James Sawyer
ArboristSite Operative
I've been working on this old saw of my dad's, and I can save the OEM cylinder, but it needs a piston. I don't have a mandrel so I'm looking at a base gasket delete. I'm trying to decide on what piston? The OEM timing numbers aren't bad with gasket. The exhaust is at 100 and blow down is 19... the intake with gasket delete not quite what I'd like.
So... I did some piston comparison between the OEM, Meteor and Hyway Popup. Bottom line there are some differences. I know I could have bought an OEM piston for what I paid for these AM pistons, but I wanted to learn something about these popups.
Hyway piston is heavy...105.5 grams, you'll have to decide for yourself if you think they are close to the OEM measurement as far as piston skirt lengths etc. My thoughts the Hyway could help a little with the intake time if I did a base gasket delete. If I went with the Hyway a course I would want to check the timing number before deciding. The longer Hyway skirt would give me about degree on my intake numbers after thinking about it. The Meteor is direct replacement with the OEM. Here are my measurements (PT = piston top). I included a few photos as to show how I did my measurements, they were done on a mapped machinist granite so their accurate!
I'm assuming I'd increase the exhaust and intake timing about 2.25 degrees with a base gasket delete. The squish is like .043 if I remember right.
OEM Meteor Hyway
Wt. 97.0grams 98.0 grams 105.5 grams
intake to PT 1.560" 1.556" 1.690"
Ex to PT 1.723" 1.722 " 1.728" (popup is 022" or the number would be 1.750)
PT to bottom pin 1.357" 1.361" 1.3775
The casting on both the Meteor and Hyway both need some work, hard to say which one is worse. I think the window on the Hyway are better thou. The skirt on the intake isn't flat on either AM. The Hyway had casting flaws on the intake.
I was always curious about these popup pistons but never used one and I really couldn't find much on them. This MS461 with its wrist pin height I think as a tendency to rock in the cylinder... with the extra wt. of the popup it would make it worse.
Has anyone had any experience with these popups and done a base gasket delete. Should I delete the base gasket with popup? I just thought I'd ask for some input.
So... I did some piston comparison between the OEM, Meteor and Hyway Popup. Bottom line there are some differences. I know I could have bought an OEM piston for what I paid for these AM pistons, but I wanted to learn something about these popups.
Hyway piston is heavy...105.5 grams, you'll have to decide for yourself if you think they are close to the OEM measurement as far as piston skirt lengths etc. My thoughts the Hyway could help a little with the intake time if I did a base gasket delete. If I went with the Hyway a course I would want to check the timing number before deciding. The longer Hyway skirt would give me about degree on my intake numbers after thinking about it. The Meteor is direct replacement with the OEM. Here are my measurements (PT = piston top). I included a few photos as to show how I did my measurements, they were done on a mapped machinist granite so their accurate!
I'm assuming I'd increase the exhaust and intake timing about 2.25 degrees with a base gasket delete. The squish is like .043 if I remember right.
OEM Meteor Hyway
Wt. 97.0grams 98.0 grams 105.5 grams
intake to PT 1.560" 1.556" 1.690"
Ex to PT 1.723" 1.722 " 1.728" (popup is 022" or the number would be 1.750)
PT to bottom pin 1.357" 1.361" 1.3775
The casting on both the Meteor and Hyway both need some work, hard to say which one is worse. I think the window on the Hyway are better thou. The skirt on the intake isn't flat on either AM. The Hyway had casting flaws on the intake.
I was always curious about these popup pistons but never used one and I really couldn't find much on them. This MS461 with its wrist pin height I think as a tendency to rock in the cylinder... with the extra wt. of the popup it would make it worse.
Has anyone had any experience with these popups and done a base gasket delete. Should I delete the base gasket with popup? I just thought I'd ask for some input.