Reed Valve Conversion, non typical

[pak39]

As many know, and have experienced, most of the time when one converts their engine to reed valve intake through the stock jug intake there is usually a loss of top end power. I converted my engine to operate on a reed valve intake at the beginning of the year and I also noticed this loss of power at the top end, but the low-mid range power picked up quite a bit.

The first two pictures show my first conversion.

The problem I had was my engine seemed to be starving on intake charge at higher RPM's which limited power and after thinking about it for some time I concluded that it had to be because of the small intake.

If you ever look at a proper reed valve engine, that's not case inducted, the intake is at the very bottom of the jug so I tried to copy this concept by cutting a big hole in my jug. Well I cut up an old jug to see if it would first.

The last three pictures are an old jug.
I also drilled and tapped holes into the jug to see if that would work too.

 

[pak39]

Keep in mind those are not through holes.

This is what I came up with, don't mind the ****ty welds and excess epoxy. I still messed up with this one because I didn't measure twice I took off too much material at the top of the big square port so I am not able to run a bottom piston ring, Oh well. I'm gonna try this conversion again, I've already got a new jug on the way.

Conclusion; I went from a top speed of about 31-32 mph to 37-38 mph, which is a big difference. However it did take away some low end power. I think once I build my expansion chamber it will give it a real kick.

 

[frank66]

the reason they dont go fast is that the piston window is allways completed very very wrong.also the rse reed is tiny.

if you lower the inlet floor a 1/4" it will come together much better. if not the window will need to be bisecting the rings.

get the larger 40mm rse reed kit with 4 petals maybe cause jbweld/epoxy hates 2stroke gas and vibration.

let me know when u get the next cylinder ready. cheers!

 

[pak39]

I've had pretty good luck with the high temp epoxy so far.
I got a jug with the 40mm bolt spacing coming and I'm gonna try it without cutting it up like this one first. I'm hoping the larger port will permit less turbulence for the intake charge, which I believe is what causes it to starve at high rpm's.
I've got a 4 petal reed cage at the moment with fiberglass reeds and they run great.

http://www.ebay.com/itm/FIBER-reed-...ngine-Quads-/231430403370?hash=item35e253b52a

Like that one, and as you can see is inexpensive.