Reed valve

I run the RSE Reed valve on my race bikes. I get a significant boost in low end torque, with no sacrifice in top end power for it.

I cannot recommend them enough if you are willing to do the modifications necessary for any Reed valve conversion:

The window in the piston is the most important part, if there was no window in the piston (or cut-away from the piston skirt) then you are not increasing your intake timing duration, witch is -among other things- what converting to a reed valve would allow you too do.

Alternatively, if a "boost port" is cut from the bottom of the cylinder bore (underneath the intake port) up through the intake port, and out the top, to the same height as the transfer ports, the piston modification is not required, but will still provide an improvement in overall flow, and performance.

The "boost port" also known as -in our case- the third transfer port (cut from the intake port, up, to the height of the transfer ports) increases the performance gained by creating another path for this extra intake charge (if you do indeed increase the intake timing) to get into the cylinder.


Reed Valve conversion without Piston Window or Boost Port = Meh

Reed Valve conversion with Piston Window and no Boost Port = Improved low end power, possible loss in top end (depending on window size/shape)

Reed valve conversion with Piston Window and Boost Port = Even more improved low end power, with more top end power too.


I run the RSE Reed Valve with this modification to the stock piston:




If you have any other question don't hesitate to PM me.

So here's a question, what does a boost bottle do in this mix? Would it increase perormance at all?

The $30.00 Reed on eBay works as well as the RSE For the China Doll but both of them require you cut the intake runner for a perfect fit or the reeds don't close perfectly.

Hi Ducati, I experimented with the rse reed valve, Walbro carb and ported piston of my own design. I did not quite have the excellent results that member Exo had.

I was looking for low end power and was not successful, however my bike would get on the pipe at about 22 mph and scream to 34 to 36 mph in flash. You could literally feel the seat of the pants thing in this midrange twisting the throttle on and off. I have a 10 1/2" header pipe on a sbp expando.

As I was experimenting more to find the low end I went a little
crazy on the walbro mixture screw and blew a hole in my piston the size of a nickel. LOL

As I did not find the need for my power band useful for cruzz'n I retired the experiment.

skitchfish said:

Hi Ducati, I experimented with the rse reed valve, Walbro carb and ported piston of my own design. I did not quite have the excellent results that member Exo had.

I was looking for low end power and was not successful, however my bike would get on the pipe at about 22 mph and scream to 34 to 36 mph in flash. You could literally feel the seat of the pants thing in this midrange twisting the throttle on and off. I have a 10 1/2" header pipe on a sbp expando.

As I was experimenting more to find the low end I went a little
crazy on the walbro mixture screw and blew a hole in my piston the size of a nickel. LOL

As I did not find the need for my power band useful for cruzz'n I retired the experiment.

Click to expand...

I did this exact thing in my tuning adventure, getting the power band I was looking for.

I have the piston with the hole in the top to prove it


I was also using a SBP type expansion chamber.

It is too small. Not too short (although it is shorter than I would like) but it's big problem is volume, and header tube diameter.

I found the power down low I was looking for with a pro circuit KX80 pipe, and Fred CR Machines "Fire Breather" exhaust header.

Without that pipe, or something equivalent, you will NEVER find the low end torque you are really looking for.

Ducati, I severely scratched the boost port cylinder from Dave Rust ( can't think of the name of his company ) and obviously the piston is a bad ash tray but the other stuff is available if you want

Exo , That's awesome you found the low end. I'm really not racing anyone back here in Michigan and just wanted to see what it is was all about. Got my low end back with old MM shorty intake for just riding around.

How did you do on the top? How fast do you think your going?

Proof:

skitchfish said:

How did you do on the top? How fast do you think your going?

Click to expand...

Radar gun said I did 50MPH at the end of the straightaway at Grange Motor Circuit.

That was with a 40 tooth rear sprocket, and running the track Counter-Clockwise, so the straightaway was going slightly uphill.

I could probably get more total top end speed, but the engines are built, and the bikes are gear for the track.

I really think you would enjoy the bottom end advantages of a sbp pipe. There is alot of guys adding another silencer in the end of the stinger and say it doesn't hurt it. It really isn't that loud until you grab all the throttle for a extended length of time. LOL

There is also that safety factor in being a little louder. LOL

It would be my opinion that using a reed kit without a performance pipe would result in disappointment.

Exo, Kudos to you, you can take off and keep rippin to 50 with a 40 tooth! I hope you own some trophy's bud. Congratulations on figuring it all out.

I know your the real deal because I remember seeing those radar gun speeds posted.

What is the racing number of your bike?

Here's pics of experiment gone bad

skitchfish said:

What is the racing number of your bike?

Click to expand...

Thanks a lot for the kind words man!

Bike #124, and Bike #154

Apollo Moto Racing, pushing through the limit.