Exaust(ive) Opinions please

[mpfine]

It looks to me that the exauset restriction is built into the head. Oh me of little real world experience. The exhaust port looks larger at the piston and at least a bit smaller at the out side of the head. The exhaust pipe opening is at least 40% larger than the port.

I scraped out about 1/8 teaspoon of oily sludgy material.

Whadda ya'll think of this? And, is there and benefit to opening up the port on the out side of the head?










I dont see much material back there to support opening the port.

[Rune 75]

Nov 16, 2017 12:51:25 GMT -5 mpfine said:

It looks to me that the exauset restriction is built into the head. Oh me of little real world experience. The exhaust port looks larger at the piston and at least a bit smaller at the out side of the head. The exhaust pipe opening is at least 40% larger than the port.

I scraped out about 1/8 teaspoon of oily sludgy material.

Whadda ya'll think of this? And, is there and benefit to opening up the port on the out side of the head?










I dont see much material back there to support opening the port.

Don't think the port is any bigger at the piston, you're being tricked by the shape of the port (optical illusion), im thinking the port is higher where you fit the exhaust. I've had some cylinders look like that but never thought of it as a restriction. Pretty sure it won't do anything good porting it.

[spaz12]

90GTVert opened that exhaust port before and noticed little to no gains.

[pinkscoot]

Thats how they come. If you get a BBK the exhaust port is larger to handle more air moving through.

[90GTVert]

Stock 49cc; I'd expect you don't see any real change. If you open up the rest of the exhaust and target a duration and larger chord width and add a tuned pipe, then it may make a difference.

[mpfine]

Thank you for all your responses.