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1977 Suzuki gs750 cold cylinder

2161 Views 37 Replies 6 Participants Last post by  TrialsRider
The bike has one cold cylinder on the far right of the four. It gets spark but I’m not sure how it’s not getting gas or air. The bike is having a loss of power and I believe this it, I’ve been debating on getting new carbs but I don’t think that would fix this.
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Check compression and valve clearance first like TR said. That bike has a stupid tight valve clearance spec ( like .003”) and the check interval is 3000 miles. Yes. Every oil change basically.

if the clearance has gotten tight, it’ll hold the valve open slightly and compression will drop.
I ran a compression test and hit 127. Is that good or bad
On how many cylinders? More telling is how close they are together. Test hot and cold. If one cylinder drops , or shows a really big difference when hot, that’s a pretty good indication you have tight valve clearance on that cylinder
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Before doing all this work, how is changing the valve clearance going to magically make the cylinder work again, could the carbs possibly be dirt and just not letting gas through?
I answered that in my first post (post#6)

And BTW, you NEVER start carburetor work on these bikes before you sort out the valve clearances. Tight valve clearances will throw off everything in the carbs.
How many parts on #4 carb are Not interchangeable with the parts on one of the other 3 carbs? Suzuki doesn't build the carbs, they buy them and it would become costly to order them all significantly different, they generally avoid that.
They are different. The passages are drilled so the adjustments face outward. And 2 & 3 have the fill pipe drilled all the way through, where as 1 & 4 have the fill pipe on one side facing inward. #1 is the only one that has the mount for the choke lever, #3 has the port for the fuel tap, etc. There are other differences, too. You can’t just swap carb bodies around
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Yeah all the parts are interchangeable but there’s this bracket type thing on the back that holds all four together so can’t exactly swap carbs but I can swap parts around
While you can’t swap the carb bodies around, you absolutely should take them off the bracket to clean them thoroughly. You have to clean ALL the ports and passages
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Must be why they came up with those strange double barrel setups on the later models.
Maybe why I stopped riding Suzuki when they stopped building 2-strokes too.
most inline 4 cylinder carb banks are the same way. Tha way gas fills the bowls, alone, means 1 & 4 are unique. 2&3 might be able to be swapped on some bikes, but the air screws would be on the wrong side usually,

as a matter of fact, I haven’t come across one bike that had interchangeable carb bodies OEM
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