Britbike forum

Classic British Spares Klempf British PartsBaxter Cycle BritBike Sponsor SteadfastCyclesSRM Engineering Lucas Classic Motorcycle Industrial tec supply Hepolite Pistons The Bonneville ShopLowbrow Customs

Upgrade your membership to: Premium Membership | Gold Membership | Life Membership | Vendor Membership | Site Sponsor Membership
Member Spotlight
Ron T. in KY
Ron T. in KY
Northern KY
Posts: 414
Joined: August 2001
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Top Posters(30 Days)
quinten 94
Rohan 64
Top Likes Received (30 Days)
quinten 14
Newest Members
Gearhard, yornocT120R, robert wilby, Jonah A, paulski
11,838 Registered Users
Who's Online Now
5 members (Andy Higham, Tigernuts, Morgan aka admin, Hillbilly bike, TrophyTR6), 30 guests, and 76 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Joined: Oct 2020
Posts: 145
Likes: 7
S
S-NJ-W Offline OP
Britbike forum member
OP Offline
Britbike forum member
S
Joined: Oct 2020
Posts: 145
Likes: 7
The front most rocker box cover thread that holds the stud into the head of my '72 A65 is stripped.
However the head is NOT the original head. It's pre OIF modifications, maybe 1966.

The thread I mean is the one that holds part number 65-0876.
Looks like it was originally tapped 1/4" British Standard Cycle - 26 TPI.

Any advice on how to deal with it? I am guessing that BSC helicoils might be hard to find.
Has anyone re-threaded the rocker box stud drillings in the cylinder head ?

Thanks for the help.

Steve.

BSA on eBay
Joined: May 2013
Posts: 8,194
Likes: 182
A
Britbike forum member
Offline
Britbike forum member
A
Joined: May 2013
Posts: 8,194
Likes: 182
Originally Posted by S-NJ-W
The front most rocker box cover thread that holds the stud into the head of my '72 A65 is stripped.
However the head is NOT the original head. It's pre OIF modifications, maybe 1966.

The thread I mean is the one that holds part number 65-0876.
Looks like it was originally tapped 1/4" British Standard Cycle - 26 TPI.

Any advice on how to deal with it? I am guessing that BSC helicoils might be hard to find.
Has anyone re-threaded the rocker box stud drillings in the cylinder head ?

Thanks for the help.

Steve.

I’ve helicoiled one of my heads to 1/4 BSF (also 26tpi) then instead of a stud used a BSF bolt.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (now rebuilt)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Joined: Dec 2002
Posts: 3,372
Likes: 36
L
Britbike forum member
Offline
Britbike forum member
L
Joined: Dec 2002
Posts: 3,372
Likes: 36
Lotta bikes running around with some JB Weld in that hole.

Joined: Oct 2009
Posts: 630
Likes: 19
P
Britbike forum member
Offline
Britbike forum member
P
Joined: Oct 2009
Posts: 630
Likes: 19
I have one that I used 6mm helicoils. Good fix and a bit smaller od than 1/4. PRT

Joined: Oct 2020
Posts: 145
Likes: 7
S
S-NJ-W Offline OP
Britbike forum member
OP Offline
Britbike forum member
S
Joined: Oct 2020
Posts: 145
Likes: 7
Thank you for the suggestions. There is enough 'meat' around the stripped hole to run a drill into it and re-tap it.
I guess I will run it through with a number 7 drill and see if it will hold a 1/4 UNC tap. If not, then a 5/16th F. I think
it's likely to be the latter. So I will wind up with a head with one thread as 5/16th UNC and the rest 1/4 BSC. That
kinda stuff really messes with my OCD. smile

Joined: Aug 2001
Posts: 5,645
Likes: 76
M
Britbike forum member
Offline
Britbike forum member
M
Joined: Aug 2001
Posts: 5,645
Likes: 76
If you still want to indulge your OCD, I'm pretty sure British Tools and Fasteners has BSC Heal-a-Coils.


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Joined: Oct 2020
Posts: 145
Likes: 7
S
S-NJ-W Offline OP
Britbike forum member
OP Offline
Britbike forum member
S
Joined: Oct 2020
Posts: 145
Likes: 7
Originally Posted by Mark Z
If you still want to indulge your OCD, I'm pretty sure British Tools and Fasteners has BSC Heal-a-Coils.

For the BSC Helicoils, no 1/4" items listed.

However, on BSC-CEI listings, they do have 1/4".
What's the difference between BSC and BSC-CEI ?

Joined: Sep 2004
Posts: 1,677
Likes: 151
Britbike forum member
Offline
Britbike forum member
Joined: Sep 2004
Posts: 1,677
Likes: 151
I've done quite a few recoils on BSA rocker boxes using M6, BSC and other threads and replaced the original studs with socket caps.


Unless youre worried about originality I simply use whatever is easily available, which in my case is M6.


Whatever you do end up using will be an improvement on the original as recoils are much stronger.


1968 A65 Firebird
1967 B44 Shooting Star
1972 Norton Commando
Joined: May 2016
Posts: 46
Likes: 1
S
Britbike forum member
Offline
Britbike forum member
S
Joined: May 2016
Posts: 46
Likes: 1
They are Both
the same. British Standard Cycle and Cycle Engineering industry if memory serves.

