Engine Idle - Random fluctuation

[2Flights]

After synchronizing the carb’s within 10 mmHg (each column) using the Carbtune Pro (at an idle between 1,000 – 1,100 RPM) on a 2006 RSTD the engine idle then randomly fluctuates between 730 and 1750 RPM’s. Obviously, when this change in idle speed occurs the previous adjustment (in vacuum) to match all columns exceeds 10mmHg. You can adjust the idle adjust screw to change the engine idle speed but this adjustment does nothing to stop the idle speed from randomly changing. What could be causing this to occur? Thanks 2 Flights

[Marcarl]

Check your work, and try to get the idle down to about 800 to 900 while you do the sync. Also, you need to readjust the idle to keep it at 900 during the process. The fluctuations sure sound like an out of sync to me, and sometimes we don't get it right the first time.

[slick97spirit]

Some of the others on here who know way more than me will chime in, but from what I understand a stuck float can cause this.

[Mike G in SC]

Another in the "for what it's worth",,,

I once mentioned using the Carbtune to my Yamaha shop mechanic Matt.

He rolled his eyes. This was after I sat in on a small clinic where 5 of us had them and got nowhere on one difficult RSTD. (Which he healed.)

 

He made a comment to the effect of, "you have to get the 3rd carb set before you go anywhere. Then you balance the others to #3." So, he was saying that the #3 is the baseline. He did not tell me how to get #3 set. But later when I had the shop set the mixture on each and sync it for me,,,, everything ran GREAT.

 

Like I said, for what it's worth.

[GeorgeS]

I would run a good dose of Sea-Foam in the Gas.

 

Then re-do the Sync. Also, be sure that the Throttle " Pull " cable at the

Left Fwd, carb, has about 1/16 to 1/8 inch of freeplay, before the Linkage starts to move, when actuating the throttle.

 

Also, check for Intake leaks, between the Air cleaner and the Carbs, and the bottom of the carbs, at the intake manifolds.

[Yammer Dan]

I would run a good dose of Sea-Foam in the Gas.

 

Then re-do the Sync. Also, be sure that the Throttle " Pull " cable at the

Left Fwd, carb, has about 1/16 to 1/8 inch of freeplay, before the Linkage starts to move, when actuating the throttle.

 

Also, check for Intake leaks, between the Air cleaner and the Carbs, and the bottom of the carbs, at the intake manifolds.

 

 

:sign yeah that: Sea-Foam cures 90% of our carb problems.

[tbbrider]

How much do you use in a tank of gas?

[Marcarl]

How much do you use in a tank of gas?

Generally 1 can for a tank full, but if you have problems I would go 1 can for a half tank or less. After you got that through and have run a clean tank of gas through, I would then do an oil change with filter.