| View previous topic :: View next topic |
| Author |
Message |
B Thomas
Joined: 20 May 2007
Posts: 107
Location: United States, Circle Pines,
|
|
| Back to top |
|
 |
Greg Wright
Joined: 25 Oct 2001
Posts: 2494
Location: United States, Indiana, Clermont
|
 Posted: Fri Apr 20, 2012 7:08 am Post subject: |
 |
|
The hot rod spirit lives!! 
_________________
Greg Wright
Rapid Racing Inc.
NKN Columnist & Host "Karting News Live"
I AM INDY!!
"When in doubt, gas it. It won't help but it ends the suspense." |
|
| Back to top |
|
|
al nunley
Joined: 13 Nov 2006
Posts: 3027
|
| Posted: Fri Apr 20, 2012 11:21 am Post subject: |
|
|
Why the piston porting on either side of the wrist pin?
_________________
If the data does not support the theory, get a new theory. (Al Nunley)
All else being equal; Compression is the Holy Grail.
45 years, in and around karting |
|
| Back to top |
|
|
Greg Wright
Joined: 25 Oct 2001
Posts: 2494
Location: United States, Indiana, Clermont
|
| Posted: Fri Apr 20, 2012 11:30 am Post subject: |
|
|
C'mon Al, This isn't that hard, the ports in the piston will feed the "trench ports" in the cylinder wall.
This was common in the early days of rotary valve engines before the TT configuration was the standard.
It seems to me that there used to be a similar mod on some old open Macs back in the day. Now that I think about it I think it was called trench porting.
_________________
Greg Wright
Rapid Racing Inc.
NKN Columnist & Host "Karting News Live"
I AM INDY!!
"When in doubt, gas it. It won't help but it ends the suspense." |
|
| Back to top |
|
|
Steve O'Hara
Joined: 02 Jan 2002
Posts: 1062
Location: United States, California,
|
| Posted: Sat Apr 21, 2012 12:03 am Post subject: |
|
|
Greg,
Al's question has merit as it seems the openings in the piston are in the wrong place. I say "seems" because the port layout shown in the cylinder in the pictures resembles common porting done to the early Komet and Parilla motors and on those motors the openings in the piston would both be on the same side of the piston rather than straddling the wrist pin.
The Power Products port arrangement is similar to the McCulloch motors where the orientation of the wrist pin is on a line with the exhaust and boost ports rather than the European and Yamaha layout that has the wrist pin on a line going from transfer to transfer so the openings have to straddle the wrist pin just like the openings in the later model Mc 101 pistons
I am a bit surprised at the size of the holes in the piston relative to the width of the boost ports but that shouldn't do any harm as long as the piston isn't weakened too much.
Should work just fine.
Steve O'Hara |
|
| Back to top |
|
|
B Thomas
Joined: 20 May 2007
Posts: 107
Location: United States, Circle Pines,
|
|
| Back to top |
|
|
al nunley
Joined: 13 Nov 2006
Posts: 3027
|
| Posted: Sat Apr 21, 2012 8:16 am Post subject: |
|
|
| Greg Wright wrote: | C'mon Al, This isn't that hard, the ports in the piston will feed the "trench ports" in the cylinder wall.
This was common in the early days of rotary valve engines before the TT configuration was the standard.
It seems to me that there used to be a similar mod on some old open Macs back in the day. Now that I think about it I think it was called trench porting. |
That makes sense. It is a Power Products barrel. The piston must be turned 90 degrees from what I was expecting. Like the old Mc. And also, the wrist pin doesn’t go as high as the bottom of the exhaust port.
Now I see it.
_________________
If the data does not support the theory, get a new theory. (Al Nunley)
All else being equal; Compression is the Holy Grail.
45 years, in and around karting |
|
| Back to top |
|
|
John Crider
Joined: 12 Aug 2009
Posts: 98
|
| Posted: Thu Sep 13, 2012 7:32 pm Post subject: Piston |
|
|
The Macs had 2 different pistons.One had a cupped bearing on the exhaust side and the other was skirted. The exhaust side wrist pin bearing has to be covered. I don't know about the PP or Benders but it looks very similar to a Mac's design. Good luck and Happy Karting. 
_________________
Legacy K.A.R.T. Racing Wichita,KS |
|
| Back to top |
|
|
B Thomas
Joined: 20 May 2007
Posts: 107
Location: United States, Circle Pines,
|
|
| Back to top |
|
|
B Thomas
Joined: 20 May 2007
Posts: 107
Location: United States, Circle Pines,
|
|
| Back to top |
|
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Login to check your private messages
Login
