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Why One Carb?

Install Video



Caretaker Photos


(Frequently Asked Questions)

How does it work?

Do I have to jet anything?

Is it cost effective?

What fuel economy can I expect?

What is the advantage of a single carb system?

Factory Setup vs. KJS Setup. Which is right for me?

Power and Torque?



One carb having two cylinders drawing air-fuel, creates the term "intake manifold pressure". To compare; duel carbs for example each pull 5,000 air/fuel molecules at 2 microns thick and the single carb pulls in this example 10,000 molecules at 1 micron thick, so when ignition happens, the molecules detonate from the out side to the inside, increasing the thrust or "bang" faster. -Back to Top-



Dual carbs systems due to the lack of constant intake manifold pressure, are very sensitive to exhaust systems. That and the fact that our bikes have low compression engines makes it much more difficult to get the jets set up correctly. With the KJS single manifold system NO JETTING will ever have to be done. Each carb is set up for your engine size (CC's) of bike. Nothing else has to be done. Your exhaust system should always have at least 10 to 20 % back pressure. The only pipes that aren't built with 20% back pressure, are straight through drag pipes. If you are using these pipes then and only then, the main jet may have to be changed. -Back to Top-



To get the same performance out of your bike that you would get with the single manifold system, you would need to make expensive upgrades to your bike - high compression pistons, cam shafts or jetting the dual carbs. The cost to get the same performance would simply be out of reach for most riders. All those accessories mentioned above are redundant now and not needed when you have the single manifold system. For hundreds less this system can be self installed saving you even more money and still delivering top performance. -Back to Top-



There is a huge difference in performance between Dual carbs and the single carb system. The biggest difference can be felt when shifting and twisting the throttle. With the duel carbs, passing and accelerating requires the engine to rev to it's max red line just to get there. With the single carb system you can simply leave it in 5th gear and roll the throttle on as required. V-Star/Virago dynograph in the web site shows a graphical comparison. What the duel carb system produces at 4200 RPM, the single carb system gets at 2200 RPM. You get the bang you need sooner. This is a High Performace and replacement system and was never intended to extend fuel mileage. -Back to Top-



The drawbacks to dual carbs are many. The primary drawback is that they never seem to stay in sync, thus creating an uneven charge to the cylinders. When the valve opens, it has to draw more than a singe carb, due to the lack of a more consistent manifold pressure, thus not drawing a better-atomized charge. This makes the duel carbs less effective. -Back to Top-


FACTORY SETUP vs. KJS SETUP. Which is right for you?:

If you are a city rider, or just use your bike for running errands, leave your bike the way it is don't change a thing. If on the other hand you like real time performance , and smooth acceleration when passing at highway speeds, even with two up, and you want a great sounding bike that will make others turn their heads, then consider the KJS single system. It all depends on your requirements as a rider. -Back to Top-



Now that the single carb system supplies a much better atomized charge, (constant intake manifold pressure) the torque is produced sooner with no lag. Your bike can now shift at a lower RPM and does not have to be RED Lined to get there. To put it simply, the torque and horsepower is produced 2 times faster - lighting the engine up. It's like the human heart, when it does not function properly it puts unnecessary strain on the starter and compromises the reliability and safety of your ride. With the single carb system you get the power and torque earlier in the powerband and you do not put any more strain on the engine. Not all of the fancy jet kits, exhaust systems, paint or chrome can do that. They may look good, but do they work? It's a science to truly understand it. A science that KJS has been studying for years. -Back to Top-