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Kawasaki Carbs on GS

  • Thread starter Thread starter notronk
  • Start date Start date
N

notronk

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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?
 
Why don't you get a proper set of Suzuki VM26mm carbs and an airbox?
 
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?
 
azr said:
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?
Click to expand...


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:

10009844_10152273055506119_1710350853_n.jpg



2 Tubes are just sticking up out of these spots:

47443_10152273055511119_717679437_n.jpg
 
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.

1902861_10152273055491119_1775338922_n.jpg
 
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?
 
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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.
 
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_...t=1&partno=&x=44&y=13&search=search&start=100
 
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I believe that the Kawasaki gets it's vacuum from a nipple on the intake hoses, where Suzuki had them on the carb body.
 
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.
 
Chuck, the photo is an old set that came with the bike too. I did a full disassemble and dip with new gaskets and o-rings from Robert Barr.

I'm waiting on new hoses and better clamps with the my order for the new petcock. i ordered a manual petcock so I just want to make sure there's now vacuum leak.

I havent rejet because i had no idea which ones to switch out and with what, to use pods. and because these are Kawi carbs (which took awhile to find that out).

You guys have been awesome so far thanks!!
 
I dont see any vacuum ports on the pics of the Kawis you posted. the two brass nipples are bowl vents which should have a hose down between the tranny and swing arm out the bottom of the bike.

I dont think youll have any vac leaks from the carbs themselves, but did you put in new intake manifold orings too? I would hook them up and fire it off.
 
chuck hahn said:
I dont see any vacuum ports on the pics of the Kawis you posted. the two brass nipples are bowl vents which should have a hose down between the tranny and swing arm out the bottom of the bike.

I dont think youll have any vac leaks from the carbs themselves, but did you put in new intake manifold orings too? I would hook them up and fire it off.
Click to expand...

yeah, i got new rings in the boots too. so i put it all together and wouldnt start. after way too many tries with starting fluid sprayed in the carbs, finally started, but soon died. and didn't run or sound any better than it did before i did the carb clean.

now i have the petcock off because it was broke anyways, i ordered a new one with hoses and clamps and filter from Dime City yesterday. so i'll try starting it again once that's on.
 
Where is the big idle knob set at? Did you do a bench sync before installing them?

If the idle knob is set too far in ( opening the slides ) the VMs dont like to start the bike very easily. I set the knob at about 1 3/4 to 2 full turns in JUST AFTER it touches off on the throttle cable linkage. Dont be twisting the throttle and all that either..just choke and hands off the grip.

To bench sync, you have the idle knob completely off and not touching the throttle linkage. Next, remove the top covers and loosen the 8 MM nuts. Now turn the inner adjustment screws till all the slides are all the way down. Then you turn each adjuster till theres maybe a 20/1000 gap between the bottom of the slide and the throat of the carb...make all 4 look the same way.

Now touch off the idle knob and do the turns in. Should be real close and the bike should fire. May have to fiddle with the idle if it doesnt catch rather easily...go in half a turn and try it. If not then go out that 1/2 turn and then another 1/2 turn ( 1 full turn ). Gotta find that sweet spot the carbs like.
 
so after i set the slides, i turn the idle knob in until it touches, then do the 1-2 turns?

and I should rejet before i finish this and reinstall right?
 
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