Kawasaki Carbs on GS

[Guest]

So here's the skinny...

The local shop and I have determined I have Mikuni VM26, most likely off a '78 Kawasaki KZ900. I have a '78 GS1000. It's bee a big headache getting this thing to breathe and live.

I just ordered a new petcock, fuel lines, and filter:

HERE

The stock petcock had the handle broke, I assume in the prime position because the fuel line came from the petcock, had an in-line shutoff and went to a "T" then to 2 spots on the carbs, between 1 & 2 and between 3 & 4. it had nothing coming from the vacuum nipple on the petcock. the carbs have 2 vents tubes (???) coming off between 1&2 and 3&4 as well.

After I bought the bike, I put pods on it (because it had nothing) and since then it's ran worse. so i did a full carb clean, dip and new gaskets and o-rings. still runs terribly (if i can even get it to start). next I'm doing the petcock, lines etc.

here's what I'm wondering:

• Is there some vacuum that I need to plug? The new petcock is manual.
• is there something else that's making this not start or run? The only way I got it to start was a lot of tries with starting fluid. then it still dies. I can get it to a point where it'll idle but try to take off on it and it'll die again if you're not riding the clutch.

I'm a newbie and have been trying to read all over this site and have been through bassCliff's stuff, but having these carbs on it has been hell, everythings in the wrong place! I've tried turning the air/fuel screws too.

Help?

[chef1366]

Get the fuel flowing with the petcock and jet it for your bike.
Look here for jetting.

http://www.thegsresources.com/_forum/showthread.php?t=73723

[notronk]

Get the fuel flowing with the petcock and jet it for your bike.
Look here for jetting.
http://www.thegsresources.com/_forum...ad.php?t=73723

Thanks! So i took screen shots of the posts pertaining to my model. they don't mention which jets to change if I'm using pods and not an airbox. Also, how do I know which of my jets to keep? And what sizes they are? Do I have to change them all? They didn't look damaged.

[azr]

Why don't you get a proper set of Suzuki VM26mm carbs and an airbox?

[azr]

I just looked thru your past posts and pictures, as far as I could see you do have the proper carbs for your bike. Mikuni 26mm for Suzuki. I could even see the 'one' fuel connection in one of your pictures from your carb rebuild. Maybe I'm confused but it sounds like you're trying to connect fuel to the vent tubes on the carbs?? or maybe you are trying to say that was how it was when you bought the bike?? any who...the fuel line goes to the middle T between 2&3, the vacuum port on the carbs in the tube on #3 carb, if you're not using a vacuum petcock you must plug that port. Also, make sure all the vacuum screws are in place on each of the intake manifolds, just thinking out load why it won't start. I'm guessing you did a good bench synch when you rebuilt your carbs...right?

[notronk]

I just looked thru your past posts and pictures, as far as I could see you do have the proper carbs for your bike. Mikuni 26mm for Suzuki. I could even see the 'one' fuel connection in one of your pictures from your carb rebuild. Maybe I'm confused but it sounds like you're trying to connect fuel to the vent tubes on the carbs?? or maybe you are trying to say that was how it was when you bought the bike?? any who...the fuel line goes to the middle T between 2&3, the vacuum port on the carbs in the tube on #3 carb, if you're not using a vacuum petcock you must plug that port. Also, make sure all the vacuum screws are in place on each of the intake manifolds, just thinking out load why it won't start. I'm guessing you did a good bench synch when you rebuilt your carbs...right?

Here's pics of the identical set of carbs that came with the bike. these are the old ones, they're locked up.

Here's how it was setup when I got it:

Fuel goes in to a "T" from the bad petcock to these spots:




2 Tubes are just sticking up out of these spots:

[notronk]

Here's the set that's on the bike. you can see the "T" goes down, and the other tube comes up. same on the other side. I don't see anything else where the vacuum would be setup. this is just how it was when I got it.

[azr]

ahhh yes, Kawasaki carbs indeed, they sure look 'close' to suzuki ones. I don't know the kawi carbs at all, I'm not sure if one of those vent tubes is a vacuum or not, easy enough to tell when you try starting it I suppose. Sure sounds like you have a major vacuum leak though, are you spark plugs getting any fuel? Sometimes the type of carbs you have doesn't have a vacuum on them, such as VM smoothbores, and maybe the kawi carbs I'm not sure, in that case lots of guys will take out a vacuum port screw and put in a threaded nipple for a vacuum port. Check your vacuum screws on each intake and make sure they are all there. The type of pods you've bought are known for not working well, some guys have had success with taping 1/2 or more of the pod over, just a thought. What main and pilot jet changes have you done to the carbs to compensate for the pods?

[azr]

Here's a handy link for you, gives you a starting point for your jetting changes you're going to need to make. That or get a stock airbox.

http://motorcycles.wikia.com/wiki/Rejetting

[chuck hahn]

They will work if you jet them to the 1000s jet sizes as Bill suggested. The fuel can be run with the crossover as was shown..but i would make it look better than all those hose clamps do.

The two brass nipples are the vents i assume. As long as you can find a vacuum port on them for the petcock your good to go. If they dont have a vacuum port, then use a manual pingel style petcock valve..just be sure to turn it off when you leave the bike so fuel can accidentally overflow and fill the crankcase.

If theres a vacuum nipple, then simply replace your broke petcock with a new on for the 77/78 GS750s..same petcock but the nipples face different directions than the 1000s did but it fits right up no problems. And the 750s are about 1/3 the price of a 1000 petcock.

I suppose MAYBE you could use something like a vacuum syncing adapter in one of the ports on the intake manifold as a vacuum supply for the petcock also. Put it in and run a vac line up to the small nipple on the petcock.

[chuck hahn]

PS.......The one brass nipple looks like its full of mud or something. Get the VM kit from robertbarr here on the forum at his website ( cycleorings.com ) and rebuild them..by this I mean the following::

FULL DISASSEMBLY

24 hr dipping of the carbs bodies and hard parts in Berrymans carb dip. Remove the basket and 2 carb bodies will fit in side by side to speed the cycling times up.

Poke all the holes in the pilot jets and emulsion tubes clean with a fine wire from wire brush. Note there is a small hole in the tips of the pilots..they must be poked open too. Many folks miss this.

Go to this link and study up on the rebuild tutorial...

http://members.dslextreme.com/users/bikecliff/images/vm_carb_rebuild.pdf

Heres a link to my favorite gasket place. get 4 packs of top and bowl gaskets for just 9 dollars. Which is less than the price of 1 from the dealerships....about half way down youll see them on page 5.

http://www.siriusconinc.com/search_result.php?make=3&model=&part=1&partno=&x=44&y=13&search=search&start=100

[Steve]

Here's a handy link for you, gives you a starting point for your jetting changes you're going to need to make. That or get a stock airbox.

http://motorcycles.wikia.com/wiki/Rejetting

Nice link, but I have a problem with their math.

They start with a 112.5 main jet. Adding 6 sizes, they end up with a 118.5. Since the size increment is 2.5, I feel that a "six size" increase should be a 127.5.

.

[chuck hahn]

Heres another chart that may be useful

http://www.jockeyjournal.com/forum/showthread.php?t=64769

[hjfisk]

I believe that the Kawasaki gets it's vacuum from a nipple on the intake hoses, where Suzuki had them on the carb body.

[chuck hahn]

Harry.....I am unsure of "all" the Kaws setup, but i do know the Concourse used a nipple at the top of the number 2 intake manifold for vacuum....which led me to suggest using a vacuum nipple off one of the sync ports for the petcock..thus he can get the new 750 petcock, rebuild the carbs, redo the fuel feed crossover, and be good to go.