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Hi, I have a 77 kz650 that is getting the kz750 jugs bolted on, with a wiseco 810cc kit. Still using the 650 head for the higher compression/more power. What should I use for carbs? I assume that the stock 650 carbs are too small (I think that they are 24 or 26mm) I have heard that mikuni 29mm smoothbores work well, any thoughts? Also, I'll probly get a set of carbs from ebay, and from what I have seen on there, they usually just say what bike they are for. Should I be looking for carbs off of a stock kz900 or 1000? I'm pretty new to all of this stuff, this is my first bike/engine build, so any help would be greatly appreciated. thx

Im not looking for full power potential (sad but true) but my 24s have been working fine on my 750 if that helps at all.

I'm looking for as much power as I can get. I want to drag it occasionally on weekends, and faster is better:) .

If you engine is unmodified, other than using stock 750 parts, the VM24 carburetors from your 650 should work fine. If you go with VM26/28/29 carburetors, you will raise the point in the rpm band where peak power is made but your low end will suffer. The VM29 carburetors help a lot on a highly modified engine that requires more gas. I test VM24 carburetors on a stock KZ900 and they work great; especially at the low end.

It's getting the wiseco 810cc kit, possibly bigger cams, it also has a MAC 4-1 pipe, and pods. Is this enough to require bigger carbs?

10 years ago I ran an 80 ltd 750. I used pistons, a heavily ported head and cams from an 84 gpz, v&h pipe with 29 smooths. I had this bike stretched 5" and used the ltd's 16" wheel. This bike very quick and fun to ride. Bike was docile in town. Very easy to drive. That's the one I wish I had back.
Les Holt

Seems your goal is to make top end horsepower... in this case, the carb venturi size should go up from the stock VM24... a VM26 won't make a lot of difference but a VM28/VM29 might help you get there a bit faster. The VM29s are expensive so you might want to try some BS series CV carbs. BS32 carbs work great on a stock KZ900 while BS34 carbs work well on modified 900/1000s. I suspect some BS34s would be a good choice for use with higher compression and cams. Use a quality petcock and larger fuel line.

Also any carbs bigger than 24mm have aprox 3mm bigger diameter inlets that have to be slid onto your boots. Very hard to force the larger carbs onto stock 650 boots.

Thanks for the input guys:) I'll have to keep an eye on ebay this winter.