Carb help

[rputney01]

My bike was running poorly; bogs on the low end, idles poorly and starting to backfire. It seems that it is time to try my hand at carb disassembly. The bike is a '79 GS1000S. I was told that it has smoothbores, but don't honestly know. They are Mikuni, but I can't see a model number on them.

In any case, I downloaded the carb cleaning & repair tutorial but alas, my carbs are a different type. The Haynes manual says to remove the tops, remove the bolts from the bellcrank, then remove the screw retaining the claw plate and remove the throttle rod. I can't find a claw plate and the throttle rod appears to be held in place by a lock washer of some type (pic).

This is my first venture into carb work. I'm a noob and have only had the bike for about 10 months, so I appreciate your patience and advice.

Thanks.

[rputney01]

Here is a picture of the carbs

Perhaps this will help in indentifying them.

Thanks.

[hampshirehog]

They ain't standard VM28s that's for sure. A photo of the bottom or the venturi would help more in id.

Nevertheless, your symptoms do suggest a fuelling problem. This could be leaking / split carb to head rubber boots or bad O rings or bad carb to airbox connections. I'd check these and replace the O rings as a matter of course, they're cheap and Robert Barr on here provides an excellent service.

Apart from maybe how you split you carbs the principles are the same on all the VM carbs so the carb rebuild tutorial is still helpful. You might not have the fuel meter screws on your carbs - the ones on the underneath - and you might have air pilot jets that screw in at foot of the carb mouth. Those will most likely be your main differences.

This is a good bedtime read and shows how all the fuel and air passageways meet up on the VMs.

http://www.mikuni.com/pdf/vmmanual.pdf

[rputney01]

Thanks

I'll get a pic tomorrow after I take them apart. If I can figure out the throttle rod issue, I'll be in good shape, I think. Thanks for the read!!

Cheers.

[BassCliff]

Hi Mr. rputney01,

Did you download the CV carb rebuild series, or the VM carb rebuild series?

Click here for the VM carb series.

That may be more of what your looking for. Perhaps it will help. Keep us informed.


Thank you for your indulgence,

BassCliff

[rputney01]

Thanks Mr. BassCliff

Hi Mr. rputney01,

Click here for the VM carb series.

That may be more of what your looking for. Perhaps it will help. Keep us informed.


Thank you for your indulgence,

BassCliff

It was indeed, sire. Renewed hope for the morning. By the way, the bike had a Kerker 4-into-1 and pods when I got it. The old pods were pretty shabby so I put K&Ns on it. I also put in new boot o-rings over the past winter, so I'm pretty sure it's a carb problem.

Thanks,
Bob

[rputney01]

Down the throat

[quote=hampshirehog;894386]They ain't standard VM28s that's for sure. A photo of the bottom or the venturi would help more in id.

Here is a pic of the tube.

Thanks.

[rputney01]

Side view

Another pic, from the side view.

[BassCliff]

Hi,

There's also a VM carb manual on my website that you might find handy. Help yourself.


Thank you for your indulgence,

BassCliff

[SqDancerLynn1]

29mm smooth bores! You can barley see the big drain bolt on the float bowl

[rputney01]

29mm smooth bores! You can barley see the big drain bolt on the float bowl

Thanks for the ID. Would you know how to disconnect the throttle rod so that I can separate the carbs?

Also, is 29mm smooth bore enough to order kits? Any recommendation on where I should best get the rebuild kits from?

Cheers.

[Craiger]

Hey Bob. After you get them cleaned and back together, get ahold of Greg (Spindle). He should be able to help you sync them with his carbtuner....and he lives pretty close to you.

[rputney01]

Hi Craiger

Glad to hear that you are feeling better. Actually, I figured that if I'm going to learn how to do this stuff, I should buy the tools. So I ordered a Carbtune and a Colortune yesterday. It is coming from the U.K., so it probably won't get here until next week. I'm breaking down 1 carb per evening to dip, so I won't start putting them back together until this weekend. I ordered kits from Z1 that should be here tomorrow, so I'll have new gaskets, o-rings & such.

I hope that a bench synch is sufficient to get it running, so I may contact Spindle afterward to get his expertise. It would be great if I didn't have to learn everything the hard way.

Thanks,
Bob

[Craiger]

Glad to hear that you are feeling better. Actually, I figured that if I'm going to learn how to do this stuff, I should buy the tools. So I ordered a Carbtune and a Colortune yesterday. It is coming from the U.K., so it probably won't get here until next week. I'm breaking down 1 carb per evening to dip, so I won't start putting them back together until this weekend. I ordered kits from Z1 that should be here tomorrow, so I'll have new gaskets, o-rings & such.

I hope that a bench synch is sufficient to get it running, so I may contact Spindle afterward to get his expertise. It would be great if I didn't have to learn everything the hard way.

Thanks,
Bob

I think we learn the best that way. Just hope it doesn't get too frustrating for you.

You thinking you'll be able to make the Fall Meet and Greet? Some of us will be riding up together.

[rputney01]

I think we learn the best that way. Just hope it doesn't get too frustrating for you.

You thinking you'll be able to make the Fall Meet and Greet? Some of us will be riding up together.

I hoping so. My wrist is fine now, so assuming I get the bike functional, I should be in. I seem to spend a lot more time wrenching than riding.