Carb recomendations for a 1980 KZ550C w/ mild mods

I'm currently working on my 550c, just extended the swingarm 7", will be doing mild head porting, already have pods, also thinking about replacing the back half of the exhaust with a pair of stock GS1100 megaphones I have lying around. I currently have the stock TK carbs, freshly rebuilt with 92 main jets. I know I need bigger main jets, but am having trouble finding them. Here are a few questions, any suggestions would be appreciated.

1. will small mikuni or keihn main jets fit the TK carbs ?

2. would I be better off going with some CV carbs off of a later 550?

3. would I be better off finding some VM26's off of a 650?



Sarge

If you upgrade the mains to 94, you'll have a set of 81 GPZ Kz550D carbs, but in silver instead of black.

The ports are smaller on the Kz550C and Kz550D head than the heads with the CV carbs. The carb manifold bolt spacing is narrower as well. The carb spacing is the same center-to-center for TK22 and the CV TK26 carbs (from 82-83 gpz Kz550H), though, so it may not be impossible, but it would be a lot of work. Why not just throw in a used 82-83 gpz550 motor? You'd have virtually no work to do, it would be plumbed for an oil cooler, and will bolt right in. Then you can use the TK26 carbs. And it's not difficult to put the TK22 carbs on the TK26 carbed motors if you don't want to get new carbs right away. (It's only difficult to put TK26 carbs on the TK22 carbed motors.) There was a bunch of gpz550 motors on ebay just a little while ago in the $100 to $200 range. I suppose buying motors on ebay can be scary if there's no guarantee on it, though.

You'd be better off with TK26's rather than VM26's since the TK's will already have the right center-to-center spacing.

In my opinion, I would stick with the TK22's for simplicity of tuning and least hassle fitting to the existing motor.

I drill my own jets, and you're right, it's not easy to find some 94 jets. Keihin has a type of jet that will work, but not Mikuni. Or you can get the Dynojet kit which comes with 98, 102, 108, and 112 mains, but it's a $100. Drilling them yourself is very easy, plus if you mess up, the rebuild kits come with new 92's. The cheap drill at Menards have a chuck that closes all the way down to zero, and there are many sources for small bits online. The jet size is in hundredths of a millimeter as the diameter of the orifice.

It would be difficult to modify VM26 carburetors. Use the constant velocity Tekei carbs off a later 550... all you need to do is elongate the holes for mounting the carb holders. You will also need to use some larger Keihin main jets as larger Tekei main jets are not easily found.

Thanks WG, I figured that the VM26's would be a pain to make fit. Which keihn jets would fit my TK22's ? I might upgrade to TK26's later, but kinda steapped for cash right now.

Sarge

The TK27 Carbs from the GPz550/ZX550 '84-'86 should bolt in place of the TK26's. Remember if switching carbs, then you're going to need a different throttle setup and cables as well.

Small headed Keihin main jets that work in the CV and CVK series carbs are direct fit for the Tekei and the sizes seem to match well... in other words, a 100 Tekei main seems to be the same as a Keihin 100 main. The size and pitch of the thread are the same. Mikuni is different size/pitch so they won't work.

cool, thanks WG


Sarge