BritBike Forum logo
BritBike Sponsor BritBike Sponsor BritBike Sponsor
BritBike Sponsor

BritBike Sponsor

BritBike Sponsor
BritBike Sponsor BritBike Sponsor BritBike Sponsor
  JWood Auction  
Home | Sponsors, Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons, "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Photo posting tutorial

Member Spotlight
Doug Barisone
Doug Barisone
california, USA
Posts: 30
Joined: April 2009
Show All Member Profiles 
Shout Box
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Who's Online Now
211 registered members (57nortonmodel77), 1,665 guests, and 560 spiders.
Key: Admin, Global Mod, Mod
Newest Members
revans, Gilly, XTINCT, Bruce Roberts, Brian Ellery
9959 Registered Users
Top Posters(30 Days)
btour 191
koan58 99
Stuart 84
NickL 72
Popular Topics(Views)
438,413 mail-order LSR
Forum Statistics
Forums33
Topics65,287
Posts632,399
Members9,959
Most Online3,995
Feb 13th, 2017
Like BritBike.com on Facebook

Previous Thread
Next Thread
Print Thread
Rate This Thread
#381074 - 06/27/11 6:56 am Meriden Thruxton 650 engine spec  
Joined: Aug 2001
Posts: 1,081
Phatt Bob Offline
BritBike Forum member
Phatt Bob  Offline
BritBike Forum member

Joined: Aug 2001
Posts: 1,081
Cheshire UK
Hi all,
Does anyone have access to the engine spec for any of the factory Thruxtons made in the 60's. Info seems to be vague from the usual sources. I don't suppose there are any big secrets we haven't stumbled across already, but it would be nice to see them all in one place.

Looking for things like compression ratio, ignition timing etc. Service sheet 310 is OK so far as it goes for cams and followers etc but were any others fitted? Also to what extent was any lightening work carried out on the top and bottom ends? I once one had a "Thuxton" crank with a very narrow flywheel.

Any advice gratefully recieved.

Thanks and regards

Bob


Phatt Bob
'95 Daytona 1200
'98 Daytona 1200 dragbike
ex-850 T140 Caff Racer, 850 Triton, Morgo T120, Starfire and Pretend Daytona 500 owner
Support Your #1 BritBike Forum!
Membership Type! Free
Member
Premium
Member
Premium Life
Member
Vendor
Member
Site
Sponsor
Recognition No Premium Member Premium Life member (5 years) Vendor Member Site Sponsor Membership
Post commercial threads No No No Yes Yes
Custom title No Yes Yes Yes Yes
Upload avatar & photos No Yes Yes Yes Yes
Link avatar & photos Yes Yes Yes Yes Yes
Private Message Storage: 10 100 100 100 100
Length of signatures 255 600 600 600 600
Removes this very advert island between post 1&2 No Yes Yes Yes Yes
Price Free $12.90/year $105.00 No End
$55.00/5 years
$210.00/year
($17.50/month)
Email
Click on button >>
  Premium Member Premium Life member Vendor Member Site Sponsor Membership
#381076 - 06/27/11 8:03 am Re: Meriden Thruxton 650 engine spec [Re: Phatt Bob]  
Joined: Jul 2005
Posts: 603
6T Offline
BritBike Forum member
6T  Offline
BritBike Forum member

Joined: Jul 2005
Posts: 603
back down the 'smoke',England
..can't help much regarding internals,mines only done 500(none racing)miles but its got the morgo 750 kit & quaiffe 5 speed box..here's some photo's.Notice the pushrods that had not seated properly in the standard rockerboxes,more on that later(another thread)Cheers...

Last edited by 6T; 06/27/11 8:05 am.

...I do not and cannot accept the principal that incompetence justifies dismissal...
BMW R1100rt
6T 1965
T110 1958
#381082 - 06/27/11 9:58 am Re: Meriden Thruxton 650 engine spec [Re: Phatt Bob]  
Joined: May 2006
Posts: 509
76degree-triumph Offline
BritBike Forum member
76degree-triumph  Offline
BritBike Forum member

Joined: May 2006
Posts: 509
melbourne, australia
Gday Bob, years ago I bought a genuine Boyer race engine. Its fitted with the 3" radius followers but what was not mentioned in his book was the tube connecting the inlet followers to the exh to feed oil to the inlet side.



As I understand it the thruxton cams were part #E4220. These were also listed as T-Bird cams in 1961 or 62 for a short time. Ive got a set here but they have worn the nose off them.

This engine came with the "spitfire" cams, as per the Boyer book, not the 4220's.

Cam timing was IO 51 IC 72. EO 83 EC 47. All @.020".

I dropped those cams into my T140 road bike, it transformed it.

