TOPIC:

750 twin carb sync howto:

Obviously, first you need the synch gauges, like this:
(Available from Z1 Enterprises, and others)


Get the gauges ready to use, then start the bike and allow it to warm up.

After bike is warm, shut it off and remove the hose that connects the two carb manifolds on the bottom.

Connect two of the carb synch hoses to the two nipples where the hose was connected.

Remove the tank and twist it 180 degrees and set it on top of a stool or something that is about frame height, that way you can leave the fuel lines hooked up.

Get 8mm, 9mm and 10mm open end wrenches (because I don't remember the actual size needed), and loosen the locknut on the carb synch screw that is between the two carbs and pointed towards the rear.

You need a long screwdriver with a small tip to reach from the rear of the main backbone tube (just in front of the airbox) to the synch adjuster screw.

Start the bike (do "NOT" rev it up) and adjust the carb synch adjuster screw until the level in both synch gauge tubes is the same.

Hold the screw with the screwdriver to keep it from turning and tighten the locknut.

Adjust the idle back to normal with the idle screw on the left side.

Remove the carb synch gauges and reassemble everything.

Afterwards, I adjust the idle mixture screws (small brass screws on each carb) for the highest rpm, and go back and forth from one carb to the other until turning either one results in reduction of idle speed, while keeping the rpm reasonable by adjusting the idle adjustment screw on the left.

Did this a couple of weeks ago on my 79 750 twin, made a lot of difference.

Of course this as after I did a complete tune up, new plugs, Accel coil, converted to electronic ignition, valve lash adjustment, rebuilt carbs, etc.

Beatpoet wrote:

MadKaw500 wrote:

Hi, first thing is to remove that windshield, it'll start running better...he he he..

An old windshield with *any* scuffing on it will completely blind you at night the first time you meet an oncoming set of headlights!

You're not supposed to look "through" the windshield, you're supposed to look "over" it.

alexk243 wrote:

Ok, well the consensus over at advrider.com is that it is not an exhaust leak but and oil leak from the valve cover.

I am still looking for advice on the project and also the procedure for syncing carbs.

Looks like steell has you covered on the carb sync....

...but I;ll agree, it looks like somebody re-used a valve cover gasket, and that can cause it to leak exactly like that....

so pretty much if the cover looks fine (no dents/scratches) a new gasket and cleanup will do the trick?

steell wrote:

...Afterwards, I adjust the idle mixture screws (small brass screws on each carb) for the highest rpm, and go back and forth from one carb to the other until turning either one results in reduction of idle speed, while keeping the rpm reasonable by adjusting the idle adjustment screw on the left.....

Interesting... kinda' how I used to do it, but I could never get it 100% right.... so I bought an old "Colortune" from eBay... one of the best buys I've made yet, and I know it is set EXACTLY, regardless of my (in)ability to perceive the correct setting... /)