Exhaust Ports

[Max]

It seems that the rule of thumb around here when opening up a muffler, you
open the muffler to aprox. 80% of the exhaust port dimension.

My question is do you use the inner dimension closest to the cylinder wall or the outer dimension towards the head face that mates up to the muffler.

This particular exhaust port flares open to a larger diameter at the muffler side of the port.

Which is the correct baseline to size the muffler opening?

Thanks in advance for any replies.

 

[scottr]

Port

Max , I remember this question from a previous thread and the answer was to use the port size at the cylinder wall .

 

[tony marks]

hey scott. this porting thing is good ,i guess. but the mods ive had done really didnt involve porting as much as what ever dave an dan do inside the saw.
now they probably know they did port it but its not visable to thios sawers eyes.
i know what im sayin doesnt answer your question but thot id throw this in.
something these guys do involves a lot more than just exhaust porting..
not tellin u what to do,but they do alot more ,and can accomplish a lot more than just porting. buit u will learn a lot from it. im thinking if u once let one of the good modifyers on this site, ever get hold of u saw . you never going to be satisfied with less.iknow i wont.jmo have fun.bud . dont mean to get into u buisiness

 

[scottr]

muffler mod

Tony , max is asking about the exhaust port to do a muffler mod . He's not modifying the exhaust port .

 

[fishhuntcutwood]

This very same question just came up on another saw forum, and it was the measurment on the inside, at the cylinder wall that you go by.

Jeff

 

[Max]

Thanks scottr and fishhuntcutwood (check my profile interests Jeff we have some stuff in common "

Thanks again for the info....into the garage I go !!!

 

[tony marks]

yep scott u rite. i guess im just trying to get to what i think he will get to eventually. but really half the fun is getting there. plus he will learn a lot on the way.