I just purchased a 2000 Heritage Softail Classic with a 95 inch big bore kit. After riding the bike a little bit the engine RPM goes up significantly. What is the proper way to adjust the idle RPM?

I want it to have that nice lope but I don't want to be so low that the engine is not getting enough oil. I hear that if you ride the bike until its a operating temp. you the turn the idle down until the bike stalls and then turn it up until the bike runs with out stalling.

Is that correct or do I need to take it to a dealer?

Thanks.

 

Do you need to use the choke to start the bike? If you are able to start the bike withut the choke, or take it off choke almost immediately withut stumble your idle mixture is too rich. Too rich an idle mixture will reveal itself sometimes as a high idle at operating temp.

Assuming you don't have access to an exhaust gas analyzer, I like to set idle mixture as follows: get emgine to operating temp. Adjust idle at throttle screw to correct level. Turn idle mixture screw in until the engine stumbles. Turn it out until it runs smothest (highest idle). Readjust idle at throttle screw.

 

Nice response! You also might want to pull your plugs and see how the burn is. Plugs should be a tan color. If they are black, you know the air/fuel mixture is too rich. In addition, you might want to check your jets to see what you have in the carb.

 

Thanks for the response and I know this is a dumb question but I still don't understand what the correct idle level is? Any way to do this with out going to the dealer?

 

I don't have a service manual but I'd say 1000 RPM + or - 50 RPM is going to be good. Your bike doesn't have a tach so you'll have to do it by ear if you don't have a remote tach. A little too fast is a lot better than a little too slow. In the drawing below, part #150 is the idle adjustment,

 

Working on my bike, my son broke the plastic 90 degree turn on my carb. It is part #288 on the diagram. What is the name of this part. I want to order one, but need a part number or name to do so.

 

http://partsfinder.onlinemicrofiche....RETOR-ASSEMBLY

Plug in year and make and then go to the carb display.

27371-76 FITTING

 

Unless you've got a huge cam in it, the bike is not going to "lope" like people think it should. If it's loping, then the idle is too low. It's not a shovel head or single cylinder. Like the other poster said, set it at 1000, since it is carbed it is going to vary depending on weather. When it's cold out, or my bike is below around 150 degrees oil temp, it will only idle at 950. When the bike is at normal operating temp of 180-190, it idles at 1000, and if it gets hot (around 195-200), then it'll jump up to around 1100 or 1150 idle at times. 950 RPM will give you that "lope" you're talking about without sounding like it is laboring to keep the motor spinning. If you're hearing that when the bike is hot then idling is set too low. So, by ear, if you think it's too high, crank it down to that sound when it's hot, then turn it back up to the point where it idles at a steady sound. Depending on your set up, the front wheel, handle bars, something, should vibrate at a steady pace if the idle is correct. Idling too low results in the top end not being oiled properly, and causes delay in response off of idle.

Depending on how the accelerator pump is set (something people usually neglect) it can mask the delay off of idle, but still cost you performance. Whatever carb you are running should be jetted with the accelerator pump set to be inoperable, the accelerator pump is only to make up for off idle response when you quickly snap the throttle (makes up for a lag between the slow and mid circuit or slow and main circuit depending on the carb). The andrews accelerator pump is overkill and won't work properly with all circuits unless you have some means of adjusting it. The fact that harley did away with the adjustment for the accelerator pump on late model butterfly carbs and also on cv carbs is, in my opinion, what causes headaches for people when jetting and creating a smooth running bike through all of the rpm range.