77 GS 750 Carb Question

[budweiser792]

Just bought a 77 GS750 and need to sync and clean the carbs. Is there info I can print off that would show me what the proper sync levels should be and all. Basically a step by step manual on it. If anyone has anything please let me know. Its 90 here today and I have a bike that isn't running

[Dave8338]

Which carbs do you have on your bike...BS or CV? Can you even get the thing to start?

[Steve]

Actually, the BS carbs are a CV-type carb (constant velocity). What he should have on his '77 are the VM carbs.

Bud, you need to get the bike running before you do a carb sync. But, since you asked how...
Remove the seat and tank. Find a way to temporarily get fuel to the bike. If you have a trash can or something you can set the tank on, you can run longer hoses (fuel and vacuum) from the tank to the bike. Make sure the tank is at least as high as it normally is on the bike. It will not work if the tank is below carb level. Find a fan or two to blow cooling air on the bike while you do this.
Warm the bike to operating temperature. Remove the top caps on the carbs. Remove the plugs in the intake tubes and install the vacuum adapters that come with the sync gauge. Connect the gauges, start the engine. Observe the levels of vacuum. Use the adjusters in the top of the carbs to even out the vacuum levels. With your carbs it will not matter what order you do them, but might be best to start with the one that is farthest out of sync with the others. There is no set number that you need to match. What is important is that the vacuum on all four carbs is the same. Some people (me included) do this at idle speed, but the factory manual calls for 1750 rpm during the procedure. Might also help to blip the throttle just a bit to make sure the adjustment is 'set' and does not change.

Also be aware that in the course of normal maintenance, carb sync is the last thing you should do. First check the valves. Then check the point gap and ignition timing. Next check the fuel mixture, then do the sync.


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[budweiser792]

77 GS 750 Carb

The bike runs, what I meant that its not running is that I have the tank off and the seat up and thats why it is running right now. Sorry for the mistake. I did notice that when removing the tank is that the petcock didn't stop the gas so I will need to fix that too. I know other bikes the sync level was in a certain limits. Thanks for the help