Joined: Oct 2001
Posts: 583
Likes: 7
O
Ola Offline
Britbike forum member
Offline
Britbike forum member
O
Joined: Oct 2001
Posts: 583
Likes: 7
As a 72, you should use sturdy 5/16" bolts/studs, due to the "head steady stay" between the rocker box cover and the frame. You do have the cover fitted for this, I hope. As far as I remember, oif covers do not go very well with earlier heads.

Regards

Last edited by Ola; 02/09/21 6:39 pm.

There are no bosses in a technical discussion
(Doug Hele, 1919 - 2001)
Joined: Oct 2020
Posts: 145
Likes: 7
S
S-NJ-W Offline OP
Britbike forum member
OP Offline
Britbike forum member
S
Joined: Oct 2020
Posts: 145
Likes: 7
Thanks for the comment Ola and you would be right if the bike still had the single carb head on it that it left the factory with. The previous owner swapped the OIF head for a 66-68 twin carb 'small port' head and just forgot about the head steady. The rocker cover is correct for the earlier head. It's just the one thread that's stripped.

Also thanks Stan about BSC and CEI being the same at 26 tpi. Brit tools and Fasteners says on one of it's pages that BSC and CEI are the same, but they prefer to use BSC, or something like that.

Looks like I will be getting a helicoil to keep the OCD daemons at bay.. It's my own fault, I know..

Joined: May 2013
Posts: 8,194
Likes: 182
A
Britbike forum member
Offline
Britbike forum member
A
Joined: May 2013
Posts: 8,194
Likes: 182
I wouldn’t go any bigger than 1/4, you have a small area on the rocker box that you have to try and seal.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (now rebuilt)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

1 member likes this: gavin eisler
Joined: Feb 2008
Posts: 5,729
Likes: 289
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2008
Posts: 5,729
Likes: 289
If you can't get hold of 1/4" BSCY then 1/4" BSF is virtually identical (same tpi).
HTH

1 member likes this: Allan G
Joined: Oct 2020
Posts: 145
Likes: 7
S
S-NJ-W Offline OP
Britbike forum member
OP Offline
Britbike forum member
S
Joined: Oct 2020
Posts: 145
Likes: 7
BSF = 55 degree thread form.
BSCY = 60 degree thread form.

OCD twitch starts...

I guess I can put a BSF helicoil in the stripped thread, buy a 1/4" BSF tap and recut the rest of the threads and then switch to cap head allen screws for the entire rocker box (6x screws).

There isn't a lot of space with the early head on the OIF frame and it looks to me like I have to unscrew the studs from the head to remove the head in the first place, So, that might be the best thing. I think it was the required removal of the rockerbox studs to pull the head off that may have been the reason why the thread was stripped in the first place.

Joined: Aug 2001
Posts: 5,645
Likes: 76
M
Britbike forum member
Offline
Britbike forum member
M
Joined: Aug 2001
Posts: 5,645
Likes: 76
A side issue: You really should have some sort of head steady. Maybe you could work off the lug on the front of the cyl. head, and fab some sort of bracket off the frame downtubes.


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Joined: Feb 2008
Posts: 5,729
Likes: 289
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2008
Posts: 5,729
Likes: 289
Low OCD threshold IMHO.

Joined: Oct 2020
Posts: 145
Likes: 7
S
S-NJ-W Offline OP
Britbike forum member
OP Offline
Britbike forum member
S
Joined: Oct 2020
Posts: 145
Likes: 7
Originally Posted by Mark Z
A side issue: You really should have some sort of head steady. Maybe you could work off the lug on the front of the cyl. head, and fab some sort of bracket off the frame downtubes.

Yes, I agree. I have been looking at the bracket welded to the frame under the steering head that the horn was screwed into and wondering if I can fab a 'rod' from that bracket to the drilled lug on the head. The angles are weird.

Originally Posted by Tridentman
Low OCD threshold IMHO.

Celebrate diversity.

Joined: Feb 2008
Posts: 5,729
Likes: 289
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2008
Posts: 5,729
Likes: 289
Agreed!

Joined: Aug 2001
Posts: 5,645
Likes: 76
M
Britbike forum member
Offline
Britbike forum member
M
Joined: Aug 2001
Posts: 5,645
Likes: 76
Originally Posted by S-NJ-W
Originally Posted by Mark Z
A side issue: You really should have some sort of head steady. Maybe you could work off the lug on the front of the cyl. head, and fab some sort of bracket off the frame downtubes.

Yes, I agree. I have been looking at the bracket welded to the frame under the steering head that the horn was screwed into and wondering if I can fab a 'rod' from that bracket to the drilled lug on the head. The angles are weird.

Yes, if you don't have a horn mounted there, that offers possibilities. FWIW, I've found that you can flatten the ends of tube steel without heating it. Then you can drill and angle the ends however you like. When my A65 bitsa was in a hardtail frame, I made the rear fender stays that way. Then perhaps a flat "U" bracket coming down from the horn lugs... or something like that.


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.

Moderated by  Allan G, Jon W. Whitley 

Link Copied to Clipboard
Job CycleBritish Cycle SupplyMorries PlaceKlempf British PartsPodtronicVintage MagazineBSA Unit SinglesBritBike SponsorBritish Tools & FastenersBritBike SponsorBritBike Sponsor






© 1996-2021 britbike.com
Powered by UBB.threads™ PHP Forum Software 7.7.5