Reed valves and inlet duration.

[mech_engineer]

I hope this will help you.

 

[Theon]

This is very interesting,
However still curious as to what can be gained whilst not going to case induction.
Case induction is the obvious route to Max power, and plan at some stage to try this,
However also curious as to what gains can be made without compromising piston or going case inducted? So will try what I have for now.
Thank you for your sharing.

 

[mech_engineer]

Ok i will send the pictures send me you email u got the area needed there for what u want

 

[mew905]

The problem with this engine: the intake port is to small..

You've come to the same conclusion I did it's just too restrictive. Transfers are also terribly angled, the exhaust side of them actually points at the exhaust, short circuiting like crazy. We need to find a way to correct this. Every time I see a high performance 50cc motor, they use a 21-25mm carb, definitely not 15mm like we get, they usually have 3-5 transfers, we can do 3 easily. Arrow's high end reeds use an 18mm mikuni, and their race engine uses case-inducted reeds with a 21m carb. I figure 19mm is the max we can use effectively using the 40mm bolt spacing (using 6mm bolts, with a 10mm head, gives us 30mm between the two bolts. using a 1" intake pipe, you can get a 3/4" (19mm) I.D. intake, not restricting flow at all, and leaving 2.3mm between the bolt head and the pipe/weld so you can actually turn it. This will also match your exhaust size. I actually wonder if making the intake exceed the exhaust size (basically case reeding is the only option doing this), if it will impact performance in a bad way. But for sure, the 2 major things to deal with: short circuiting and intake/carb size.

 

[Theon]

With the Dremmel, I take as much as I can from the top of the transfer tract on the exhaust side, I don't know that I have eliminated short circuiting, but someone suggested using a tube and blowing smoke through the transfer port, to get an indication of flow. When I do this I get a nice swirl in the chamber, and looks to be working OK.