I have a 4220 cam on the inlet of my dirtbike but I cant find the timing events. It uses 'R' followers.
If you are interested I will try and dig them up.


1950 Speed Twin outfit
1951 Thunderbird outfit (76 degree racebike, or is it 90 deg now?)
1955 BSA D3 minibike outfit
Triumph solo's
#381088 - 06/27/11 10:39 am Re: Meriden Thruxton 650 engine spec [Re: 76degree-triumph]  
Joined: Aug 2001
Posts: 1,081
Phatt Bob Offline
BritBike Forum member
Phatt Bob  Offline
BritBike Forum member

Joined: Aug 2001
Posts: 1,081
Cheshire UK
Thanks 6T and 76degree-triumph, this is exactly the sort of info I'm looking for.

6T, those look like mushroom headed tappets. Do you know if they were an original fitment or aftermarket? Also polished and shimmed rockers as I would have expected.

76DT, I once owned a set of thruxton tappet blocks in alloy bronze IIRC, they were bigger and slot machined for the 3" tappets was wider in the front to back dimension, it's hard to tell from the photo, but are the tappets longer than the 3059s? Also are they dome headed or cupped at the other end. I was told that if you used the shorter 3059s with 4220s the leading edge would dig in. Never actually got chance to try it. I've got a 4220 also, but assumed if the block needed machining to fit a bigger guide block, T140 inlets would have been simpler.

Thanks again all.

Regards

Bob


Phatt Bob
'95 Daytona 1200
'98 Daytona 1200 dragbike
ex-850 T140 Caff Racer, 850 Triton, Morgo T120, Starfire and Pretend Daytona 500 owner
#381089 - 06/27/11 10:42 am Re: Meriden Thruxton 650 engine spec [Re: 76degree-triumph]  
Joined: Jul 2005
Posts: 603
6T Offline
BritBike Forum member
6T  Offline
BritBike Forum member

Joined: Jul 2005
Posts: 603
back down the 'smoke',England
...I see Morgo do the Thruxton tappet blocks but the barrels have to be machined!
http://www.morgo.co.uk/tappet.html


...I do not and cannot accept the principal that incompetence justifies dismissal...
BMW R1100rt
6T 1965
T110 1958
#381090 - 06/27/11 10:46 am Re: Meriden Thruxton 650 engine spec [Re: Phatt Bob]  
Joined: Jul 2005
Posts: 603
6T Offline
BritBike Forum member
6T  Offline
BritBike Forum member

Joined: Jul 2005
Posts: 603
back down the 'smoke',England
..I don't have special pushrods in mine but THINK the Thruston used triunph 250 ones moded?Have you got the Stan Shenton book?Cheers..


...I do not and cannot accept the principal that incompetence justifies dismissal...
BMW R1100rt
6T 1965
T110 1958
#381103 - 06/27/11 12:20 pm Re: Meriden Thruxton 650 engine spec [Re: 6T]  
Joined: Aug 2001
Posts: 1,081
Phatt Bob Offline
BritBike Forum member
Phatt Bob  Offline
BritBike Forum member

Joined: Aug 2001
Posts: 1,081
Cheshire UK
Hi mate, yes, I have got it, but until you mentioned I'd forgotten...its me age.

It shows the flywheel and tappets etc quite nicely, but I reckon both the cams it shows are the same profile......

The reason I ask this is that I have an acquaintance who has a "Thruxton Spec" 69 Bonneville. I'm beginning to wonder if "Thruxton Spec" is a bit variable apart from all cosmetic bits!

Cheers

Bob


Phatt Bob
'95 Daytona 1200
'98 Daytona 1200 dragbike
ex-850 T140 Caff Racer, 850 Triton, Morgo T120, Starfire and Pretend Daytona 500 owner
#381130 - 06/27/11 2:10 pm Re: Meriden Thruxton 650 engine spec [Re: Phatt Bob]  
Joined: Jul 2005
Posts: 603
6T Offline
BritBike Forum member
6T  Offline
BritBike Forum member

Joined: Jul 2005
Posts: 603
back down the 'smoke',England
..I remember the quip quite well.. Stan Shenton told his employees.. "The Thruxton Bonnevilles arrived!!" to which someone said "but its not a works Thruxton is it!".....


...I do not and cannot accept the principal that incompetence justifies dismissal...
BMW R1100rt
6T 1965
T110 1958
#381303 - 06/28/11 9:01 am Re: Meriden Thruxton 650 engine spec [Re: Phatt Bob]  
Joined: Jan 2007
Posts: 209
Trevor Stapp Offline
BritBike Forum member
Trevor Stapp  Offline
BritBike Forum member

Joined: Jan 2007
Posts: 209
New Zealand
Bob,

Check out http://www.hoppybikes.co.uk/
Talk to George Hopwood, great guy and wealth of infor.
Spannered back in teh 60's on Thruxtons.

Cheers,
Trev


66T100SR Cafe racer
59 T20 Cub
1938 - 53 5T Bitsa project, now a roller
Duplex frame under the bench
#381308 - 06/28/11 10:29 am Re: Meriden Thruxton 650 engine spec [Re: Phatt Bob]  
Joined: May 2006
Posts: 509
76degree-triumph Offline
BritBike Forum member
76degree-triumph  Offline
BritBike Forum member

Joined: May 2006
Posts: 509
melbourne, australia
Bob, Ive used the 4220 on the inlet for many years with 'R' followers with no probs or abnormal wear whatsoever. They are in a unit engine with a T140 topend and norton crank and rods.
STD T140 guide blocks.
The thruxton followers in the front to back dimension are around 1/8th longer then std or 'R'. They are in my 650 race engine at the moment so I cant measure them.
They are dome headed and although I have not measured the length the pushrods appear to be STD 650 items.
I hope this helps,
Chris.


1950 Speed Twin outfit
1951 Thunderbird outfit (76 degree racebike, or is it 90 deg now?)
1955 BSA D3 minibike outfit
Triumph solo's
#381487 - 06/29/11 7:13 am Re: Meriden Thruxton 650 engine spec [Re: 76degree-triumph]  
Joined: Aug 2001
Posts: 1,081
Phatt Bob Offline
BritBike Forum member
Phatt Bob  Offline
BritBike Forum member

Joined: Aug 2001
Posts: 1,081
Cheshire UK
Thanks again folks,

Grumpy Trevor,
Funnily enough, this IS one of George Hopwoods motors, with the 3" followers and Spitfire (E6897 and 8 or his version) cams not E4220s, but sold to my mate as a Thruxton spec motor. Hence my question about what the spec was. Cam timings are similar for inlet but not exhaust, so they're obviously different beasts.

When is a Thruxton not a Thruxton? Does it need to have Thruxton cams to be a Thruxton, or just the word from an authoratative figure (e.g. Hoppy) that it can be considered a Thruxton.
I'm beginning to suspect the answer......

Bob


Phatt Bob
'95 Daytona 1200
'98 Daytona 1200 dragbike
ex-850 T140 Caff Racer, 850 Triton, Morgo T120, Starfire and Pretend Daytona 500 owner
#404526 - 11/19/11 9:38 am Re: Meriden Thruxton 650 engine spec [Re: Phatt Bob]  
Joined: Nov 2011
Posts: 4
Steve69 Offline
BritBike Forum member
Steve69  Offline
BritBike Forum member

Joined: Nov 2011
Posts: 4
uk
I tahe a copy of the alternative parts list for the 1964 thruxtons
if anyone is interested I could scan it. I have nothing for the
later thruxtons though I'am afraid.

-Steve

#404595 - 11/19/11 7:54 pm Re: Meriden Thruxton 650 engine spec [Re: Phatt Bob]  
Joined: Jun 2007
Posts: 5,456
HawaiianTiger Online content
BritBike Forum member
HawaiianTiger  Online Content

BritBike Forum member

Joined: Jun 2007
Posts: 5,456
Maui Hawaii
When I was restoring my '62 6T I hunted the world wide for E4220/1 cams and came up short. No wonder. Only later did I discover that these cams were the same cams used in the Thruxton. They must be coveted by collectors and classic racers. I ended up installing T110 cams and was never satisfied.
E4220 cams are ramped cams and I'm sure by then folks were discovering that the ramps were easier on valve train components. I have saved my cams even though they were not usable in my engine having rusted too much. I would like to have them duplicated and use them in a street rod.
Bill

Last edited by HawaiianTiger; 11/19/11 7:54 pm.

Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
#404673 - 11/20/11 10:33 am Re: Meriden Thruxton 650 engine spec [Re: Phatt Bob]  
Joined: Jul 2005
Posts: 603
6T Offline
BritBike Forum member
6T  Offline
BritBike Forum member

Joined: Jul 2005
Posts: 603
back down the 'smoke',England
Hi Bill,look up "David Newman camshafts" of Orpington,Kent... He's refaced cam followers for me,very good service and reasonable price... It wouldn't be too expensive to ship your cams,would it? Cheers!


...I do not and cannot accept the principal that incompetence justifies dismissal...
BMW R1100rt
6T 1965
T110 1958

Moderated by  John Healy 


Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.373s Queries: 15 (0.033s) Memory: 0.8964 MB (Peak: 1.1278 MB) Zlib disabled. Server Time: 2017-11-23 01:45:50 UTC