Planet Minis

C_Thut · 02-16-2007, 04:42 PM

does anyone have any advice on how to tune a 72 carb? ive looked everywhere but all i can find is info on tuning other year carbs.

dirtbkr188 · 02-16-2007, 04:58 PM

Start with a baseline to return to. Jet needle clip in the 3rd (middle position, air screw adjusted out 1 1/2 to 1 3/4 turns, and clean tank of gas, and a good clean air filter.
Tuning a carb is not something that can be done in a few minutes, and then youre finished. You have to determine what the bike is doing (blubbering or gurgling, or is there some hesitation for a split second when you wick the throttle, is it backfiring on decelleration, etc. etc.). Then you make your adjustments to counteract the symptoms. You have to determine whether or not it is running too rich, or too lean, then you have to determine why it is doing what it is doing. Trying to fine-tune a carb on a 25 degree day is a lot different than if it was 70 degrees outside.
As far as the specific settings for your '72, that could vary as much as the weather temperature. Establishing the baseline to work from, and return to, is, to me, the best way to dial in your carb. You have to dedicate a serious amount of time and effort to do it correctly.

02-16-2007, 04:42 PM	#1 (permalink)
C_Thut 2nd Gear Member Join Date: Jun 2006 Location: morris/wolcott CT Posts: 322	carb tuning :( blah! does anyone have any advice on how to tune a 72 carb? ive looked everywhere but all i can find is info on tuning other year carbs.

02-16-2007, 04:58 PM	#2 (permalink)
dirtbkr188 3rd Gear Member Join Date: May 2004 Location: New Jersey Posts: 2,972	Start with a baseline to return to. Jet needle clip in the 3rd (middle position, air screw adjusted out 1 1/2 to 1 3/4 turns, and clean tank of gas, and a good clean air filter. Tuning a carb is not something that can be done in a few minutes, and then youre finished. You have to determine what the bike is doing (blubbering or gurgling, or is there some hesitation for a split second when you wick the throttle, is it backfiring on decelleration, etc. etc.). Then you make your adjustments to counteract the symptoms. You have to determine whether or not it is running too rich, or too lean, then you have to determine why it is doing what it is doing. Trying to fine-tune a carb on a 25 degree day is a lot different than if it was 70 degrees outside. As far as the specific settings for your '72, that could vary as much as the weather temperature. Establishing the baseline to work from, and return to, is, to me, the best way to dial in your carb. You have to dedicate a serious amount of time and effort to do it correctly.

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