ZRX1200 Carb Conversion

[IanDMacDonald]

TADracer I noticed you left your ACV tubing in-place. Can I delete the tubing, and cap the ACV ports?

[Bonz]

I have Keihin original mains 128, 130, 145, 150, and larger. That brackets the sizes you're looking for, but if those would help you, me know.

I've adapted Keihin CVK40s from the ZX11/ZZR1200 to the ZRX and they use the same jet styles as the stock ZRX 36mm Keihin carbs. Bought lots of jets over the course of the trial and error. Finally spent money on an air fuel ratio gauge, it would have saved me more money in jets than I bought the gauge for lol.

Rocky Mountain ATV sells the main jets individually for $7.99 a piece. Look under the carbureted Kawasaki KLR 650 and it's the same jets. The 393 series. I looked and they're the same back to at least the 2000 model year KLR 650.

N424-25B is the pilot jet, same ones for KLR 650 will function there as well. Rocky Mountain ATV has those in 35, 38, 40 and larger. Shouldn't need bigger than a 35. $7.99 piece as well.

If the ACV's are in place, no harm no foul. If want to cap them, no harm no foul there either. Might get a bit more popping on decel.

You will like the needle valve seats, they are pressed into the ZRX carbs don't have to worry about those o-rings.

[IanDMacDonald]

I have Keihin original mains 128, 130, 145, 150, and larger. That brackets the sizes you're looking for, but if those would help you, me know.

I've adapted Keihin CVK40s from the ZX11/ZZR1200 to the ZRX and they use the same jet styles as the stock ZRX 36mm Keihin carbs. Bought lots of jets over the course of the trial and error. Finally spent money on an air fuel ratio gauge, it would have saved me more money in jets than I bought the gauge for lol.

Rocky Mountain ATV sells the main jets individually for $7.99 a piece. Look under the carbureted Kawasaki KLR 650 and it's the same jets. The 393 series. I looked and they're the same back to at least the 2000 model year KLR 650.

N424-25B is the pilot jet, same ones for KLR 650 will function there as well. Rocky Mountain ATV has those in 35, 38, 40 and larger. Shouldn't need bigger than a 35. $7.99 piece as well.

If the ACV's are in place, no harm no foul. If want to cap them, no harm no foul there either. Might get a bit more popping on decel.

You will like the needle valve seats, they are pressed into the ZRX carbs don't have to worry about those o-rings.

I appreciate that very much. I ultrasonically cleaned the carbs. I just spent $150 at MikesXS for pilots and mains (38/40/42/45 pilots, 135/138/140 mains). I DO have two A/F gauges with an O2 sensor, but I'm using the original exhaust on the XS, and would feel bad cutting a hole into it for the bung. I ordered an o-ring kit from Kwick, along with the block-off plate for the K-TRIC. I did forget to buy o-rings for the ACVs. I'll circle back to that, and emailed Pete from Kwick, to see if he could add it to my order.

[Bonz]

You've got a great source for parts for the ZRX from KWICK. That's his forum name on the zrxoa.org. His company name is ELS, for "Expensive Lightweight Stuff" as he designs and sells lightweight replacement parts for stock parts, as well OEM parts like valve cover gaskets, I've ordered replacement Speedo cables from him, that type of thing. He's not the cheapest but he's a good guy to support with buying some parts. You probably seen that if you've been on his site.

My instinct is you are in good shape with the main sizes. Be surprised if you go larger than 38 on the pilot. 35 is stock with those carbs when on the ZRX.

Dialing the ZRX in with the AFR gauge in the last couple weeks, the difference between a 38 pilot and a 40 pilot in the CVK40 carbs is huge when it comes to the fuel it provides. Pilots provide a lot more fuel than folks think.

Find the main that gives the best feel at high rpm as I totally understand not wanting to put a bung in those exhaust pipes. Then dial in the needles for WOT and roll on acceleration from low RPM and in the mid-range and also the feel at cruise. Then start looking where you are on pilot screw turns. That will determine where to ultimately end up with the pilot size.

As soon as the bike will run and hold a steady idle sync the carbs. That's going to make the whole process easier. A sync that is off will make you chase other stuff 'til you are blue in the face.

Keep posting, I threatened to do this when I had my SG, but never did. Looking forward to following!