bigjake

does anybody know if its possible to put gixxer 1100 flattops on my 88 13b?, id need a manifold made, i know that, but is it doable, any engine management suggestions??

Latin270

88 stock port 13b ??? NO wont run right!

mazdaspeed7

Ive been very interested in trying something similar. I think it would work pretty well with CV carbs. There are so many more tuning circuits than automobile carbs that I dont think it will need to be modified, just jetted. Im not familiar with those particular carbs, but you will want to be sure more than just one needle is available for them. The gixxer needle may not suit a rotary.



I know Keihin FCR's(flatsides) have a number of needles available, as well as a full range of main, slow, and air jets. And they are slide throttles to boot, so there is serious power potential.

bigjake

can anyone on no pistons help me fab a manifold for it?

mazdaspeed7

I could make you one. PM me if you are interested.

Tom93R1

I know the Sprint/metro/swift guys run bike carbs as an upgrade, but I would have to think there isnt as much potential gain with those carbs on a rotary. They come from a vehicle that probably makes about the same power than a stock 13b car, what size are the carbs? And how do you plan on plumbing them? 1 per rotor like a Weber? Or would you stage them into a primary and secondary setup and run 3 or 4?

mazdaspeed7

The 38mm keihin CVK's on my zx7r will do fine at 150 whp on a stroker motor. Jetting is available for nearly twice the amount of fuel flow needed to support that. The Gixxer carbs he is referring to should be a bit bigger, maybe 42mm.

bigjake

probably 2 per rotor, but im only a 1st year in my second semester of auto tech, so id need help with the engine management part, and probably alot of other stuff, like how/where to get it street ported

mazdaspeed7

If you have never tuned a set of CV carbs on a bike you have no business trying to adapt them to another engine. Not trying to be a dick, just save you a ton of heartache. The carbs are a pain in the *** to adjust, I probably have 30 hours into the jetting alone on my bike, and I had instructions on tuning these particular carbs with this particular jet kit, as well as prior tuning experience. It may not be so bad on a car where you can possibly get to everything you need on the carbs without major disassembly of the car(my bike required the front fairing, gas tank, air box, and throttle tube be disassembled to get to the carbs).



Its not like tuning EFI where you have real time feedback. With carbs, you make a change, run it, make another change, run it again, repeat, repeat. To tune full throttle, you adjust the float level for low rpm, needle position for mid rpm, needle taper for mid rpm and the transition between low to mid and mid to high, and main fuel jets for high rpm, and a main air jet for high rpm as well. For idle and cruise, you have a pilot jet, an air jet, and a mixture screw. The pilot jet feeds a series of holes that get uncovered as the throttle opens, while the one thats always has a needle valve on it for adjusting the idle mixture. Adjusting either the pilot jet or the idle mixture screw results in a change to the other. In addition to all that, the emulsion tube affects every bit of that. Not all carbs will have all of those adjustable, my kawasaki carbs had fixed main and low speed air jets.



Bike carbs are very complicated, and many of the changes overlap, and sometimes negatively affect other areas of the tuning. All this adjustability will likely result in the carbs not having to be modified specifically for a rotary, such as holley carbs. But with that adjustability comes extra complexity, and exponentially increases the learning curve for tuning them. In addition, carbs cannot compensate for changes in weather, so for all practical purposes, they only run to the potential of their tune when the weather exactly matches that of when they were tuned. I can tell a difference in how the engine runs with a 10 degree change in ambient temp.

bigjake

i bought the carbs from a friend for 30$ and thought it would be cool if i ever had the time to do it, where can i get bigger jets from?? is there a double weber set up that would be easeir??