scenario of what is happening helps a lot with trouble shooting I assume that the carb has been stripped cleaned and the float height is correctly set as the jets can not deliver sufficient fuel if the float bowl is half empty
Brian
I agree with Brian, check the fuel pump. Check to make sure the squirt from the fuel pumps nozzle is directed straight down the throat of the carb. Could be the float is out of adjustment too. You should be able to close idle mixture screw off and make the bike stumble at some pont. If the carb. hasn't been torn down and rebuilt in awhile, it maybe a good time to do so.
Colas LeGrippa
Member
I have rebuilt the carb entirely. Accel. pump, diaphragm, very precise adjustment of the float according to HD specs. Before, the engine wouldn't start and fuel would come out from the air filter. Float out of adjustment would allow too much fuel in. I will try raising the needle by adding washers to enrichen the mixture. Spark plugs are desert sand dry which tells me that not enough fuel is getting in there.
Colas, Montreal.
Colas, Montreal.
