Do I have 76 carbs or hybrid carbs?

More
28 Sep 2011 23:19 #480340 by WMKZ900
Do I have 76 carbs or hybrid carbs? was created by WMKZ900
My 76 KZ900 I have owned since 1995 has carbs that have me scratching my head. I do not know if they are the original carbs.

They are 26 mm carb that were first used on the 76 model. However they could be off of a 77 or later. I do not know.

The carbs have the standard air screws on the air filter end of the carb and a pilot screw under the carb on the intake end of the carb.

The question, do I have a hybrid carb that should not have both screws.

The Clymer manual shows a break down of the carb and notes that some have a pilot screw and some an air screw model. Can a carb have both?

The problem is tuning both screws if you can imagine.

The carbs do fine other than the fact it will not idle under 1500 rpm. With 8 screws to adjust it is nearly impossible.

Have and Running
66 Honda S90
71 Honda CB350
71 Kawasaki H1 500
73 Kawasaki H2 750
76 Kawasaki KZ900
06 Kawasaki Concours

Had
65 Honda S65
68 Honda CL 175
71 Honda CB 450
72 Kawasaki H2 750
74 Kawasaki H2 750

Please Log in or Create an account to join the conversation.

  • z1kzonly
  • Offline
  • User
  • Sustaining Member
More
28 Sep 2011 23:33 #480347 by z1kzonly
Replied by z1kzonly on topic Do I have 76 carbs or hybrid carbs?
Wow I never seen them with 2 air mixture screws.
Must have been a Monday thing when they went back to work after 8 hours off. Must have been in the middle of re-tooling the machinery.
Sure would like to see a picture of this.

Livin in "CheektaVegas, NY
Went thru 25 of these in 40 yrs.
I SOLD OUT! THE KAW BARN IS EMPTY.
More room for The Old Girl, Harley 75 FLH Electra Glide,
Old faithful! Points ign. Bendix Orig. carb.
Starts everytime!

Please Log in or Create an account to join the conversation.

More
28 Sep 2011 23:39 - 28 Sep 2011 23:42 #480351 by Patton
Replied by Patton on topic Do I have 76 carbs or hybrid carbs?
Some manual slide carbs have only a side-located pilot air screw.

Other manual slide carbs have only a bottom-located pilot "mixture" screw.

While not having seen one in the flesh, there are discussions about a third version of manual slide carb that has both a side-located pilot air screw AND a bottom-located pilot mixture screw.
And some of the kawasaki.com diagrams for other models show manual slide carbs with both type pilot screws.

Here's a pic of the Yeti carb with "pilot fuel screw" (actually a pilot "mixture" screw) AND a pilot air screw.

As I recall, the tuning suggestion for such carbs with both pilot adjustment screws is to first disable the bottom-located mixture screw by tightening it against its seat, and then proceed using only the side-located pilot air screw to fine tune the carb pilot circuit.

The last two pics show comparison of the two different manual slide carb pilot circuits.

Good Fortune! :)




1973 Z1
KZ900 LTD
Attachments:
Last edit: 28 Sep 2011 23:42 by Patton.

Please Log in or Create an account to join the conversation.

More
28 Sep 2011 23:50 #480356 by Patton
Replied by Patton on topic Do I have 76 carbs or hybrid carbs?
Stock 1976 KZ900 has Mikumi 26mm manual slide carbs with side located pilot air adjustment screws.


1973 Z1
KZ900 LTD
Attachments:

Please Log in or Create an account to join the conversation.

More
29 Sep 2011 09:06 #480413 by WMKZ900
Replied by WMKZ900 on topic Do I have 76 carbs or hybrid carbs?
Thanks Patton for the the info and the diagrams.

I will try closing off the bottom mixture screw and use the conventional air screw for idle mixture adjustment.

Have and Running
66 Honda S90
71 Honda CB350
71 Kawasaki H1 500
73 Kawasaki H2 750
76 Kawasaki KZ900
06 Kawasaki Concours

Had
65 Honda S65
68 Honda CL 175
71 Honda CB 450
72 Kawasaki H2 750
74 Kawasaki H2 750

Please Log in or Create an account to join the conversation.

More
29 Sep 2011 10:38 #480424 by roy-b-boy-b
Replied by roy-b-boy-b on topic Do I have 76 carbs or hybrid carbs?
Always remember,if the screw is in front of the carb body it is a gas mixture screw. if it is behind the carb body it is a air mixture screw.

Look at the diagram on the right. The front screws are for the idle circuit. They should have very sharp adjusting needles and if you screw them in too tight they will break off and the circuit will be clogged.

I would suggest they be set at the factory setting and left alone for the time being. Roy

1979 LTD Street Fighter.1977 KZ1000

Please Log in or Create an account to join the conversation.

  • testarossa
  • Offline
  • User
  • Attack life, it's only trying to kill you.
More
29 Sep 2011 13:43 #480434 by testarossa
Replied by testarossa on topic Do I have 76 carbs or hybrid carbs?
I have no advice to offer on the issue of multiple idle mixture screws but one observation if I may. On the issue of 1500 rpm idle. Are you basing your rpm off of the factory tach? My KZ1000 likes to idle at 1500 rpm according to the original tach, but my particular gauge is a bit "optimistic." As verified by a digital tachometer that is reading from the output on my electronic ignition 1500 rpm gauge = 1100 real. It is possible that your gauge does not read correctly, thus returning a false high rpm?

