Carb syncing

[D.T.]

When I sync the carbs on my 850 should the outer cylinders (1,4) have a bit less vacuum levels than the inboard (2,3) cylinders? If so, what is the reasoning for this?

[friedshrooms]

nope they should all be even and you sync them to the #3 carb.

[BassCliff]

Hi,

The 1980 and later GS850 models have a "pre-muffler" crossover in the exhaust between cylinders #2 and #3. I'm not sure of the reason for the design, but this is from the service manual.



The '79 and the other bikes with straight 4-n-2 exhausts do, in fact, balance the vacuum straight across all 4 cylinders.

Don't worry too much if you can't get it exactly exact. Here was my latest sync and my bike runs fine.




It is possible to remove the crossover and install straight connector pipes in its place. Then you can balance the carbs straight across. I also don't think that you would kill your motor if you do balance straight across with the crossover in your exhaust. I'm just letting you know what the factory manual says.

Thank you for your indulgence,

BassCliff

Thank you for your indulgence,

BassCliff

[850 Combat]

According to the manual, 2 and 3 are different than 1 and 4. I always set mine all alike.

[D.T.]

Nice Basscliff!

So it's all about the exhaust crossover. I'll check the sync again and try the #1 and #4 a bit HIGHER than #2 and #3.