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Rebuilding KZ900 Mikuni's 18 Jul 2018 10:33 #787171

  • ubertalldude
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As stated in my intro post I'm helping my buddy fix up his late father's KZ900. First order is the stock Mikunis, about which I have a few questions. 

1 - The pilot mix screw is threaded in from the bottom of the carb assembly, down below the float. This does not match the diagram I see on partzilla and others. Is this indicative of a different carb? Will the stock air mix screw o-ring fit on this?

2 - I want to know if this is a full rundown of the rubber o-rings that need to be replaced (I plan to just deep clean the float and seat, and jets.) 
 - Pilot mix screw o-ring
 - Bowl drain screw o-ring
 - Choke plunger o-rings
Am I missing anything? 

3 - Is there any consideration to tuning I need to make given that this bike was supposedly bored/sleeved out to 1000cc from the stock 900cc? 

Outside of this I will do a bench sync and set the float height per the FSM, which I've acquired a digital copy of. 

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Rebuilding KZ900 Mikuni's 18 Jul 2018 11:20 #787178

  • Nessism
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I'm not familiar with all the Kawasaki Mikuni variants but those pilot fuel screws were standard on the Suzuki version VM26's.  The O-rings are different from those on the pilot air screw.

Cycleorings.com sells a cheap kit for VM's which are very useful.  Not sure if every O-ring is the same but I think you will find some of the pieces useful.

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Rebuilding KZ900 Mikuni's 18 Jul 2018 12:43 #787181

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900's were fitted with vm26's as standard. There are a few versions of vm26. Mix adjuster screws on the underside. This is a fuel mix screw and increases/decreases fuel in the pilot cicuit. Mix adjuster on the body side, this increases/decreases the amount of air in the pilot circuit. Then there are vm26,s with both fuel and air mix screws.
Mix screw o rings are not interchangable between fuel and air screws as they are different diameter.
Which vm26 do you have?

Z1000J2 somewhat modified!

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Rebuilding KZ900 Mikuni's 18 Jul 2018 14:08 #787185

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They don't sound like stock carbs. They might be VM 28's. Pics of the carb bottom, top, etc?
Steve

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Rebuilding KZ900 Mikuni's 18 Jul 2018 14:59 #787189

  • zed1015
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You have VM26mm carbs common on z900 and 1000.
Stock VM28's on the Kawasaki Z1R,Mk2,ST only had the air mix on the side and never a fuel mix on the underside.
VM26's and VM28's from Suzuki GS's have BOTH fuel and air mix screws.
AIR CORRECTOR JETS FOR VM CARBS AND ETHANOL RESISTANT VITON CHOKE PLUNGER SEAL REPLACMENT FOR ALL CLASSIC AND MODERN MOTORCYCLE CARBURETTORS
kzrider.com/forum/23-for-sale/611992-air-corrector-jets-





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Rebuilding KZ900 Mikuni's 18 Jul 2018 17:49 #787202

  • ubertalldude
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Yes it sounds like they're VM26's, I'll have to take a look at the carbs again and see if maybe the pilot fuel mix screw is present on the top of the body. I know on my VN750 the pilot mix screw is hidden from the factory, I wonder if that's the same for these since I really did not see the pilot fuel mix screws on the topside of the carbs, but I very well could have missed them. Even cycleorings.com mentions the air mix screw on the bottom of the carb, even noting they don't list it on factory exploded diagrams. 

Either way, it seems like cycleorings.com has a great o-ring kit that includes the choke plunger, pilot air, pilot fuel, and bowl drain o-rings, which appears to be o-ring I need. I believe I also need the valve seat washer, as it seems like we lost one. Definitely need new fuel inlet tees and gaskets. 

Any idea what an approximate stock setting on each of these screws would be? I typically figure 1.5 - 2 turns from seated, but have never dealt with independent pilot air and pilot fuel mix screws. 

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Rebuilding KZ900 Mikuni's 18 Jul 2018 18:20 #787204

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You should have air bleed screws on the side of the carbs. If so start with 1 1/8-4 turns.
Steve

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Rebuilding KZ900 Mikuni's 19 Jul 2018 08:07 #787217

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There are two versions of the VM 26 SS carbs on Kawasaki 4 cylinder bikes.  The first was used on the KZ900 and had fuel/air screws on the side of the main body.  The second, used in 1977  had the fuel/air screw hole blocked off and used pilot screw adjusters on the underside of the bowl near the front of the carb.  (front meaning closest to the intake manifold when the carbs are mounted on the bike)

In later years KHI added an accelerator pump on the carbs, usually on #2, and as well they went back to 28 mm outlets.  Of all of the versions I like the '76 one best.  It's the simplest to work on, although synch is a bit more difficult than the VM 28 SS version.  I have a set of '76 version on my 1980 KZ1000 LTD.  The bottom end is original.  The top end is off a '78 KZ1000.  This bike has a Z1 air intake and a V&H 4/1 exhaust.  It runs very well and pulls hard with those carbs, particularly above 4,000 rpm.
I have several restored bikes along with a 2006 Goldwing with a sidecar. My wife has a 2019 Suzuki DR 650 for on and off road.
The following user(s) said Thank You: Nessism

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Rebuilding KZ900 Mikuni's 20 Jul 2018 11:55 #787277

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hardrockminer wrote: The second, used in 1977  had the fuel/air screw hole blocked off and used pilot screw adjusters on the underside of the bowl near the front of the carb.  (front meaning closest to the intake manifold when the carbs are mounted on the bike).


This sounds like my configuration. I'll have to verify the absence of the mix screws on the top/side (diagonal installation from what i can tell in the exploded diagrams) to be sure, but this is very helpful. Thank you

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