Carbohydrates

[Royalratch]

So the final piece of my power puzzle is carbs - which I'm now on the lookout for.

We've had the discussion on here before about CV versus Flatslide. I'm an amateur in the carb world but understand from a bit of research and some members on here that Flatslides are easier to set up but not as smooth as CV carbs at low revs / speed - but then CVs are fiddley and temperamental.


wiredgeorge.com has this to say about the issue:

WHY CONSTANT VELOCITY CARBURETORS?

Most KZ and Z owners are looking for ways to bump up the performance of their bikes.

If you keep an eye on aftermarket carburetor options, you quickly discern that older VM29 and VM33 smoothbore carburetors and modern Mikuni RA Flatslides cost dearly and the prices continue to rise.

A less expensive and perhaps just as effective option is the use of refurbished Constant Velocity carburetors. Both Keihin and Mikuni manufactured this variety of carburetor.

WHICH CARBURETORS TO USE?

As noted, there are choices. The Keihin CVK34 or CV34 are used on KZ750 models. A drawback of the Keihin CV series is that some parts are unavailable (slow jets in particular). The Mikuni BS32/34 family has better parts availability. wiredgeorge Motorcycle Carburetors recommends and sells the more readily available BS34 assembly which works great in almost all applications.


I guess my question is, what is the best carb type AND size for power / rideability for an mildly tuned 810cc motor?

Bigger carbs obviosuly mean more power but too big is bad for low speed manners. Is he ballpark for my set up 29mm - 34mm?

[Pigford]

Heres an example:

http://www.mikunipower.com/RS01.htm

RS34 would be good

[skibs]

didn"t the early 750 gixers have a cheaper version of the rs?
vms/vss or something.seem to recall they were 29mm.i might be wrong,pretty sure 34mm gixers were cv

[steve.w]

my 810 unitrak ran the standard mikunis (larger mains) standard airbox and it was sweet as a nut and the throttle response was crisp

[Royalratch]

I think that's the exact setup recommended by Pigford and wiredgeorge - tweaked out BS34's.

[Pigford]

I think that's the exact setup recommended by Pigford and wiredgeorge - tweaked out BS34's.

Weren't me with the BS34's - I hate CV's with a vengance - PITA to tune as they erally need the airbox to work properly

I just sold some Slabside 30mm Mik's - they are commonly bored out to 34mm for the race bikes

[Crofty]

I would also stay away from cv carbs and have heard what steve.w says that any normal slide carb from 26 to 29mm work really well. Also Big green Bus and someone else (forgotten name) say that the flatslides from Suzukis (poss 29mm ish) also make the 810 motors go like stink. Just not sure about the odd angle of the float bowl and I think someone onhere said they have trouble setting them up 100%, though BGB said he made some adapters to level them up on his.
Just to add, I know aguy in the US that has run bigger than 810cc and swears blind the VM26mm correctly jetted gives adequate performance and no nasty flatspots.
I would love a set of Keihin CR29mm's on mine when its done.

[Royalratch]

Crofty! That's another set of carbs in the mix!

I think I want to go for BS34's or VM29 Smoothbores. After much reserach from all it seems to come down to about these 2.

wiredgeorge make a custom version of the VM he says is like a 30mm - best of both worlds.

Either way, I just need a bolt on set that are good as new and already set up as carbs are a bit of a mystery to me.

I also need them in black.

[kev edwards]

Use whatever carbs you want, i have had bikes with all sorts of carbs on and if you get them tuned on a dyno they should be fine, as you are not going for flat out performance standard carbs of all the above should be fine.