Size on inlet and outlet ducts?

[Adaware]

Two valves per cylinder. How big should the inlet and outlet port be?
Cylinder volume if about 40-50ccm

Don't need racing specs here. Just want it to be reasonable :-)

[stevehuckss396]

Originally Posted by Adaware Two valves per cylinder. How big should the inlet and outlet port be? Cylinder volume if about 40-50ccm Don't need racing specs here. Just want it to be reasonable :-)

I try to keep them 1/3 the size of the bore. Don't know why, just know it works.

[dynosor]

Originally Posted by stevehuckss396 I try to keep them 1/3 the size of the bore. Don't know why, just know it works.

What Steve said sounds good. If you get greedy with large ports the gas flow velocity suffers. This degrades fuel atomization and low speed cylinder filling, leading to very hard starting and poor low speed performance. Err on the small side.

[Adaware]

Hmm, 12-14mm is the best i can do in this engine. Like i said in the other thread it's very limited space on this engine. Maybe i will post a thread about it.

It's not a project in the making but more like a cad project while learning to draw in Solidworks. The thing is that i want the engine to actually be buildable so i need sizes that's possible to work with

Thanx once again for help