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BSA B50 / Porsche 911 top ends? #210140
07/02/08 4:33 pm
07/02/08 4:33 pm
Joined: Jun 2004
Posts: 1,115
Kansas
kboyd Offline OP
BritBike Forum member
kboyd  Offline OP
BritBike Forum member
Joined: Jun 2004
Posts: 1,115
Kansas
I saw this on the flattrack.com forum and thought some beezer guys might be interested...

http://s296.photobucket.com/albums/mm170/HPbyStan/BSA/

Click on pics for full size and a note of what you're looking at.

Porsche 911 stuff bolts right on a BSA B50. When I first started designing my own pistons I bought a S.A.E. book on piston design and spent two weeks drawing up what I thought I wanted. I sent it in to Arias Piston Co. and got a call back almost at once. I thought "OMG, I musta asked for something stupid" but the guy says, "Why didn't you just say you wanted a Porsche 911 piston"? Later I saw a 911 cylinder, head, and piston on eBay for cheap so I bought them. Turns out somebody copied somebody. The cylinder fits right on B50 crankcases and the B50 head fits right on that. What's REALLY weird is the stud pattern for the 911 Cam box is the same as the B50 rockerbox. People didn't believe me when I first said this so I took pictures of the combinations. Also on this album are pics of how far one needs to mill a BSA head apart before starting over to put things where BSA should have put them. At the end of the day it's sure easier to buy a Honda dtx bike but not as much fun when the competition is protesting you and you make more money for being legal as happened @ TMS (among other places) in the pictures Dale posted under the "Will Davis pic" thread.


Kyle#44x


Kyle#44x

1969 T100R Daytona
1979 Powroll Honda XR250 "Dallas Baker" flattracker
1975 XL350 project bike
Re: BSA B50 / Porsche 911 top ends? #210141
07/02/08 5:15 pm
07/02/08 5:15 pm
Joined: Jan 2006
Posts: 6,751
Laredo (South) Texas, USA
GrandPaul Online content
BritBike Forum member
GrandPaul  Online Content
BritBike Forum member
Joined: Jan 2006
Posts: 6,751
Laredo (South) Texas, USA
Why not just slap the whole Porsche top end on the BSA cases? Just need to fab up the pushrod tube; maybe use a Triumph seal arrangement? hee hee


GrandPaul (does not use emoticons)
Author of the book "Old Bikes"
Too many bikes to list, mostly Triumph & Norton, some BSA & European
"The Iron in your blood should be Vintage"
Re: BSA B50 / Porsche 911 top ends? #210142
07/02/08 5:23 pm
07/02/08 5:23 pm
Joined: Sep 2002
Posts: 7,812
Seattle
Alex Offline

BritBike Forum member
Alex  Offline

BritBike Forum member
Joined: Sep 2002
Posts: 7,812
Seattle
Crazy. I love it.


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
Re: BSA B50 / Porsche 911 top ends? #210143
07/03/08 6:29 pm
07/03/08 6:29 pm
Joined: Oct 2005
Posts: 59
Ohio
A
Adam Offline
BritBike Forum member
Adam  Offline
BritBike Forum member
A
Joined: Oct 2005
Posts: 59
Ohio
What year/model of 911 cylinder are you using? What's the bore?

Re: BSA B50 / Porsche 911 top ends? #210144
07/03/08 7:02 pm
07/03/08 7:02 pm
Joined: Jun 2004
Posts: 1,115
Kansas
kboyd Offline OP
BritBike Forum member
kboyd  Offline OP
BritBike Forum member
Joined: Jun 2004
Posts: 1,115
Kansas
I just passed this one on...

http://www.flattrack.com/index.php?optio...184&catid=3

Kyle#44x


Kyle#44x

1969 T100R Daytona
1979 Powroll Honda XR250 "Dallas Baker" flattracker
1975 XL350 project bike
Re: BSA B50 / Porsche 911 top ends? #210145
07/03/08 11:53 pm
07/03/08 11:53 pm
Joined: May 2006
Posts: 150
Raleigh NC
Damon Fever Offline
Life member
Damon Fever  Offline
Life member
Joined: May 2006
Posts: 150
Raleigh NC
That's Stan Millard, builder of some of the fastest B50 trackers to ever turn a wheel. Mike Gilkey got third place in an AMA Pro 600 race (not a vintage race) on Stan's B50 a few years ago.

