TOPIC:

My 29s have the same bowl, the square on #4, measure just over 29mm (close to 1.170) and have chrome slides and the plugs on the bottom.... bought em new in 83 from Racecrafters. Lucky you they are worth some big $.

My 29s have the same bowl too.

Alright, in addition to the confirmation from you fine folks, I did indeed find that little detail on #4. I guess this was the mother of all spare part throw-ins, since it seems to be worth about what I paid for the bike.



The question now is which carbs I should use. I'm still thinking I'll stick with the stock set since I'm just looking for a solid, serviceable ride around town. Would the 29's make a big difference on an '81 KZ650? It also seems like they'd interfere with the petcock since there's very little clearance there above the stock carbs.

What do you guys think?

Thanks, again.

Barry

Overkill on a stock KZ650. The engine won't be able to take advantage of the carbs' flow capacity. You will end up jetting them down so much they won't really be running as they could if on a larger engine. If I had them I would sell them since they would being some cash that could be put to better use. Ed

Sense the mystery has been solved can I ask a could carb related questions. Can someone post a quick description of the different types of card. I.E. what is VM. What is smooth bore, what is VMSS I know this can get very in depth really easy but I hear all the terms and have no idea what they mean.
RS?
VMSC?
Square bore?
Smooth bore?
RS flat slide?
They list seam endless. Maybe a new posting would be better?

650ed wrote: Overkill on a stock KZ650. The engine won't be able to take advantage of the carbs' flow capacity. You will end up jetting them down so much they won't really be running as they could if on a larger engine. If I had them I would sell them since they would being some cash that could be put to better use. Ed

Thanks, Ed. Your advice settles it for me. I will do just that.

Barry

The carbs ran good on mine (when stock) but always had that little hick up just off idle they are known for..... probably not much power diff and like Ed says on a stock motor probably a little over kill......... I always planned on the 831cc MTC piston kit with cams (where they would really shine) but ran outta time and cash too.

Still going back and forth on what I'm gonna do to as the stock carbs are running very good and are smoother down low. You would need Z900 manifolds to fit em...... need to slot the holes slightly too to bolt em up but with a round file it works out pretty easy and the head matches up perfect. Between Jets are us and Z1 most parts are around but not all and are drying up.

Ed to get the smoothie's to idle right on a small motor you need to go to a REAL big pilot jet.
Sudco list a 25 pilot and a 125 main as a starting point for a 750 cc motor.
On a small motor the idle signal is so weak without a big pilot they will not pull fuel.
I've got 22.5's in mine on my 810 cc GPZ motor and it idle's like shit. Pull the baffle and it will not idle under 1600 rpm's.
Another jetting step with the VM29's is the replace idle air jet's which I think going up on them will help
my idle issue.

Mikaw wrote: Sense the mystery has been solved can I ask a could carb related questions. Can someone post a quick description of the different types of card. I.E. what is VM. What is smooth bore, what is VMSS I know this can get very in depth really easy but I hear all the terms and have no idea what they mean.
RS?
VMSC?
Square bore?
Smooth bore?
RS flat slide?
They list seam endless. Maybe a new posting would be better?

RS = Mikuni flat slide carbs. These are modern mechanical slide carbs
VM = Mikuni round slide, smooth bore , mechanical slide carbs. No throttle valve. Factory installed on Kawaskis in the 1960s and 1970s.
29 smooth bores = high performance aftermarket VM carbs.
CV carbs = carbs with vacuum operated slides and cable operated throttle plates . Used on modern bikes until replaced by fuel injection.

With those bigger carbs, shouldn't he be wondering if someone installed bigger pistons or something?
At the least I would check the cylinder block to see if it says 652 or 738.

martin_csr wrote: With those bigger carbs, shouldn't he be wondering if someone installed bigger pistons or something?
At the least I would check the cylinder block to see if it says 652 or 738.

Martin, you read my mind. I was starting to wonder all of this since the previous owner said the 29s were on the bike when he got it. Maybe this is why it isn't running with the stock carbs now.

Tell me where to look and what to look for and I'll do it.

Thanks,

Barry

Left hand side of the engine at the base of the cylinder block, directly above the generator cover.
A 650 will have 0.652 L cast into it. the 750-4 is 0.738 L. pretty sure.
There's other stuff to check, but the block is the easiest.

A 650 block could have a wiseco 700 kit. A 750-4 could have an 810 kit.
I don't know if a 650 block can be resleeved for 750 pistons or an 810 kit.
The simplest & cheapest thing for someone to have done would be to install the 750-4 stuff.