carb question

[Whit]

See picture below. I noticed that the plug has come out of my left carb. Does anyone know what Mikuni used to plug the holes?
I was thinking about threading it and putting in a screw with a rubber washer. //Pat

[GT750Battleship]

hi,a suitable rubber bung,a little bit of three bond..appropriate colour ?
or plug with JB Weld,is this hole a blind one buy the way ? I'm not familiar with the early carbs...I have a '76A model
Cheers,
Roger

[Whit]

Not sure what you mean by a blind hole, but I expect it will blow fuel out of it. It looks like Suzuki has some kind of silicon or wax type substance in the other carbs. Also the little pin that goes in the slide slot almost came out. It too has lost its silicon which was holding it in. I noticed one of the other carbs has been fixed with jb weld. Whatever this filling is made of seems to be giving out after 40 years. The carbs are for GT750 K model. //Pat

[GT750Battleship]

Sorry,a "blind" hole, one you can't see daylight through,has a bottom !

Cheers,
Roger

[jabcb]

Isn't that where the vacuum line connects to the left carb?

You could fix your problem by installing a carb barb.

[Whit]

No the vacuum is on the side of the carb and has a brass fitting which looks identical to the fuel inlet. Mikuni must have made these carbs for several different bikes as there are several plugged holes. //Pat

[pearljam724]

Fuel won't blow out. That cylinder however, should be running much leaner because that cylinders intake will be sucking in additional air. Read your plugs. Unless, you find a donor set of carbs to replace that plug. I seriously doubt, you will find the exact replacement. Use a tap and die set for any machined bolt fairly close to the proper length of your liking. Most carbs have a similar set up in that they have bolts machined into the bores of the carbs to allow someone to hook up a manometer tool to synchronize a set of carbs properly. Rather than doing what is called a bench synch. Using a manometer is the most accurate way of synching carbs due to uneven cylinder and ring wear among each cylinder. Just carefully tap a thread and it'll be fine. Worst case scenario, if you screw it up. All you have to do, is step it up an additional size in diameter. A rubber washer won't hurt, but isn't necessary. As long as the hole is threaded properly. Use a fine thread. You could also use a barb with a rubber cap like suggested above. Just make sure both are fairly snug. If you're gonna tap a thread. Remove the carbs or air box, so you can clean out the shavings. Anything to plug the hole and seal it from air will work.

[jeff g]

Also the little pin that goes in the slide slot almost came out. It too has lost its silicon which was holding it in.

Fix that IMMEDIATELY!!!!!!!

If the pin comes out, the slide can turn a little and get stuck at wide open throttle. That's the last thing you want to happen when you shut the throttle coming in to a curve hot. I'm not 100% on the Buffalo, but on the 380 and 550, you can stake the pin in the carb body so that it doesn't back out.

The Kawi H2 had that issue early in the 1972 model. They recalled the carbs and replaced them with a different design. On the Kaw, the original pin was plastic and it would break, allowing the slide to turn and stick in the bore.

Jeff

[Suzukidave]

That should be a barb for the vacuum port for the petcock .

[Whit]

I put a little JB Weld on the pin. I see that the PO had already done the same to the other two carbs. Thanks everyone. //Pat