Education Needed

Danzig · Post by **Danzig** » Thu Jan 19, 2006 2:35 pm

What does it do?
How does it work?
Where is it located?

JDXsand00s · Post by **JDXsand00s** » Thu Jan 19, 2006 2:51 pm

the reed valve is a valve made out of reed which only lets air'gas mix in and not back out of the cylender improving efficiency. it is under the intake manifold which the cab bolts too. i'm pretty sure that since the reeds are so thin that gas is easily sucked in but it can't get back out as pressure goes against it. tittl probably has the sm with the diagram showing how piston ported egines work in operation.

JoeRainville · Post by **JoeRainville** » Thu Jan 19, 2006 3:00 pm

Hi Guys,

There are two types of reed valve two stroke motor: case reed and cylinder reed. I will describe case reeds here first.

Case reeds take the place of piston porting a motor. On a piston port motor, like most Kawi sled motors and early CCW's, fuel can only enter the crank case after the bottom of the piston skirt raises past the air/fuel/oil inlet port (carb or intake manifold mount) on the side of the jug. Air/Fuel/Oil mix then enters the bottom of the motor until the piston starts is trip back down the cylinder, closing the port.

The carbs mount on the crankcase of a case reed motor. As soon as the piston starts moving upward and creats enough vacuum to overpower (open) the reeds, air/fuel/oil enter the crank case. As the piston starts back down the bore, the reeds are forced closed, the positive pressure in the crankcase forces the air/fuel mix up into the transfer ports and the the combustion chamber for compression and ignition to take place. This also helps to purge out exhaust gas too, before the exhaust port is closed by the rising piston.

What case reeds also allow for are larger transfer ports since there is no hole in the center of the bore for air/fuel to enter below the piston. Case reeds also reduce 'spit-back' of fuel that all piston ports are noted for.

They work like a flap opening with vacuum and being closed shut by spring force and air pressure. They help control and stabilize flow velocity into the case by opening farther as air/fuel flow increase accross the reeds.

Cylinder reeds act as fuel control on a piston ported motor. It's not as effective as case reeds, but make dropping the motor lower into the chassis possible, for better packaging. They are supposidly better for high RPM flow stabilty of the 'pulsed' intake flow.

Odd to note that by using SS reeds on the production motors, (73 JDX-8 with it's KEC 440/21 motor was first) Deere chose to make all the race sleds piston ported for higher RPM performance. Also, all Deere/Kawi Fireburst motors were piston ported, probably to keep cost down. Now, most sled motors are either case or cylinder reeds for high performance. Most reeds are now either carbon fiber or composite materials, but not SS like CCW-Kioritz used.

I hope this answers your questions...
-Rainville

Danzig · Post by **Danzig** » Thu Jan 19, 2006 3:01 pm

Reason I am asking is that I reviewed the operator manual that I recieved today and one of the problems that i have on the X8 is like a popping out of the carb and the book does say one of the problems is a faulty reed valve. I dont think a crank seal is a problem, I sprayed the hell out of the motor with carb cleaner and dont see any RPM fluctuation.

Can the reed valve be cleaned or should this just be replaced?

Better yet, is there a trouble shooting schematic on this valve for proper operation?

JDFanPa · Post by **JDFanPa** » Thu Jan 19, 2006 3:10 pm

Danzig if you pull yours apart you can see how they work on the x8 motor. Its possible over time they could be distorted and not seal right another thing is if water gets in the carb during storage etc on these it will run right down into the reed case if you get rust down there surely that can prevent proper sealing aswell. I have seen these quite rusty on a few motors Ive pulled apart that got water logged.

Danzig · Post by **Danzig** » Thu Jan 19, 2006 3:26 pm

JdFanPa-

Were you able to salvage the valve after seeing the rust?

JDXsand00s · Post by **JDXsand00s** » Thu Jan 19, 2006 8:27 pm

if there is rust on the reed valve you can clean them with some scothbrite, works pretty good and gets them nice and shiny.

Danzig · Post by **Danzig** » Thu Jan 19, 2006 8:45 pm

I used the Carb cleaner based off my automotive exp. when checking for vacuum leaks, never new that is would swell these seals, maybe I fixed a bad seal

JDDDeere · Post by **JDDDeere** » Fri Jan 20, 2006 12:10 am

My 2 cents... (or so I've been admonished by my snowmobile/small engine repair buddies) is that carb cleaner can be very detrimental to certain plastics and should be used sparingly and for carbuators only. I recall the "seal check" invovles starting fluid (ether) and not carb cleaner.

Like I said, just my 2 cents (maybe 1 cent), and perhpas you did cause it to swell, but my experience is that it tends to dry out rubber parts.

Have a good night!!!!!!!!!

Waiting for snow (maiden voyage coming up for a 1978/1980 Spit!!!)

Dan

Danzig · Post by **Danzig** » Fri Jan 20, 2006 1:11 am

I may have also used Liquid Wrench when I first got the sled. Oh well.

JDFanPa · Post by **JDFanPa** » Fri Jan 20, 2006 3:52 am

like stated Danzig scotchbrite works pretty well

Danzig · Post by **Danzig** » Fri Jan 20, 2006 3:54 am

I will have to take a look and see what i may be dealing with.