morbius18
ArboristSite Operative
I picked up a really clean ms250 with questionable bearings. I figured I'd widen the ports. I decided to see what the numbers were.
Bore: 42.5mm 65% bore = 27.6mm
Intake: 80° stock port width: 19.9mm
Exhaust: 98° stock port width : 21.5mm
Transfers: 129°
Squish: .039"
I double checked the initial setting TDC after getting 129°
I can go quite a bit wider on the exhaust port, but the intake port has both rings visable and close to the sides of the port. Is it ok to widen the lower part of the port and leave the top narrower? I can also remove the bottom ring as well.
Sketch of port shape on left with dotted sides. Will be similar to the right sketch.
Bore: 42.5mm 65% bore = 27.6mm
Intake: 80° stock port width: 19.9mm
Exhaust: 98° stock port width : 21.5mm
Transfers: 129°
Squish: .039"
I double checked the initial setting TDC after getting 129°
I can go quite a bit wider on the exhaust port, but the intake port has both rings visable and close to the sides of the port. Is it ok to widen the lower part of the port and leave the top narrower? I can also remove the bottom ring as well.
Sketch of port shape on left with dotted sides. Will be similar to the right sketch.