MS440 Transfer Porting

[Dibbs]

I've been toying with the thought of changing the inlet and exhaust ports on my MS440 for woods use.
Does anyone have any idea how much to raise lower each of the ports to best suit my needs.
It's a standard Stihl Cylinder/Piston of the newer con rod type.
I'm not interested in modding the transfer ports but may give them a polish up if I think it's required.

I'm mostly interested in the exhaust port and the rpm/power/torque from removing material from top or bottom.

 

[Danger Dan]

I've been toying with the thought of changing the inlet and exhaust ports on my MS440 for woods use.
Does anyone have any idea how much to raise lower each of the ports to best suit my needs.
It's a standard Stihl Cylinder/Piston of the newer con rod type.
I'm not interested in modding the transfer ports but may give them a polish up if I think it's required.

I'm mostly interested in the exhaust port and the rpm/power/torque from removing material from top or bottom.

Hey Dibbs, I'm not sure what your "needs" are, but have you set the squish or opened up the muffler? If you raise the exhaust too much you will lose torque. :smoking:

 

[timberwolf]

This server too busy crap is pi55en me off!

I would not go wild on raising the exhaust, It can stand a little, but I'm only talking 0.5 mm above stock, setting the squish down to .020 as DD mentioned is a good start then if the exhaust is brough up just a little over stock it will be decent. It would be nice to raise or extend back the transfers a little to regain the lost time area dropping the jug caused, but not esential if you don't want to go there. The slight jug drop to get the squish down will also extend the intake duration a couple deg. For a basic port job on a 440 I would focus more on widening out and getting good shape on the ports than extending duration. The lower part of the transfer duct can be cleaned up faily easily too.

Unless you go to a full port job and rework the transfers and other things doing much to the intake duration could cause more harm than good.

 

[Dibbs]

Squish set to 0.020 Inch. (or 0.5mm for the Metric World)
Transfer Ports cleaned up and raised to suit new gasket.
Exhaust Port raised to suit new gasket, widened a little and polished.
Intake Port cleaned up and widened a little and left with semi smooth finish.
Piston polished to remove carbon build up.
Exhaust Baffle hole, Gasket and Cooling Plate Widened to match Exhaust Port on Jug.

Thanks to Danger Dan and timberwolf for their help in this thread.
Thanks to Erick for his posts in the Thin gasket material Thread
Thanks to www.arboristsite.com and it's Members for the many Threads I've read before undertaking this Project.
And last, but by no means least, thanks to Dremel for their wonderfull little tools.

I havn't got a chance to run it yet in some logs but I have a feeling it has been a success, but, even if it has been a failure I've had fun giving it a try!

 

[Danger Dan]

By your description, I think it should run strong...let us know opcorn: