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500 heads #754842
11/02/18 11:04 am
11/02/18 11:04 am
Joined: Jan 2006
Posts: 2,001
Asheville, NC
Mike Baker Offline OP
BritBike Forum member
Mike Baker  Offline OP
BritBike Forum member

Joined: Jan 2006
Posts: 2,001
Asheville, NC
There's a possibility of a 500 in the not too distant future. AHRMA has done some rule changes to where bearing motors and later frames are now allowed for classic 60's. All good IMO, as the new rules address reliability with the bushing and safety issues with the old style frame. They still spec a squish band head, though. My understanding is that one is stuck with a low compression motor with this head? Is there anything that could be done to later pistons to allow them to be used with the early head?
Thanks!

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Re: 500 heads [Re: Mike Baker] #754843
11/02/18 11:13 am
11/02/18 11:13 am
Joined: Aug 2015
Posts: 1,290
Bolton Lancs UK
A
Andy Higham Offline
BritBike Forum member
Andy Higham  Offline
BritBike Forum member
A

Joined: Aug 2015
Posts: 1,290
Bolton Lancs UK
Maybe if you were more precise you may get some answers, at least make and model
A "500" could be about anything, Just about every manufacturer made a 500.


BSA B31 500cc "Stargazer"
Greeves 200cc "Blue Meanie"
Greeves 350
Greeves 360 Challenger
Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500cc sprint/LSR bike "Deofol"
Jawa 500cc "Llareggub"
2003 Aprilia RSV Mille "Lo Stregone"
'35 OK Supreme
'36 OK Supreme
Re: 500 heads [Re: Mike Baker] #754847
11/02/18 11:42 am
11/02/18 11:42 am
Joined: Jan 2006
Posts: 2,001
Asheville, NC
Mike Baker Offline OP
BritBike Forum member
Mike Baker  Offline OP
BritBike Forum member

Joined: Jan 2006
Posts: 2,001
Asheville, NC
Triumph

Re: 500 heads [Re: Mike Baker] #754854
11/02/18 3:15 pm
11/02/18 3:15 pm
Joined: Mar 2005
Posts: 10,236
Boston, Massachusetts
J
John Healy Online content
BritBike Forum member
John Healy  Online Content
BritBike Forum member
J

Joined: Mar 2005
Posts: 10,236
Boston, Massachusetts
[Linked Image]

[Linked Image]

The pistons are blanks that need to be machined to match squish band. They are made by Aries. In different configurations we used these for years.

These can be cut to make up to 13:1 compression ratio.

Head - Oversize intake plus .060"; stock exhaust.

Ports to match rider ability and type of racing. AHRMA 6 - 8 lap racing doesn't work with close ration gearing so looking for more torque than raw hp.

Because of the valve angle of the squish band head, the faces of the valves need to be faced to
provide clearance at valve overlap.

Valve springs are a problem. R&D last only one, maybe two, race meetings as the bike needs to be run up to 9,000rpm
to make any use able torque/hp. Stock crankshafts have problems when you actually find some hp,

When you are lucky enough to find some real power crankshafts become a problem. Even Nourish cranks will break, but not as much as stock.

When you find some power the transmission main shaft kick starter bearing housing (bearing retaining circlip arrangement) needs to be modified to keep it from coming out of third.


Re: 500 heads [Re: Mike Baker] #754940
11/03/18 11:42 am
11/03/18 11:42 am
Joined: Jan 2006
Posts: 2,001
Asheville, NC
Mike Baker Offline OP
BritBike Forum member
Mike Baker  Offline OP
BritBike Forum member

Joined: Jan 2006
Posts: 2,001
Asheville, NC
Thanks, J. I'm certain an incredible amount of time and effort went into development of your 500's. What class(s) did you run the bike in? How competitive was it vs. the big Nortons et c? The edges on those valves look like they'd be pretty thin!
I'm not looking to go the 10/10's route. Rather something that can be raced for a season with basic maintenance. I suppose those Arias can be cut to a 10-11 compression ratio as easily as 13. Not cheap but do able. But nothing to be done with stock units? Or any other more or less off the shelf pistons?
Thanks for any ideas

Last edited by Mike Baker; 11/03/18 11:45 am.
Re: 500 heads [Re: Mike Baker] #755357
11/07/18 9:36 pm
11/07/18 9:36 pm
Joined: Mar 2009
Posts: 95
manchester england
W
wilksville Offline

BritBike Forum member
wilksville  Offline

BritBike Forum member
W

Joined: Mar 2009
Posts: 95
manchester england
Mr Healey,
Q1, is the head pictured above an E3991 casting ?
Q2, are rockerboxes interchangeable between years where the valve angle changed ?
Regard Peter


'74 T140V,'83 XR1000, C&J FLATTRACKER T140,

Moderated by  Allan Gill 


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