Cheers
Rick F

Re: BSA B50 / Porsche 911 top ends? #210146
07/04/08 4:18 am
07/04/08 4:18 am
Joined: Aug 2001
Posts: 1,105
Kansas City, USA
J in KC Offline
BritBike Forum member
J in KC  Offline
BritBike Forum member
Joined: Aug 2001
Posts: 1,105
Kansas City, USA
Examples of Stan's work.


Re: BSA B50 / Porsche 911 top ends? #210147
07/04/08 7:25 pm
07/04/08 7:25 pm
Joined: Aug 2001
Posts: 1,875
California
Ron - in California R.I.P. Offline
In Remembrance
Ron - in California R.I.P.  Offline
In Remembrance
Joined: Aug 2001
Posts: 1,875
California
Yes, when I went to make up Goldie pistons, a North West Porche guy and I exchanged design info. This was a big help..! The major US based piston makers do not know that much about air coolded engines, and yes there are some critical design difference between the two..! So far, I have NOT had any piston failures with the changes that I made. In fact the pistons are bullet proof, yet a lot lighter than stock. A good design helps..! (The BSA pre-unit singles do have a significant engine weight advantage over the pre-units...)

Singles still rule (at times)...!

Cheers..!!

Ron

Re: BSA B50 / Porsche 911 top ends? #210148
07/06/08 3:57 pm
07/06/08 3:57 pm
Joined: Jan 2004
Posts: 3,569
ca, us
D
DMadigan Online content
BritBike Forum member
DMadigan  Online Content
BritBike Forum member
D
Joined: Jan 2004
Posts: 3,569
ca, us
It is probably the 2.4L of '72/'73 with an 85mm bore, 70.4mm stroke. The wrist pins are much larger then the B50, 19mm I believe. These pistons have an internal steel band cast into the top of the skirt to control distortion when hot. You could also use the 2.8L alloy barrels with Nikasil coating if you wanted to cheat a bit.

Re: BSA B50 / Porsche 911 top ends? #210149
07/06/08 5:54 pm
07/06/08 5:54 pm
Joined: Aug 2001
Posts: 1,875
California
Ron - in California R.I.P. Offline
In Remembrance
Ron - in California R.I.P.  Offline
In Remembrance
Joined: Aug 2001
Posts: 1,875
California
Me again... Being as I am home sick with a summer cold.. I am cleaning up my puter.. Found the link to the Porche guys I was talking about. These guys KNOW their stuff... and lo and behold they have a nice article on fuel.. You may know all of this, but still it is good reading..! Perhaps this link should be posted where the street guys can read it as well..?

http://www.rennsportsystems.com/~porsche/2a.html

Cheers..!!

Ron -sneeze, cough, etc...

Re: BSA B50 / Porsche 911 top ends? #210150
07/07/08 12:13 pm
07/07/08 12:13 pm
Joined: Oct 2004
Posts: 4,429
Melbourne Australia
Tiger Offline
BritBike Forum member
Tiger  Offline
BritBike Forum member
Joined: Oct 2004
Posts: 4,429
Melbourne Australia
One of the street guys just did Ron, most impressed. bigt


1969 TR6R
7.62 x 51 is not a maths puzzle.
Re: BSA B50 / Porsche 911 top ends? #210151
07/07/08 4:09 pm
07/07/08 4:09 pm
Joined: Aug 2001
Posts: 3,913
Houston Texas
Britbodger R.I.P. Offline
In Remembrance
Britbodger R.I.P.  Offline
In Remembrance
Joined: Aug 2001
Posts: 3,913
Houston Texas
Thanks for the article Ron. As you say - very good reading with much of it applicable to Triumph motorcycle engines.

BTW, I passed it on to a 911 Porsch owner here at work. It has answered quite a few outstanding questions that he had.

beerchug


Moderated by  Allan Gill 


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