I have no doubt that having to adjust 8 screws to get your idle mixture correct would be a hassle that could lead to performance issues. It would be nice to have access to a wide band O2 sensor in this case.

1978 KZ1000 A2 Click--->Build Thread
2004 ZX-10R
2007 Harley Sportster 1200
2020 Harley Street Glide Special
Angola, IN

Please Log in or Create an account to join the conversation.

More
29 Sep 2011 22:42 #480514 by WMKZ900
Replied by WMKZ900 on topic Do I have 76 carbs or hybrid carbs?
I tried closing off the mixture screws and ended up turning the air screws in to get an idle that was around 1.5k and still kind of rough. The air screws ended up being out only 3/4 of a turn.

The point that the tack is reading high is probably part of the issue that I had not considered.

My speedo reads 10 mph fast at 60 mph.

The mixture screws do have a sharp end and I see the potential of beaking and end off. They have orings that are old and brittle and that could be an issue.

According to the Clymer manual, the mixture screw carbs started in 77.
s
There listing for carb adjustment gives the turn out for the air screw carbs 73 through 76 and the adjustment for the mixture screw carbs from 77 on.

None of the specific carbs do they give you a adjustment for air screw and mixture screw on the same carb, yet mine has both.

Thanks for the advice.

Have and Running
66 Honda S90
71 Honda CB350
71 Kawasaki H1 500
73 Kawasaki H2 750
76 Kawasaki KZ900
06 Kawasaki Concours

Had
65 Honda S65
68 Honda CL 175
71 Honda CB 450
72 Kawasaki H2 750
74 Kawasaki H2 750

Please Log in or Create an account to join the conversation.

  • Motor Head
  • Offline
  • User
  • FIX UP YOUR BIKE RIGHT AND CHEAP
More
29 Sep 2011 22:53 #480516 by Motor Head
Replied by Motor Head on topic Do I have 76 carbs or hybrid carbs?
I'll toss in my .02c, I would try to set the Air Screws around 1 1/2 turns out, then see where the fuel screws make the Overall mixture Idle best.
It would be interesting to know how many turns the Air screws are at when the fuel screws are closed. I would think it wouldn't want to run well, Lean, with the Fuel Screws closed. Why there is a screw for each on your carbs, well it would be a guess but must be manufactured when the design was changing. Some engineer thought it would work with two adjustments. Bet he never saw a screw driver in his life, let alone a running set of carbs.

1982 KZ1000LTD K2 Vance & Hines 4-1 ACCEL COILS Added Vetter fairing & Bags. FOX Racing rear Shocks, Braced Swing-arm, Fork Brace, Progressive Fork Springs RT Gold Emulators, APE Valve Springs, 1166 Big Bore kit, RS34's, GPZ cams.
1980 KZ550LTD C1 Stock SOLD Miss it
1979 MAZDA RX7 in the works, 13B...

Please Log in or Create an account to join the conversation.

  • gd4now
  • Offline
  • User
  • Denco where did you go?
More
29 Sep 2011 23:00 #480520 by gd4now
Replied by gd4now on topic Do I have 76 carbs or hybrid carbs?
IIRC there were some Kz bikes that came with the carbs that have both a fuel and air adjustment screw. This is certainly a fact related to the kz650s, but they had the smaller vm24ss carbs.

I have read that all the Suziki bikes that came with vm26s had both types of adjuster screws. The pic that Patton posted is from a how to on the GS resource site. I am pretty sure that some of the larger KZs had them to.

At to settings I would set the fuel screw which are on the bottom of the carb turn these out 1 3/4 turns and leave them there. Then set the air screws which are on the side of the carb bodies about 1 3/8 turns from lightly seated. Then when you tune the pilot circut use the air screws only - the the fuel screws where you set them.

1977 KZ650 B1
Pods and Denco header


OLD KAW OWNERS SMILE ALOT

Please Log in or Create an account to join the conversation.

More
02 Oct 2011 23:48 #481083 by WMKZ900
Replied by WMKZ900 on topic Do I have 76 carbs or hybrid carbs?

gd4now wrote: IIRC there were some Kz bikes that came with the carbs that have both a fuel and air adjustment screw. This is certainly a fact related to the kz650s, but they had the smaller vm24ss carbs.

I have read that all the Suziki bikes that came with vm26s had both types of adjuster screws. The pic that Patton posted is from a how to on the GS resource site. I am pretty sure that some of the larger KZs had them to.

At to settings I would set the fuel screw which are on the bottom of the carb turn these out 1 3/4 turns and leave them there. Then set the air screws which are on the side of the carb bodies about 1 3/8 turns from lightly seated. Then when you tune the pilot circut use the air screws only - the the fuel screws where you set them.


gd4now,
I took your advice and adjusted the air screws and the fuel screws as suggested and it started and idles better than I can remember in the past few years.

Thanks

Have and Running
66 Honda S90
71 Honda CB350
71 Kawasaki H1 500
73 Kawasaki H2 750
76 Kawasaki KZ900
06 Kawasaki Concours

Had
65 Honda S65
68 Honda CL 175
71 Honda CB 450
72 Kawasaki H2 750
74 Kawasaki H2 750

Please Log in or Create an account to join the conversation.

Powered by Kunena Forum