S-25, 4.6

[digger]

Haven't seen this posted yet. If it has been, I'm sorry.
Did they use the same case from the 25 to come up with the 4.6?? As in putting a bigger piston and/or a longer stroke to come up with the other 3cc's.

May sound like a stupid question, but some of the aircraft engines are advertised .46 in a .40 case. Saito's 1.00, 1.00 in a .91 case.

If ya think about it, it would be cost effective for the manufacturer. They already have the tooling. If they could just put a bigger piston in it and come up with more power, all they would have to tool would be the sleeve and piston.

Just wondering whether some of us with the 25 could buy a few parts and convert ours to a 28?

 

[dougc]

I am sure that all of the .21s to the .28s use the same size case of a .21 now I am not sure if they made a new one. my s-25 is black unlike the other s-21 but is says 3.5cc when you do the math that is a .21 and my ofna .26 force (came with my buggy) say is is 3.5 also but ofna says it is a .26 .

 

[jon2]

We are talking minimal changes in displacement. Not sure they would take that as using a larger crank case. Now if we are talking a .12 to a 26 then yes.

 

[AC48]

All crank cases for .21-.28 are the same basic size, however, the K4.6 case is a new design from the S-25.

 

[digger]

Thought maybe I could buy a piston and sleeve and have a .28. Oh well. :shrug: May go ahead and do the mod on the 25.
Thanks guys

 

[markallen]

Thought maybe I could buy a piston and sleeve and have a .28. Oh well. :shrug: May go ahead and do the mod on the 25.
Thanks guys

Do the mod.It is more than worth it..

 

[AC48]

Yeah, I would try a mod first, then if you mess it up by a .28