Help me decide

We need nads to chime in on this thread!!!

T_Dub wrote: The 810 kit is a 10.25:1 CR. Unless he had his head decked. The cams "loading up" is a weird thing for sure.

Anyways, the point of this thread was to help me decide what carbs. I've decided I'm gonna buy a set of RS34's from Schnitz Racing, as they are the cheapest. My good friend who knows more about big 650's than anyone I know says that Mikuni themselves admitted that the needles are for racing 750's. I bet they'll work real well. I'll report back about it in a month or so.

Can't wait! :woohoo:

Great! Personally I think this bike is a bit hardcore to be putting stock KZ1000 carbs on it. If I wanted a cruising bike I wouldn't have built it. I want a high RPM screamer. Why would I have paid over $1000 on a free flowing head built with the best components if I wasn't going to rev the shit out of it.

RS34's will make this bike howl. The throttle response will be snappy, and the revs wont drop until I haul back on the throttle. I fully intend to get this bike on a track at least once a year, and the only time it will see the open highway is for the relay ride. I hate highway riding.

In an ideal world you would try a few different carbs...

I wouldn't recommend RS34's on an engine that small. Most times you need at least 1100cc to warrant a set of RS34's. They will be sluggish under 5000rpm. I wouldn't even put them on Z1 unless it's punched out over 1075cc.

CR29's or VM29's will feed the engine perfectly all through the rev range. They will work well on engines up to 1100cc - over that they are a little small.

Black, the engine would not idle once it was warmed up the farther one rode the worse it got. I tryed the advance curve stock, advanced 5 degrees, messed with that a lot. The cams were dialed in within 1/2 degree according to what the cam card stated; the compression may have been the only factor that was in question as the engine was not new.I tryed several idle jets as well, from the leanest I could buy to way to rich. All I know is it runs good now, and even with the web cams it ran well til it warmed up. I think the .400 lift cams were a bit much for my 810 engine.

Godfrey wrote: Black, the engine would not idle once it was warmed up the farther one rode the worse it got. I tryed the advance curve stock, advanced 5 degrees, messed with that a lot. The cams were dialed in within 1/2 degree according to what the cam card stated; the compression may have been the only factor that was in question as the engine was not new.I tryed several idle jets as well, from the leanest I could buy to way to rich. All I know is it runs good now, and even with the web cams it ran well til it warmed up. I think the .400 lift cams were a bit much for my 810 engine.

Insufficient valve clearances can cause these symptoms.

Good Fortune!

les holt wrote: My experience, again, my experience is with smoothebores is the 29's are absolutely the smoothest through the entire range of any carb I have ran, from idle up, even on an almost stock 750. The 33's run GOOD! but you have to be awake when you have them, they will bog if not in a sweet spot. 33's don't have the greatest street manors but the 29's do. Like I said, my experience!

Les Holt

I have to agree with what Les has to say here. I have had VM26's and VM29's on my KZ1000 and the 29's are the all around better carb, hands down. I also had a Suzuki 750 with BS32's and they were a pain in the ass. I have a tendancy to agree with the bias against the BS. That bike even had the stock airbox and stock exhaust, and boy was it tough to deal with when cold.

Godfrey wrote: Ok I'm gonna chime in here, not sure what cams you are gonna run in that 810, I spent most of last summer tryin to make some RS34s work on my 810 with 118 web cams, thought it was a carb problem, turns out the engine got warm and the cams were loadin up and foulin the plugs. I put stock 650 cams in the engine and the rs 34s run just fine.


Godfrey

That last line confirms the 34's work on a small engine... the listed application from Mikuni is 600 to 750cc motors and they come jetted accordingly.

Godfrey does not mention any level of porting on his head, so I assume when he bolted in a set of .400" lift long duration cams on a stock head his small stock ports could not support enough air flow to make the extra lift and duration any use for his motor... in fact it made it run poorly... going back to the stock cams tightened up the timing increasing useable compression which his large carbs seemed to need.

I think it all boils down to picking the correct parts that complement each other... once you deviate away from an engineered stock motor performance can either go up or in some cases down but it all depends on the correct combo.

Again, I'm no expert, and real life experience should count more than my dribble. The reason I've read is that since smoothbores have less venturi effect (in order to flow more) their metering signals are a tad weak at low rpm.

Regardless, if you type "smoothbores" into this page you'll find something of interest, I reckon, from pure love for the things to suggestion you run Gixxer CV carbs. 209.85.117.197/12415/11/0/p1019623/Z1Z90...ical_posts_2002A.pdf

DoubleDub wrote:

T_Dub wrote: Guess they don't know about wiredgeorges website haha.

The CR29's are going to be the ticket I think. Or I can just stick with the BS34's for now and save $800.

I've never fully understood why larger CV type carbs are used where smaller manual slide type carbs are used.

I thought I commented on this post but I couldn't find it.
The difference is that you have a vacuum operated slide that very rarely stays in the W/O position, if at all. The next thing you have to take into account is the throttle shaft and the throttle plate that restrict the overall volume of the throat of the carb. So even though the throat is larger, the 34s may not flow as much as the 29s do because of the restrictive throttle plate assembly. Does that make sense?
A flow comparison would be cool.

the reasons blackz1r stated are the same reasons that harley davidson was able to use the 40mm keihin cv carbs on everything from 500cc singles,through the entire sportster range and up into the big twin's until they went fuel injection.

so from 500cc to 1500cc.

the engines vacuum allows the cv carb to only open the slide (therefore get as much air)as much as needed to for that particular throttle opening.

leon

Yes it does - and it would be cool if someone flow tested all of these and then provided the info...guess we better pool our funds for a flowbench... :whistle: