What Carb is this (and how to get them working)

Hi Guys,

I am a complete newbie, just bought a 1980 Z750 two weeks ago.
It started bad but after startup it ran fine. When hot starting was no issue at all.

But since the first testdrive she doesn't want to start at all. She runs on brake cleaner and the like. got spark everything. Took the carbs partially apart and sprayed them with carb cleaner and blew them out with air. (to no avail)

To go further in the carb I would like to have a manual or something but I do not know the type. They are not the stock ones I think.

Here's a picture:





Another member told me to clean the pilot system but where is it on these carbs? :dry:
Any other help is greatly appreciated, the weather is nice so I would like to take her out for a spin

No eBay APP ID and/or Cert ID defined in Kunena configurationThose look like the OE Keihins that came with the bike. The factory Kawasaki manual will have a complete brakedown of these carbs.

Hi Otakar,

If you click the picture you can see Mikuni on the side.
The carbs in the workshop manual look different especially the choke etc.

I would suspect the pilot jets or choke circut are plugged with varnish. Have you tried sea foam?

The pilots jets are probably covered with a alunimum plug. They should be located next to the big jet. Roy

Yes, the GPZ had Mikunis the others had Keihins. The same was true of the KZ1000. On the 750 there were actually three different carbs used. It would help if we knew which model you have. This way a quick look in the book could make things easy. At this point we are just guessing. Since no other bike had the same carburetor spacing as the KZ650/750/900/1000/1100 it would be difficult to mount carbs from other bikes without major modifications. Since these are CV carbs they are an OE item. Have you removed the float boles to check for crud which could clog all the jets?

What throws me for a curve is that you say that the bike is a 1980, yet the carbs are black but should be silver and have dual angle cast aluminum diaphragm covers and they should be stamped steel or single angle aluminum.

On closer examination those look like they came off of an 83-88 GPZ750 (zx750 A1-A5) or a 82 Z750-R1 which was not available in the US. In which case they would just be a late version of the Mikuni BS34s

looking on another thread I noticed that the bike is an 750-E1 and that you are in Holland. Tis means that the carburetors can come from any of the bikes I listed but would be the BS34s 82-88 models.

You are the greatest

You found all the pieces of the puzzle while I was out running (have to stay in shape )

To back up your story:


Yes it is a european bike. Sorry that I forgot to mention this...

Some extra pics of the carbs:





Doesn't seem to much dirt in them? I have cleaned this out yesterday with Wurth Carb cleaner and also pulled out the choke and blew carb cleaner in there and blew it out with the airgun. Is the pilot system the screw in front of the choke system?

Just checked the Z1000 R1 parts list and yes, that are my carbs. Thanks Otakar!

Will take them apart again and do some more cleaning. But as I also have a trackday this week with my Ducati it might take a few days before I get to it

Flip them around and check the float boles. That is where all the MUCK would be. The top is only a vacuum chamber. Your bike originally came with the CV34 Keihins. These BS34 Mikunis are much superior to the Keihins.

Float boles have also been cleaned yesterday, were already as clean as a whistle.
I expected a lot of dirt there, but I only found a tiny bit of VERY fine brownish dust (probably rust from tank)

Could be that the former owner (who was a bit of a trader of old bikes) cleaned also the obvious parts but not the difficult parts (i.e. Pilot circuit etc.)

Good to know that the Mikuni's are better then the Keihin's. Now I have to get them working