VM 29's gpz 750.

So I picked up some VM 29's to run on my
83 gpz 750 motor with an old Kerker and some pods'

IIRC they have 122.5 mains
06 needle jet
117.5 pilot jet
Would this be a good place to start tuning them.

Dave,

I think the mains are a little too big for your 750. I would say 120 mains are a good starting point for a 1000 or larger bike. For your GPZ I might suggest 115 as a starting point.

The pilot may well be fine, but that is dependent upon which set of 29s you have. To my knowledge that were at least 3 versions the A2, A7 and A12. The A12s came with a larger cutaway on the slide than the other 2 did (2.0 vrs 1.5) and may require a larger pilot jet to help overcome the additional air the larger cutaway allows at idle and low throttle.

The air screws on 29s don't behave the same way as on other VM series carbs. This is because of the hole in the screw towards the tip. 1/8 turn out is about right for #17 pilot jets.

Here are some suggestions from Z1 on jetting for 29s you may find of interest - note that they have much smaller main and pilot jets noted for the 650s.

29mm smoothbores Z1 / KZ900 / KZ1000
Main Jet 120
Air Jet 0.9
Needle Jet O-6
Jet Needle 5DL31-3
Throttle valve (slide) 1.5mm cutaway
Pilot Jet 17.5 or 20.0 (or 25 in the later versions)
Air Screw setting 1 1/2 turns out

29mm smoothbores CB750
Main Jet 115
Air Jet 0.9
Needle Jet O-6
Jet Needle 5DL31-3
Throttle valve (slide) 1.5mm cutaway
Pilot Jet 17.5 or 20.0 (or 25 in the later versions)
Air Screw setting 1 1/2 turns out

29mm smoothbores KZ650
Main Jet 105
Air Jet 0.9
Needle Jet O-4
Jet Needle 5DL31-3
Throttle valve (slide) 1.5mm cutaway
Pilot Jet 15

There are also suggestions for jetting the 29s on the Sudco site - but I think they are somewhat on the big side esp for the pilots.

Model Main Air Pilot Needle Float Height Throttle Valve
Honda CB750 (SOHC) -1978 VM29-A2 #115 .9 #17.5 #5DL31-3 0-8 23mm 1.5
Kawasaki KZ650 (77-79) VM29-A7 #120 .9 #25 #5DL31-3 0-6 23mm 1.5
Kawasaki KZ900 (76-77) VM29-A7 #120 .9 #25 #5DL31-3 0-6 23mm 1.5
Kawasaki KZ1000 (77-80) VM29-A7 #120 .9 #25 #5DL31-3 0-6 23mm 1.5
Suzuki GS750 2-Valve (77-79) VM29-A12 #115 .9 #25 #5DL31-3 0-6 23mm 2.0
Suzuki GS1000 2-Valve (78-79) VM29-A12 #115 .9 #25 #5DL31-3 0-6 23mm 2.0

GD4NOW these have the 1.5 cutaway.
I believe the needles are the 5DL31-3.
I did read the Z1 deal and was thinking the
cb set up would be close.

Will be ordering kit's, jets and intake's Monday
so I'll see what comes in them and
order according to that

They did clean up nice though.

Agreed! What was the cost on an ultrasonic cleaning?

FREE.
We just got a small unit at work
But it's not long enough for a full rack of 4 carbs.

Few hours in the cleaner then a lite going over in the
glass bead cabinet then going back in the cleaner in the morning.

Called Robert at Z1 this morning and ordered carb parts
and new intakes to fit the 29's.

Also ordered a few jet size's
115, 117.5 and 120's.
With the 122.5 I have I should
be good.

Got the carbs cleaned up.
Love that new ultrasonic cleaner at work.

KZ 900 intakes. Had to slot the bolt holes to fit
but they are a perfect match for the Gpz ports
so no need to gasket match the ports.

Mounted up with new intakes.

Rest of the story.
Started with 117 mains and think it's running lean.
Idle I get little responce from the air screw's
and off idle to lower mid range suck's.
1/2 throttle up seems to be close so after dinner
I'm gunna check float level again ans see were the needles are set.
New plugs after a 30 mile city/hiway ride.

I am currently building almost exactly the same bike 78 KZ with an 83 Gpz750 engine.As I am usung the same carb set up Iwould love to hear what you fianlly settled on for setting up the 29's.

Thanks
Kevin

Hey Dave I'm running 122.5 mains and I think 115 pilots, been a long time sience I looked and with stacks no pods. You'd be suprixed how much gas these hot 659's can take.
Mark

gd4now wrote: Dave,

I think the mains are a little too big for your 750. I would say 120 mains are a good starting point for a 1000 or larger bike. For your GPZ I might suggest 115 as a starting point.

The pilot may well be fine, but that is dependent upon which set of 29s you have. To my knowledge that were at least 3 versions the A2, A7 and A12. The A12s came with a larger cutaway on the slide than the other 2 did (2.0 vrs 1.5) and may require a larger pilot jet to help overcome the additional air the larger cutaway allows at idle and low throttle.

The air screws on 29s don't behave the same way as on other VM series carbs. This is because of the hole in the screw towards the tip. 1/8 turn out is about right for #17 pilot jets.

Here are some suggestions from Z1 on jetting for 29s you may find of interest - note that they have much smaller main and pilot jets noted for the 650s.

29mm smoothbores Z1 / KZ900 / KZ1000
Main Jet 120
Air Jet 0.9
Needle Jet O-6
Jet Needle 5DL31-3
Throttle valve (slide) 1.5mm cutaway
Pilot Jet 17.5 or 20.0 (or 25 in the later versions)
Air Screw setting 1 1/2 turns out

29mm smoothbores CB750
Main Jet 115
Air Jet 0.9
Needle Jet O-6
Jet Needle 5DL31-3
Throttle valve (slide) 1.5mm cutaway
Pilot Jet 17.5 or 20.0 (or 25 in the later versions)
Air Screw setting 1 1/2 turns out

29mm smoothbores KZ650
Main Jet 105
Air Jet 0.9
Needle Jet O-4
Jet Needle 5DL31-3
Throttle valve (slide) 1.5mm cutaway
Pilot Jet 15

There are also suggestions for jetting the 29s on the Sudco site - but I think they are somewhat on the big side esp for the pilots.

Model Main Air Pilot Needle Float Height Throttle Valve
Honda CB750 (SOHC) -1978 VM29-A2 #115 .9 #17.5 #5DL31-3 0-8 23mm 1.5
Kawasaki KZ650 (77-79) VM29-A7 #120 .9 #25 #5DL31-3 0-6 23mm 1.5
Kawasaki KZ900 (76-77) VM29-A7 #120 .9 #25 #5DL31-3 0-6 23mm 1.5
Kawasaki KZ1000 (77-80) VM29-A7 #120 .9 #25 #5DL31-3 0-6 23mm 1.5
Suzuki GS750 2-Valve (77-79) VM29-A12 #115 .9 #25 #5DL31-3 0-6 23mm 2.0
Suzuki GS1000 2-Valve (78-79) VM29-A12 #115 .9 #25 #5DL31-3 0-6 23mm 2.0

exactly, my 34mm keihins have 130's in them for my 750. might need to get the carb holders also.