Choosing carbs for a ZX9 motor

Hello,

I am fairly new here and am seeking info from any motor building guru's that can tell me the pros and cons to different carb setups I am considering for a 1997 zx9 motor I am swapping into my 2000 ZX7R. I can choose from either the stock carbs from my ZX7, a set of stock carbs from a ZX9, or from a set of Keihin FCR 39mm or 41mm flatslides. I have access to each except the 41mm ones, those will be pricey and hard to find used. Please make your suggestions, what the gains will be and reasons you chose them over the others. Thank you in advance.

The stock Zx9r carbs are 40 mm keihins and seemed to work well with the stock zx9r. Unless you have modified the heads or are planning on more radical cams I would start with the stock carbs then go from there.

Thanks for the reply. I guess I forgot to add the info that the motor has supposedly had a big bore kit installed. The guy I bought it from has the 39mm flatslides to go with it but I thought he was a bit high on the price until I started looking into it more. As far as stock carbs go, are there differences in the model years of motors that the carbs will fit? I am having a hard time finding any for a 94-97 model year but there are a lot out there for 98-02 or something like that. Are they interchangeable? I know they were different motors but unsure if the carbs were different.

From the Haynes manual...

E series had CVRD40 and B, C and F had CVKD40. The ZX7 had CVKD38.

Thanks for the info but without having a manual, I don't know what years the corresponding series are and most people listing them for sale don't include the series, just the year of the bike they were taken off. Also, I now know that the E series used different carbs on them from the B, C, and F (what happened to D?) but does that mean that the E series carbs won't fit and work on a B, C, or F motor or does that mean that Kawasaki just tried something different for that year? Also, was it better or worse?

I've got a set of 39mm flatsides to put on my '98 (C series) ZX9R when I actually get the time and funds (going to use a pressurised air box as well). I emailed Factory Pro when I saw some 41mm for sale and and there response was (I don't know how a big bore kit would affect it):

41's suggested - but, still, 39 vs 41, it's still only a few hp.
Don't expect the 41's to make a lot more hp -
Slightly "not enough carb" only hurts power a little bit.
Power curves, 39 vs 41, 39's pull full throttle earlier than 41's

It's a bit difficult to match years to models as some models come out towards the end of the year...my F2 (03 model) was made in late 2002.
generally...
B = 1994 - 97
C1 = 1998
C2 = 1999
E1 = 2000
E2 = 2001
F1 = 2002
F2 = 2003

Not sure about the D series but I have an electronic copy of Kawasaki service manual dated Sept 1997 and this shows the C1 as US and the D1 as European but in other parts shows specs as the D1 being German and Swiss so not sure

There are a set of carbs on ebay atm item no. 120568453742

Hope this is some help. If you want a copy of the manual that I have PM me.

Check this site, most who have done the engine change are using 39 flatslides.
http://homepage.ntlworld.com/webzxr/zxr750r/

Thanks everyone,

I think I have decided to go with the 39mm flatslides. Now if I can find the number to the guy that had them. Can't wait to complete the swap. Once that is done right, it's off to finding new suspension bits and light weight wheels!

As this is a new motor for you, you could still go for the stockers. The increase in bore will cause an increase in air flow but I'm assuming that you went to 998 cc, or what ever it is and they should still work fairly ok. I would start with the cheapest way for right now and go from there. The zx7 carbs would definitly be too small however. The web site that madkaw posted says 39mm flatsides and that may be a good choice also. I find making just a few mods at one time eliminates a lot of trouble shooting if it runs bonkers when first started. Also if you start with after market carbs you will have no comparison to what it was stock, (with the big bore kit of course). Have a JB with a brew and all will become lovely.

I may be wrong but I thought the carb spacing was totally different after the B model as the B model is basically just a bigbore zxr750. All later model 9's were a totaly new engine design and I thought one of the new features was closer cylinder spacings. In any case I am currently finishing off a zxr750 with a zx9B motor taken out to 950cc and intend on using the stock 9 CV's, however its a roady so I thought CV's would e better. I do have flatslides on a zxr400 SP and they are sweet. cheers

regards TK400