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Anybody old enough to know what this is? LOL
Kawasaki used a keyhole shaped carb back in the 70s and there have been several variations over the years. Lots of aftermarketeers have offered offset bore carburetors. Today we have this shape patented and the predictive technique used to design it. PSI actually was infringing on our patents a year after they saw an SC at the hillclimb in Jackson. So as gentlemen we offered Bruce Kahlhammer a licensing arrangement to continue selling the V shaped venturi they had started using, (not the early D shaped big air they have patents for) however after some rude discourse we ultimately had to serve them with a cease and desist order. Turns out the design they had didn't work all that well and they weren't selling enough to really matter. You'll note they had large scallops cut into the venturi to diminish laminar flow and frankly were going in the wrong direction. I'm not sure they are even still in business, which is too bad, they had some pretty cool stuff at one time.
thats not bad, all things considered, and with the new technology theyre using. i have a idea for a twin cylinder engine totalling 500cc. if it ever makes it to fruition i estimate about 4.5 hp per CI or .28 per cc, using gas and a standard keihin or mukini style carb and no fancy electronics of any kind. seems like the size of your wallet is always the determing factor :highly_amused:
Snowmobile engines do not usually have their power over as wide of an RPM range as engines with transmissions. It is a lot easier to make huge peak power numbers if you do not need it over a wide RPM range. The CVT can hold the engine at it's peak power.
Most two stroke engines can be a little rich in the RPM range before the power peak without appreciably affecting the power in this range. A two stroke that is rich after the power peak will not rev and may have a rich miss-fire. The majority of the highly modified two-strokes I have worked with will be too lean in the RPM range before the power peak if we install a main jet that supplies the correct amount of fuel in the RPM region past the power peak. An engine that has the mixture correct in the RPM range past the power peak will have good over-rev and will run clean in this RPM range.
Knowing these facts forces us to make a choice of how we tune our carburetors, gear our bikes and then ride our bikes. Once we make these tuning and gearing choices we must ride our bikes in a manner for which it was tuned.
Tuning state #1.
If we ride our bikes on a closed course track where we never reach a speed in top gear where the engine will need to rev past the power peak, we can install a main jet that will produce the best power and acceleration up to an a few hundred RPM past the power peak. If we take this engine package and gearing and try to run it WOT in top gear where it will try to rev a 1000 RPM or so past the power peak, it will probably have a rich miss-fire in that highly over-reved RPM range.
Tuning State #2
If we decide to take our closed course bike and not change the gearing and just run it WOT in 6 gear we can usually lean the main jet and get a few more MPH and not hurt the engine. With this leaner main jet the engine will probably be too lean in the RPM range before the power peak and we may hurt a piston if we ride it with these carburetor setting on a closed course or pull a hill where the engine is pulled down to the RPM range below the power peak.
Tuning State #3 If we want to do most of our running at top speed and get our highest top speed, we can use our carburetor setting and maybe richen it up a jet or two over what we used in tuning state #1, providing we take enough teeth off of the axle sprocket or add teeth to the counter shaft sprocket so that when we run it WOT in 6th gear, the engine peaks or does not have enough power to pull no more than a hundred RPM or so past the power peak.
