Carb Sync Procedure

[aujax]

Hi,

I've got a '79 gs750e, running pretty well. It has the carbs with the plungers and no diaphragms. I have the sync guages with the needles (came with almost no instructions) and am ready to sync them. Anyone have a step-by-step set of instructions on how to do this properly so I don't miss anything? Are the 1 and 4 carbs supposed to be higher than the 2 and 3?

Thanks,
aujax

[Nessism]

Do you have a service manual? There is usually a procedure in there.

Basically it's pretty easy. First remove the fuel tank and the top of your carbs. Attach in your intake port adaptors. Pinch off the vacuum line normally running to the petcock and rig up some sort of remote fuel tank - I use a chunk of 2.5" pvc pipe with a cap on one end, which has a threaded nipple attached. Pretty simple and cheap.

Hook up the gauges and start up the engine and let it run til warm, you should have a fan blowing on the engine. The adjusters are on top of the slides of your carbs. For early GS bikes without a crossover pipe in the exhaust, set the vacuum level equal for all carbs. Engine should be running at approx. 2500 rpm when doing the sync.

Very simple.

Hope this helps.

[BassCliff]

Hi Mr. aujax,

As I understand it, the vacuum levels are all the same if you have a true 4 into 2 exhaust (and VM carbs). If you have a 'crossover' or 'pre-muffler' between the 2 and 3 exhaust (and CV carbs) then the #2 and #3 carbs are set a little lower. It seems that right around 1980 is when Suzuki started using the exhaust crossovers and CV carbs. What does your manual say?

I have a manual for the 8-valve 750 on my website.

Mr. bwringer has a good carb sync guide on his website.

http://www.bwringer.com/gs/carbsync.html

Thank you for your indulgence,

BassCliff

[aujax]

carb sync

thanks guys,

I synched the carbs, which was kind of a pain because the gauges i have (the ones with needles, not the mercury tubes) came with no instructions. How strong of a vacuum should I set them at? I decided on 10mm at idle since the engine over-revved if I went too high. It's a little baffling because the adjustment screws are turned way down so there's not much room left to increase the vacuum on them. There's a green section on the guages that says "normal". Is that where they should be at idle or at a certain rpm level?
even more annoying - my #3 carb is still not idling (the exhaust pipe is cold while the other 3 warm up at idle - it gets hot when i give it gas).

-aujax