Best Carb for a 750??

I am currently running kehnin CV34's and am wondering if there is a better setup for the 750. Are the BS34's any better? I also seen flat slide 34's mentioned here, any thoughts would be appreciated.

I hav'nt heard of anything other than the CV34s or BS34s.............except, maybe, and memory is a bit hazy here..........did'nt someone..milkman or biquetoast put a single SU carb with a homemade manifold on one ?

I hear that flat slides are good.

Well there is always the earlier design (VM26's I believe). From experience I can tell you that the VM's deliver worse gas mileage but are otherwise just fine. Some people prefer them. They supposedly give better "throttle response" which is something that I never understood the meaning of anyway (to me there is just slow, fast, and faster but I don't know).

I would stick with CV carbs on a stocker. I'm interested to know if the mikuni/keihin CV carbs produce noticably different performance characteristics, but I doubt it.

Flatslides are prohibitively expensive but my understanding is that they are much much better. If you find a good deal on a set of flatslides that you can mount up to the 750 somehow I say go for it -- your performance will almost certainly improve.

Just my .02 worth.

Also, looking for the BS36 miks that where used on the GPZ750/elsewhere is not a bad idea. At least you know you can bolt them up with slight mods.

From stock form a 4-1 ex, pods, and maybe a port and polish etc might be a better route to go for better performance.

In other words,

Do some other engine mods before worrying about your carbs, they probably won't make a damn bit of difference (they are generally not the bottleneck on performance people seem to think they are in both our bikes and in the automotive world)

not really worried about making more power at the moment i was more thinking along the lines of ease of tunning. I'm really more interested in the mikuni/keihin CV type carbs.Thinking along the lines of which carb delivers better preformance stock.

My opinion, ease of tuning is the same with both carbs. For that matter, its pretty much the same for all 4 stroke engines. (2 strokes are a little picky)

Tuning is very simple. Just jump right into it. If you have a stocker then clean the hell out of the carbs (you can get a lot of info on this site), set the fuel height, synchronize, and then adjust the pilot jet.

Its not as hard as it sounds, take a weekend and do it. There is TONS of info on this site as to how to do this. Be careful with the small parts and make sure that you put the carb back together with everything thats supposed to be in it!

Not a bad time to make sure that the carb-head boots are good.

ok i guess you think i'm noob...but i've done all this before. Over the winter i personaly did a complete top end rebuild and cleaned the carbs,but my issue is that the carbs are clean but they don't run right on cold day start ups. Where i'm from its cold alot lol i just find these carbs finicky. The do however run better than ever once warm.

I dont know the work you did on your carbs but if the floats are set low or a little off it will be hard to start when the engine is cold. Remember the higher the float level the easier it is forthe engine to sigfen fuel from the carbs.

I just set the float height on my carbs three days ago and the engine has more power then it ever has had in the past. If I power shift second gear the front wheel will come off the ground an inch or two. If I let off and snap the throttle hard when rolling it will carry the front tire 10or13 feet. :woohoo:

Also my engine showed tan colored plugs wich means a little lean. after setting the float when I look at the plugs they are black around the edge and the center electrode is white and these were the same plugs I had before the float height change.

Now when I start it in the morning it take two or three kicks, before setting the floats I would kick it till I started to run out of energy.

Frank wrote:

.....Where i'm from its cold alot lol i just find these carbs finicky. The do however run better than ever once warm.

It can be cold here also :laugh: I like my Keihin CV34s. Cold day starting can take maybe 2 prods on the starter button and it can take a couple of minutes to warm up but I think thats just the nature of the beast.
The only thing I do with them is clean them out every winter. I put them back on the bike in March, primed them and with one hit on the buttin she started !

I wasn't going to say anything since the original post was just a question as to preference. Either the CV34 or BS34 will work great if they have been cleaned, tuned and are jetted appropriately. The only downside to the CV34 is that main jets and slow jets are almost impossible to find so if you have made any airbox or pipe modification which has leaned the air/fuel mixture, it is a tad more difficult to rectify the situation. The BS34 has all tuning parts readily available.

OK... later in the thread the actual question/problem came out:
"ok i guess you think i'm noob...but i've done all this before. Over the winter i personaly did a complete top end rebuild and cleaned the carbs,but my issue is that the carbs are clean but they don't run right on cold day start ups. Where i'm from its cold alot lol i just find these carbs finicky. The do however run better than ever once warm."

The carbs don't allow easy starting and are "finicky" in the cold. OK... this CAN be addressed. You didn't mention airbox/pipe changes. Have there been any? If so, you need to do some rejetting within the constraints of parts availability. If there have been no airbox/pipe mods, then your cleaning job was a tad inadequate. I hate cleaning slow jets but in this case, I strongly suggest you take them out and soak them in carb dip and then run a fine wire through them. Blow spray carb cleaner through them and observe the pattern of spray coming out... it should be fairly tight and not come out in a splatter. If it does, you will be forced to try and find some of those #35 pilots (slow jet) which are going to be hard to find. Deposits can get on the inside of the jet making fuel atomization a mess. There is also an airjet on the intake venturi edge... plug the pilot jet well and the mixture screw well and blow carb cleaner into the jet and ensure you see finely atomized spray coming out the hole in the other end of the carb in the venturi. Last, make sure that the choke butterflies shut cleanly. It isn't unusual for the butterflies to remain cracked open a tad if the rack has been split. The CV34 carbs ARE FUSSY about being split as the return spring for the 3 and 4 carbs is miserably weak. BTW: If you find your pilot jets have deposits and need to be replaced, you could try and find the correct drill bit and drill them out to become #38 pilots... the bike will start a whole lot easier.

Last point... if the carbs don't run great on cold days, the probable cause is that the cold mixture is a shade lean... the best cure is to use a tad larger main jet... this is the barrel shaped jet. I think your later 700 will have a #68 main? Just go up one size and this will really help... perhaps to a #70. If it has a #70, go to a #72. The jet needle/needle jet combo on the later CV34 is far richer than on the earlier versions so a little bump in main jet size (this is where the main jet operates on this carb) is helpful... for those not understanding the CV34, the main jet really isn't a main jet... the secondary main jet is really the main jet.

Ok well this post turned into a mess sorry about that i guess its my fault. Starting cold is actually not a problem at all. It starts fine but once started it is hard to get it to idle. Full choke bogs it and kills it if your don't rev it. Once givin some throtle it will hold a 3500 full choke rev then slowly bog again. So my prblem i guess is that i have to really mess with the choke to keep it idleing when cold. The temps this happens are from anywhere under 15 degrees celcius or so. When the weather is like it is now here 20+ it starts fine with alittle choke. I did clean all my jet in the way wiredgeorge suggested and they are all flowing freely. It could just be this bike, it is my first kawi and i'm used to hondas which never seemed to mind the cold.