Q&A: Carb kit problem with my Suzuki GS750

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Ron Watson asks: I am a bike nut from the UK, but now living in Australia and I read Classic Motorcycle Mechanics regularly. I recently imported two Suzuki GS750s from the States for restoration. As I like to do as much as possible myself, I invested in an ultrasonic cleaner for the carbs and an aqua-blaster for the engine, with the idea to start a small business.

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However my query to Q&A is in connection with the carbs. I purchased a carb kit online and checked everything was there to be replaced and stripped and ultra-sonic cleaned everything, then began replacing jets etc. Now, herein lies my problem: in the carb base there is a jet and it is not mentioned whatsoever in the manual and unknown to me it is set at factory settings so of course I have no resetting information.

Can you help? How many turns does it need, or has it got to be done per individual carb?

 

Mark and Steve say: I don’t know which manual you have been reading but in the official Suzuki GS750 manual there is a photograph of the underside of a row of carburettors with arrows pointing to the screws you refer to and the note: “Do not disturb the screw shown in the photo.” But, as you say, it is too late now!

These VM series carburettors are a bit unusual in that there is a separate adjustment for air and fuel for the idling circuit. What you are looking at is the fuel adjustment. The other screw you see on each carb is the air adjustment and this should be set to either one or one and a quarter turns out, depending on which page of the manual you are reading: pity they couldn’t get that right.

If I were you I would set the fuel screws at one turn out and see what the idling is like. Then make adjustments a quarter of a turn at a time. Turning clockwise will weaken the mixture: if you have an exhaust gas analyser that would help.

  • Originally from our February 2018 edition.

We hope this helps Ron! If you have any queries yourself, feel free to ask away. Simply fill in the form below:

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