@ what rpm to sync?

[dtkid]

Hey Folks:

Can anyone tell me which rpm I should use to sync the carbs on my 1981 GS1100E?

[catbed]

as low as you can go is ideal(i think). wait until someone that knows what they are talking about comes by.

[Tom MLC]

I sync my carbs at around 4000rpm. That's where your carbs come off the pilot circuit and start running on the main jets.

[dtkid]

thanks Tom

[Steve]

Can anyone tell me which rpm I should use to sync the carbs on my 1981 GS1100E?

as low as you can go is ideal(i think).

I sync my carbs at around 4000rpm.

As you can see, you will get several different answers, and mine is different, as well. The Suzuki manual (and maybe the others, too) says to do it between 1500-2000 rpm. Personally, I prefer to do it at idle, 1000-1200 rpm. My theory is that is where small differences between throttle openings is most pronounced. Vacuum levels will change as the rpm rises, but will remain rather close.

That's where your carbs come off the pilot circuit and start running on the main jets.

That would depend on throttle opening more than rpm. I am sure you can get 4000 showing on the tach in neutral, and still be on the pilot circuit. On the other hand, you can probably get into the main circuit with a handful of throttle at 2000 rpm, so rpm is not the deciding factor on when the jets transition from one circuit to another. Also, I don't think which circuit is feeding the fuel has anything to do with carb sync. The whole purpose is to get all the throttle butterflies to open the same amount, at the same time.

.

[p_s]

I found I'd get different vacuum differences depending on the RPM. The right two cylinders would pull harder at idle and the left two would pull harder at high RPMs. I tried syncing at 3k and at 1700, and the bike felt MUCH smoother synced at 1700.

(The 550ES is a bit strange though--two double barreled carbs with only one sync adjuster.)

[Steve]

I tried syncing at 3k and at 1700, and the bike felt MUCH smoother synced at 1700.

Gee, I wonder if maybe Suzuki might have had a good guess on where to do it? 8-[

.

[greg78gs750]

uh, yeah, throttle position determines which circuit you are on, NOT rpm