Mastermind
Work Saw Specialist
Here's the intake after roughing it in. It had 148° of duration stock, I lowered the port enough to get 158°. I also widened it to around 26mm which is about 65% of cylinder diameter. Notice the nearly rectangular shape of the port, this gives the port more mean area, which means more flow. The rings don't ride across the intake port so a flatter floor and roof is possible.
The exhaust port has a steel insert in it from the factory, after removing it I widened the port to 68% and squared up the corners. The lip inside the port has to be retained or the port timing is altered. This port opens at 101° ATDC and has 158° of duration.
Sorry about the blurry pic. I'm trying something I've never tried or seen before here. Even though these are open transfers I've widened them towards the intake port in hopes of more power. I figured out how much the ports open and then widened only the portion of the port that opens. I may have screwed the pooch here, but we'll see.
The intake partition I port matched to the jug and blended back to make the transition from round to square happen less quickly. Now I will spend some time smoothing these ports and chamfering the edges to keep the rings from snagging.
I hope this answers some of your questions.
The exhaust port has a steel insert in it from the factory, after removing it I widened the port to 68% and squared up the corners. The lip inside the port has to be retained or the port timing is altered. This port opens at 101° ATDC and has 158° of duration.
Sorry about the blurry pic. I'm trying something I've never tried or seen before here. Even though these are open transfers I've widened them towards the intake port in hopes of more power. I figured out how much the ports open and then widened only the portion of the port that opens. I may have screwed the pooch here, but we'll see.
The intake partition I port matched to the jug and blended back to make the transition from round to square happen less quickly. Now I will spend some time smoothing these ports and chamfering the edges to keep the rings from snagging.
I hope this answers some of your questions.
