Syncing Throttle plates and throttle stop.

[kmarts]

Hi All, No stranger to wrenches but this is my first dual carb machine. I've pretty much done everything by reading this site and the manual, you guys are pros and I appreciate all the info you freely post.

I Bought a 97 GSX (787) on the cheap, was running lean (runaway). So I've gone through and rebuilt the carbs, replaced fuel lines, etc... What I'm struggling with here is syncing of the throttle plates. I've had the carbs on and off a couple times since rebuilding and have had the doo running, but have been waiting for new base gaskets. Now that they're in, I want to do this the last time... Properly.

If you follow the manual, first step is to turn out the idle screw and make sure both plates are both fully closed. Manual shows this with the linkage bar disconnected. Then connect the linkage bar and make sure they're still closed.

Next in the manual is throttle cable adjustment which specifies to hold the throttle wide open. In that position the spacing between the throttle stopper is .5mm (1/64") away from the carb body.

But if you adjust according to this, your throttle plates will no longer fully close, at least mine don't seem to. Additionally, there isn't slack in the cable. The first time i put them back in and adjusted like this it idled high until i backed off the throttle cable tension.

So how critical is that .5mm WOT spacing?
Should i just sync the carbs closed and not worry about it?
how much slack (by feel or sight) is appropriate in the throttle cable?
Before turning in idle screw should the throttle plates be fully closed?

Thanks

 

[mikidymac]

The way I do it is to count the turns out on the idle screw until it isn't touching the plates.
Then if you stand on the exhaust side of the engine and hold your head over the carbs and snap them open and let them snap closed you can hear which one is closing first. Adjust the link rod until you can't hear one closing before the other. It's actually pretty obvious when you are doing it. Then set the idle stop screw back to where it was. Next set the throttle cable so you have about 1-2 mm free play at the throttle lever before the carbs open. Finally set the oil pump arm alignment.

 

[kmarts]

So I shouldn't worry about the throttle stop gap at WOT?

 

[Mekanix]

Nope. You don't have to hit the stops. just make sure the butterfly valves open fully.
Go with what Mikidymac said and that will allow you to synchronize them.
Also you can look down the carbs with a mirror and check at full throttle if the valves line up with the ventury in the center.
Then turn the Idle screw up to where you need it to idle.
And then adjust the cable so that you have just slight play at the handle bar.
Adjust for 3000 rpm out of water or 1500 in water and make sure your oil pump is lined up.

 

[kmarts]

Nope. You don't have to hit the stops. just make sure the butterfly valves open fully.
Go with what Mikidymac said and that will allow you to synchronize them.
Also you can look down the carbs with a mirror and check at full throttle if the valves line up with the ventury in the center.
Then turn the Idle screw up to where you need it to idle.
And then adjust the cable so that you have just slight play at the handle bar.
Adjust for 3000 rpm out of water or 1500 in water and make sure your oil pump is lined up.

Yeah makes sense that you're only concerned with it NOT hitting the stop, manual says that it should be within .5mm and to adjust accordingly. I read it to mean that you should be adjusting to make that .5mm gap instead of it shouldn't be closer than that.

Thanks for the help.