Porting cylinder without a crankcase

[computeruser]

What kind of results could be obtained porting a cylinder but not matching it/timing it to a particular crankcase? I’m assuming you aren’t going to be able to go 10/10 this way, but how good a port job could be done if someone had just a cylinder and a new piston to work from?

 

[cuinrearview]

@huskihl

 

[huskihl]

I don’t do anything to the case on most saws, so as long as I have a builder case to mock up on, it can be done. I won’t do it if I don’t have a case though.

 

[Bob Hedgecutter]

Kinda-grind and guess?

 

[TheAMMIXman]

One could certainly clean up the ports nice and not change the timing. I’ve had good results twice doing that with big bore kits on MS460 and an 046. They needed to be cleaned up anyway.

 

[AUSSIE1]

A base gasket can be a great template for doing the lower trans and port matching. So much work can be done cleaning up and widening. Port match the carb. Open up the exhaust and muffler.

If someone has ported the saw in question, measurements from the base will get you in to the ballpark with port timing. Considering many here run a wide range of durations, its not out of the question at all especially if the numbers are conservative.

 

[computeruser]

Well, I found a couple folks who are able to do this for me, which is great. Sounds like lots of folks are going to build/grind/test-fit over a mock-up crankcase anyway, rather than your specific one, where debris could get in. This way I can end up with a couple pre-ported P/C sets to have around for the future, where I can do the final exhaust blending to the muffler, mod the muffler, etc., myself, which is totally fine with me.

Now to get this work started and then find more saw carcasses to put these cylinders on!!