Poor boy's answer to a couple of porting questions.

Ax-Man said:

These are some good threads you have going Al.

Couple questions

I noticed you didn't do anythng to the intake port, other than polish it. I always thought or read that and from little porting I have done that if you alter the exhaust the same should be done to the intake port to keep the same amount of air entering the cylinder to be the same as what is existing out the exhaust. In other words if you widen the exhaust you should widen the intake the same amount. Does it even matter one way or the other because the amount of air volume is determined by what amount the crankcase can take in and hold.

I like your explaination about the muffler and how it works, much easier than some of those books I have been reading on the subject.

Now I will raise another question that might contriversial.

Ever since I have found out about modding muffler the norm seems to be to gut the muffler totally. I question this practice myself . I understand the why's of doing this for better flow and more power. Mufflers in most of today's saws seem to construsted not only to reduce noise but conduct heat away from the port and cylinder and tranfer it to the outer portion of the muffler. Most of the newer Sthils have a heat shield behind the muffle which to me acts like the exhaust manifold on a car engine. This is just my opinion and oberservation is that by gutting the muffler it loses it ability to conduct heat and weakens the muffler's internal structure. When i mod a muffler I try to improve the flow by either opening the baffles more or cuting out just small pieces in the direction of the exhaust flow.

This may seem to be on the conservative side but I also feel that gutting a muffler you affect the timing of the scavaging side of the cycle a little. This is just my own opinion is all. I don't have the answers because when it comes to modding saws I am just a shade tree mechanic but I am always open to a good disscussion and to learn more.

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