Kioritz

malone · Post by **malone** » Tue Dec 30, 2008 1:53 am

What exactly do reed valves do, and why do some engines have them and some dont? are there any reed upgrades for old Kioritz engines,

400brian · Post by **400brian** » Tue Dec 30, 2008 3:00 am

Basic 2 stroke induction design: Piston port, and reed valve induction.

Piston port engines have the intake manifold attached to the side of the cylinders.

Reed Valve engines have the intake mounted to the crankcase. The reed is simply a one-way valve, Allowing the fuel mix into the case, but preventing the mixture to be pushed back out .

malone · Post by **malone** » Tue Dec 30, 2008 3:02 am

is one better than the other??

Post by **Matt** » Tue Dec 30, 2008 10:09 am

As I understand it, they originally used reed valve engines to get more performance for less money. However, well-built and tuned piston port motor can perform better then a reed valve motor, but it cost more to build. For example:
The 100 series were mostly piston port.
The JDX series were mostly reed valve, but had better performance then the 100 series motors.
The 295/S, 340/S, and Liquidator were all piston port, but were better performing then both the 100 or JDX.

malone · Post by **malone** » Wed Dec 31, 2008 4:06 pm

Ok, Thanks.

Dave

big danno 1970 · Post by **big danno 1970** » Thu Jan 01, 2009 2:11 am

Reed valve engines typically have better bottom and midrange power and also better fuel mileage.This is because the fuel/air mixture is not allowed to spit back through the carb when the engine is not in its ideal "power band".This also helps mileage because as the fuel gets spit back and then sucked back into the piston port engine it pulls more fuel on the way so it is actually a really rich mixture (dubble carburated), the reed valve engine can be jetted leaner because of no spit back.
A reed valve engine with an exhaust power valve is even better because the power valve lowers the exhaust port via a gate of some kind at lower rpms to prevent unburnt or raw fuel from escapeing into the pipe,then as the rpms increase the power valve opens to allow the engine to run on the pipe in its "ideal power band" thus you get good bottom, midrange and top end power as well as good fuel mileage.
Hope I didnt confuse you.

S_Kyle · Post by **S_Kyle** » Thu Jan 01, 2009 3:03 am

Do you know when the power valve started showing up on sleds? models?

JDT · Post by **JDT** » Thu Jan 01, 2009 11:54 am

Good explaination Danno.

big danno 1970 · Post by **big danno 1970** » Thu Jan 01, 2009 1:09 pm

I think mercury started useing them(reed valves) in 1970 on their 250 model, interesting that they also had electric start reverse or direct reverse (the engine ran backwards) something that ski poo I mean Ski doo tried to claim to be the first.
Not sure on what model was first for reeds in the JD line.

big danno 1970 · Post by **big danno 1970** » Thu Jan 01, 2009 1:12 pm

Thanks JDT, I had to do some serious thinking on that one.