vm carbs with only 1 mixture screw?

[j.w.napier]

when i first got my bike the #3 cylinder wasn't hitting at all and the fuel was coming out the exhaust and a little in the air box. i think that some even transfered into my oil. so real quick like i went and changed the oil and tore apart the carbs. i found that the fuel mixture screw had been tightened down so tight that the tip broke off in the carb body. so i went on the hunt for a new set of carbs. i got a set of carbs off of ebay and cleaned them up replace the 110 jetts that were in them and everything else from my old set that i could. i put them back on joy all cylinders are hitting,BUT for some reason it bogs down when you twist the throttle not always but most of the time like it's starving for fuel. on the other hand it smells like it is running rich. to much fuel can make it bog down to right? if thats the case with this bike then i don't know what else to do cause in the spot where the air mixture screw is suppose to be it is plugged off and it looks like it came that way from suzuki? if anyone knows how to mix in air or less fuel then please drop in and give me some suguestions.the only think that makes me think that it is lean is the way it bogs down, and the popping and cracking sound it makes while running it around the block. has anyone seen the vm carbs with only one way to adjust the air fuel mixture. on my old set it had the air mixture screw? so i am utterly confused. thanks for any help you all can provide.

j.w. napier

 

[rthor]

I got a set of VM carbs like you are describing off a late seventies Kawasaki KZ650 (only one mixture screw under the float bowl). The carbs seem to be identical to the Suzuki VM type except that the side air screws cavities are definately sealed/plugged from the factory. I mistakingly drilled into the side air plugs thnking they would simply pop out and reveal a screw. No such luck. There is no screw that I could see. I wouldn't go messing with it. If you are going to use these carbs, give them a thorough cleaning and dial in the mixture with the screws under the bowl.

 

[Nessism]

Regarding your original VM carbs, the stuck fuel screw tips can be removed if you use a pointed awl and carefully punch the tip backwards working from the carb throat side. Soaking in PB Blaster for a day or so wouldn't hurt, nore would some heat.

The fuel screws are hard to come by but if you purchase a carb rebuild kit for the GS750 from Z1 Enterprises, the screws come in the kit.

Good luck.

 

[rusty boltz]

Nessism is right I had to do the same thing with the VM carbs on my 79 gs1000. His suggestion saved me some money. I cut the tip off a test light (an awl wouldn't fit in the tiny hole) and used it to knock the tip out going through the slide bore carefully. Everything except the jets in the 750 rebuild kit will work on your old carbs including both new fuel and air pilot screws. And the guys at Z1 got everything here quick! There is a thread in here somewhere with a detailed pictoral explanation on how to remove these screws. I personally would rather have the adjustment of the air mixture screws. The "rich" smell is from incomplete combustion caused by the lean condition. If the mixture is not right it will not burn all the fuel and it will end up going right out the tail pipes. Good luck !

 

[j.w.napier]

it's coming together

it's coming together

i went to my favorite local bike shop king's cycle "good people". the owner operator and head wrencher told me i should mic the throat of the carb. i'm still carb stupid so i had no idea on what he was talking about. he said that my stock carb throats were problly 27 or 28mm and the ones that i've been working on were 26mm. he suggested that i put the 110 jetts back in and see if that didn't clear up some of my prbloems. and believe it or not it cleared most of my problems up. thanks to you guys for all your help i'm sure i'll be back with another post trying to work the bugs out. hopfully i can post some pic's soon. seems like everytime i try to take a pic the batterys are dead to the camera? i still don't know how that happens? any advice on that one? thanks again everyone for the input.

J.W. Napier

 

[SqDancerLynn1]

Your stock carbs should be 26mm VM's. Their are probably internal differences in the carbs-- requiring the larger jets. Maybe different slide cutaways