from what I have researched it seems that the jets are "too big" if the adjuster is less than 1.5 turns out and too small if it is 3.5 turns out. What is the significance of this? I am running stage 1 s.e. airfilter and Rush slipons and have a 48 low and 200 main jet. I get best results at about 1.5 turns out. Why would my jets be say too big vs. say a 46 /195 and 2.5 turns out. If the mixture is adjusted right what is the difference or logic for the above recommendations.

 

Not sure what kind of Carb you have.

For example a Mikuni HSR series the air screw should be more than one turn out, and not more than 2.5. If it is less than one turn out your pilot jet is too small. More than 2.5 and your pilot is too big. None of this has anything to do with your Main Jet. The air screw is strictly for adjusting the pilot circuit.

 

got the stock CV . I understand the "rules" but do not understand why they apply. Just an old wives tale or is there an actual sound reason why if my fuel air is adjusted "only" 1.5 turns out the jet size is too small.

 

The CV carb and the Mikuni work two different ways on the Idle circuits but if you use a little logic you can figure it out.

on the Idle circuit on the Mikuni, the Idle screw adjusts air. and the pilot jet meters a certian amount of fuel. If you have the screw less than one turn it, and it idles fine the circuit is considered lean. This is because your pilot jet is letting X amount of fuel in the carb and at less than one turn out the small amout of air that is getting in is making a proper A/F to run the engine, but probably not enough to keep it running cool as it warms up and cold starts will probably stink.

On the CV the screws is in the in the rear, and adjust a fuel circuit. and it works just the oppisite.

 

ok so I am in essence restrictiing the amount of fuel by running the bike at 1 5/8 out. So i may be better at 3 or so turns out with the stock jets if my bike will not be in lean condition? I'll tinker tomorrow and see.

 

I have an '04 Night Train with stock carb, Vance and Hines Pro-Pipe with street baffle and Screamin' Eagle air cleaner. I put the Thunder Slide kit in mine and went up to the 45 slow jet and 195 main jet and put the clip on the 5th groove down and not the 4th. Mine seems to want the screw at about 3 to 3.25 turns out...FYI
p.s. the thunderslide kit has a different slide (plastic) and needle.
Scott

 

A 48 jet is rich for your bike unless your intake is leaking. I have learned the hard way that before making any changes to jetting, check your intake for leaks. HD's design is notorious for leaks so save yourself some headaches and check it first. Most people put too large of a slow speed jet trying to compensate for a lean cough. This cough is caused by the needle to needle jet relationship. At slow speeds your needle is still all the way down and before it starts to rise it is allowing some fuel to get by the straight part of the needle. The problem is there is not enough fuel coming out and causes a lean condition. A 1988 1200 sportster needle is .002" smaller on this straight section and will stop the cough. Your mileage should be at least 45 mpg. If not that will tell you your too rich. It's easy to throw fuel at a Harley and make it run fast but it takes some patience to dial it in to make it run right. The old rule of thumb, as mentioned above, is for the Mikuni. My CV is 2.5 to 3 turns out. Good luck!

 

the bike seems better with the stock low jet and 200 main jet. I do not get a cough at even 2 1/8 turns out. the plugs show rust and off white coloration. Starts good as long as I gas it when warm like the service manual recommends. The 48 was way too rich for the bike it started to foul the plugs when I had to run the enrichener more for the cold weather we had here in Fla. The 200 may seem large but I feel it may go with these rush pipes I have as the bike just pulls strong instead of flattening out like it did with the stock 190.
Passes the test for main jet size posted by HD TECH. in his help forum. The pipes are really loud with the bike leaned out more. I like it! I did nothing the needle.