Carburetion Suggestions for 810cc

does anybody have an actual formula for carb sizing per cc?ive got an automotive version somewhere that really suprised me,but it really gets you pretty close!

It really doesn't matter where the BS34's came from does it? I may have a line on a set from a 95 police.

Id run a set of 34mm Mikunis like is on my 82 GPZ750. They are plenty stout on that. A set of 29s is getting pretty pricey lately & ones for a 650 are hard to find. The carb spacing will be wrong on the police carbs

Well it'll be a 750 head, but aren't BS34's BS34's? I figured the spacing would always be the same.

The carb spacing will be wrong on the police carbs

Where do you get that from?
I know for a fact that GPz1100 throttle bodies have exactly the same carb spacing as the 750 fours (which is the same as the 650's), and the police models (82 on) use the J motor, and that has the same carb spacing as the 1100.

Short version:

The Police Mikuni BS34's have the same carb spacing as the 650/750 motors. You may have to use the J carb holders (manifolds), I'm unsure about that. Probably have to re-jet though.


If you have the bucks, I'd suggest getting a set of BS34 carbs from Wiredgeorge, wouldn't it just be so cool to be able to just bolt the carbs on, and not have to deal with them???

An Engineer eh?? What possible excuse can you have for not fuel injecting it??? :evil:



Tell Wiredgeorge he's old and over the hill and he might give you a discount :laugh:

Haha, i just bid on some throttle bodies from a gsxr today steell, might get them for very cheap, and then its modify modify modify. I dont have any excuses for not fuel injecting, which is why I will be if i can get some TB's for cheap, GPz1100's are too expensive. I even have an electromotive tec2 computer which would work great if i can find somewhere to put it.

I have a set of 1995 police carbs on the way soon, maybe, George said I'd need J manifolds to go with them and they'd go right on the old 750 head. The 95 carbs should be nice and clean, good floats etc. I'll use them while I'm developing the fuel injection/turbo system next summer! Although If I'm going at that I should put off buying high comp pistons when i could get the 810cc turbo pistons if i'm going that route. Definitely be over 100hp then!

You have to slot the mounting holes in the J manifolds to fit the 650/750 head.

It will take a little work to use the Turbo pistons in a non turbo motor, the Turbo wrist pins are larger.

Turbo rods will fit the non Turbo crank though, and there are a set on eBay right now

I think I have a new set of J manifolds around here somewhere, I'll look this weekend if I remember

You've got everything around there somewhere dont you steell?

Turbo rods eh? this build could get interesting if I'm not careful. Will I need new cams? Theres a voice in the back of my head telling me yes.

Edit: So I bid on the turbo rods, they wont be too expensive I dont think, is that all I need for engine internals to go turbo?

WHere do you put all the electrics steell? Theres not exactly a lot of room anywhere on a 650 for a computer.

You can put them where the airbox sits if you are not using an airbox and if your plennum isnt to big
And keep an eye on the current draw of all the electrical goodies as the 650 does not have a lot of spare power to play with