What to do with KS port bevels?

[Sauen]

Hi everyone,
This is my first time posting on here after having read many many threads, thanks for all the information.
In tearing down some saws which have Kolbenschmidt cylinders, I noticed that the bevels on the ports are almost non existant, whereas on Mahle and Stihl branded cylinders the bevels are much wider.
My question now is that when widening the intake and exhaust ports on these KS jugs, does the bevel have to be increased to as much is found in the Mahle jugs? On the 288 jug I opened the intake a little and then sanded all the bevels to become somewhat bigger, but on the 026 I did not do this and left it as from the factory.
Is the small bevel perhaps why most KS jugs are said to run well?

 

[John235]

I just noticed the same thing on a brand new 288xp ks. Barely any bevel at all. I am not sure why they are so different from the mahle as well

 

[Sauen]

Best to just leave it you think? They dont hang ring that I know of

 

[cus_deluxe]

If the roof is sufficiently arched you can get away with pretty minimal beveling like those ones you showed. Too much bevel, especially on sides, on wide exhaust can let that ring expand into ex port too much and hang it that way too

 

[Ketchup]

Small bevel is usually better but I have seen giant bevels on strong saws. Large bevels on port sides are a detriment. Large bevels on port roofs, especially exhaust, will help if the port is very wide or very flat.

It’s possible the larger bevels are cast into the jug, where smaller ones were finished after the plating.

 

[Basher]

I run .010 bevels on all my cut ports edges. I like the snappy exhaust sound they make.

 

[Sauen]

If the roof is sufficiently arched you can get away with pretty minimal beveling like those ones you showed. Too much bevel, especially on sides, on wide exhaust can let that ring expand into ex port too much and hang it that way too

Thanks for the reply, didn't think of the bevels on the sides not being necessary.

 

[Deets066]

A wide port with a big bevel can be bad, as Custer said you need sufficient arch. A stock port can perform just as good if it’s flat and tight bevel.

 

[old guy]

I changed oem cyls. on a 550 husky, both old & new had next to no bevel.