polishing ports

[garynonnah]

Hi guys....just stripped new sil 200 engine to change bearings/seal /crank all going well as not done this before.
but question is....is it worth polishing out ports in the barrel, and any other suggestions ....
cheers all.

[Dimitrios_231]

SIL casting is very rough and hard.
You can match the ports to the the manifolds and smooth them to aid the flow.
You don't need to polish the inlet,polish only the exhaust port.





I also had an imperfection at the exhaust port.A small bit at the edge was broken.I had to raise the port to smooth the flow.

[garynonnah]

cheers fella....appy days

[Dimitrios_231]

I found some pics from another SIL that I've done.

[Dimitrios_231]

It won't harm if you also smooth (not enlarge) the transfer feeds at the base.

[garynonnah]

thats cool....will let you know how i get on.

[Dimitrios_231]

Just to clarify,
cleaning and matching the ports only,is the minimum work that can be done without affecting port timing etc.
It doesn't improve by any means the power of an engine but it helps for a better running.