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· Registered
13 Posts
Discussion Starter · #1 ·
Hi all,

I am a fairly new to owning a Harley. I got it earlier this spring. I have an 81 shovel (80in all stock motor) and have had various problems that I have managed to fix myself. I now have a problem that is eluding me.

Over the past month or so I start the bike up it runs and idles fine. It seems that after the motor gets hot the idle just keeps climbing. The idle set screw is all but completely backed out right now. If I am sitting at a light and push in on the throttle linkage then it will idle down, but as soon as I let off it comes right back up. At first I was thinking a weak return spring, but the fact that it works fine when cold and that it goes back to a really high idle when I let off of pushing the linkage makes me think not so.

Should I just pull the carb off and do a rebuild of it or is there something I am missing that is very easy.

This happened once before but it was also doing it while cold. Turns out that time was due to my choke being pulled out enough to make it run on high idle. Something else is going on this time.

Any help would be appreciated. Sitting at a light and idleing at 2000+ rpm is REALLY annoying.



· Registered
336 Posts
Hi there,
Probably you guys have a maladjusted "idle mixture "
Any carb has got this "idle mixture screw".
Basically the adjustment at any carb is like this (provided ignition,
valve-adjustment,jet-sizes and float in carb ok;
slack in throttle cable needed.
Improper fixed carb-manifold clamps is another common cause for irratic speed,
blocked air-filterelement as well.

Engine needs to be hot
Start it
No choke
-turn the "idle speed screw" in ,so the engine keeps running
-turn the "idle mixture screw" in till the engine-speed picks up (mixture
becomes too lean)
-rev it up ,just a short burst
-turn the "idle mixture screw" out till the engine almost dogs out (mixture
becomes too rich)
-rev it up
-reduce (turning out) or increase (turning in) the idling-speed with the
"idle screw"
-rev it up
-repeat the "idle mixture screw adjustment" untill the bike picks up speed -nicely and running ok in idle-speed.
-the proper idle mixture setting is about half-way between the "too-rich" and
too "too lean" settings
-Keep in mind that a cold engine is slower than a hot
-Don`t forget that a really hot Shovel will boil the fuel in the
fuel-lines and carb meaning; Ride the bike, so that it can cool down a
-Testrun the bike over a some miles (not just a few), keep a
screwdriver in your pocket and adjustit till alright.
-When you believe, everything is alright,ride the over some distance, say
40mls (no city-traffic !).
-Turn out the spark-plugs and have a look at them but that`s another topic

Common back and tell us about your experiences


· Registered
13 Posts
Discussion Starter · #4 ·
Hey thanks for the info..

I think you hit it with the manifold clamps. The carb seems to be somewhat loose, I noticed this when I was putting the air filter cover back on that it moved up and down. If I pulled it up toward the tank it idles fine, if it falls down away from the tank it goes high. I'm assuming that is because the throttle has tension on it at that time.

Thanks also for the tuning tip cause I probably threw it out of whack while I was messing with it yesterday.

I hope to be able to go home after work today and get that issue solved, I'll let you know how it went.

Thanks Again

· Registered
13 Posts
Discussion Starter · #6 ·
no.. it doesn't.

I need to go get or make one it sounds like. Not that it matters much right now. My clutch cable broke the night I figured all that other stuff with the idle. Not that this is a major problem but the piece that you slip teh barrel on one end of the cable fell out of the hand lever. At least I'm on vacation next week so I can have more time to mess with it then.
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