Britbike forum

Classic British SparesKlempf British PartsBaxter CycleBritBike Sponsor SteadfastCyclesThe Bonneville ShopLowbrow CustomsGirling Classic MotorcycleLucas Classic MotorcycleHepolite PistonsIndustrial tec supply

Upgrade Your membership! Premium Membership Gold Membership Vendor Membership

New Sponsor post
5% Off Everything for Brit Bike Users
by The Bonneville Shop - 12/30/21 4:54 pm
New FAQ post
Manuals on DVD - Buy 4 for 3
All 4 DVD Manual
Member Spotlight
Bikeosaurus
Bikeosaurus
Canberra, Australia
Posts: 80
Joined: April 2018
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Top Posters(30 Days)
Cyborg 69
reverb 63
Top Likes Received (30 Days)
Cyborg 17
Newest Members
Sinner66, DucatiPete, mk31755, MAM, Jonez69
11,977 Registered Users
Who's Online Now
11 members (1971tr6, Steve Erickson, Falcon_52, Blown Income, Ted Sn, L.A.B., gunner, Kent Shaun, Spitfire Ken, Hank, Hugh Jörgen), 33 guests, and 18 robots.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums35
Topics75,253
Posts757,980
Members11,977
Most Online14,755
May 5th, 2019
Previous Thread
Next Thread
Print Thread
Page 1 of 2 1 2
#857445 09/01/21 10:00 am
Joined: Oct 2012
Posts: 6,144
Likes: 210
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 6,144
Likes: 210
My A10 build from a pile of unrelated parts has been on the road for a few months. It has a persistent rocker box oil leak, later alloy head. Rocker boxes have been on an off many times. Two different heads and two rocker boxes.All parts have been checked for fit using machinist straight edge and .001 feeler gauge between the joints. Paper type gaskets, sealer only and .028 thick soft copper gaskets...All leaked from the same areas.
Then on the A10 website a few suggested the top mount secured to the rocker hold down bolts can cause fretting between the head and box causing leaks. I leave off the top mount, annealed copper gaskets....No Leaks!!.....
But....this is a smooth running engine for a 650 twin.... leaving off the mount has made a noticeable increase in engine vibration....
So...any suggestions on how to fix this problem..?


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
British motorcycles on eBay
Joined: May 2013
Posts: 8,336
Likes: 207
A
Britbike forum member
Offline
Britbike forum member
A
Joined: May 2013
Posts: 8,336
Likes: 207
What sealer have you used?

My dad has a few A10's I never found his to leak, he just used the paper gaskets and welseal. I've never known any high frequency vibration like you'd get from the A65 either.


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: Feb 2008
Posts: 5,856
Likes: 341
Britbike forum member
Online Content
Britbike forum member
Joined: Feb 2008
Posts: 5,856
Likes: 341
Hi Tony— nothing very helpful to add I am afraid but—-
Back in the day I had two A10s— both with sidecars and both had a hard life.
Now I have a A7 Shooting Star— same basic design as the A10.
Getting a good seal at that point is difficult as you have to make sure that the tops of the pushrods are properly engaged in the rockers.
BSA made a special tool— a comb— to do this but I have never had much success with this.
I have long fingers and could put a finger in the rocker box while standing astride the bike and feel the pushrod tops into position as I lowered the rocker box into position.
IME it is easy to disturb the rocker box gasket sealant and the gasket itself while getting the pushrods into the rocker ends.
I have always used paper gaskets with a smear of Hylomar and achieved good oil tight joints.
HTH

1 member likes this: Allan G
Joined: Sep 2004
Posts: 1,787
Likes: 172
Britbike forum member
Online Content
Britbike forum member
Joined: Sep 2004
Posts: 1,787
Likes: 172
I've never owned an A10 so cant really comment with any authority, however I've a couple of thoughts which may help:-
- have you tried countersinking the threads in the head where the rocker box bolts presumably screw in? It may be that the area around the bolt hole and flange is getting pulled up slightly with the head steady attached, hence the leaks.
- maybe worth using thread inserts in the head rocker bolt holes, these should allow the securing bolts to be tightened a bit more without fear of stripping, thereby preventing leaks.


1968 A65 Firebird
1967 B44 Shooting Star
1972 Norton Commando
Joined: Oct 2012
Posts: 6,144
Likes: 210
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 6,144
Likes: 210
Paper gaskets have been been used with Gascinch as a sealer,,,,The paper gaskets just crumble after a while from the fretting .As mentioned ,the head and box tighten up with no gaps that i can see or measure. The stock alloy head has inserts for the rocker box bolts and don't move when the bolts re tightened







.


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Sep 2004
Posts: 1,787
Likes: 172
Britbike forum member
Online Content
Britbike forum member
Joined: Sep 2004
Posts: 1,787
Likes: 172
When you say fretting, do you mean sliding backwards and forwards or up and down?

My B44 rocker box and head has two hollow dowels through which a couple of the mounting studs are fitted. This prevents any fretting backwards and forwards which could occur since the rocker box is also attached to the head steady.

I dont know if the A10 had a similar arrangement, if not then maybe something similar could be fitted to prevent backwards and forwards fretting?


1968 A65 Firebird
1967 B44 Shooting Star
1972 Norton Commando
Joined: Aug 2015
Posts: 1,842
Likes: 65
A
Britbike forum member
Offline
Britbike forum member
A
Joined: Aug 2015
Posts: 1,842
Likes: 65
Don't be tempted to do many miles with the head steady removed. The down tubes will crack just above the top front forged lugs. Don't ask me how I know this


BSA B31 500 "Stargazer"
Greeves 200 "Blue Meanie"
Greeves 350
Greeves 360
GM500 sprint bike "Deofol"
Rickman Jawa 500 "Llareggub"
Aprilia RSV Mille "Lo Stregone"
'35 & '36 OK Supreme
Kawasaki ZZR1400 "Kuro no senshi"
Joined: Feb 2019
Posts: 767
Likes: 259
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2019
Posts: 767
Likes: 259
Originally Posted by Hillbilly bike
My A10 .....has a persistent rocker box oil leak........any suggestions on how to fix this problem..?
I'm suspicious of those bronze thread inserts these heads have.
[Linked Image from i.postimg.cc]
I don't know how they are held in (Threaded in or cast in?) but I have seen them sitting a bit proud of the gasket surface. This head is an example even though it doesn't really look like it in the photo.

So, what this could mean is that the thread bushing could be moving some when tightened, contacting the rocker box first, and preventing good clamping pressure on the rest of the gasket surface.
My plans for this particular head in the photo? Remove the guides (which need replacing anyway), find some BSF set screws (grub screws) to screw down into the thread bushings to jack them up to whatever height they may want to be at when the rocker box is torqued. Then surface them down to the level of the gasket surface on a surface plate with wet or dry sandpaper glued onto it.

I admit, this probably sounds extreme especially if your head just got new guides and valve seats but it would probably fix the oil leak.

Maybe you could do the grub screw thing, see how far up they sit (if at all) and then if necessary hand file the tall ones down to match the gasket surface.

Other more basic possibilities: Bolts too long, porosity, cracks, but I figure you already know about that sort of stuff.

Last edited by Stuart Kirk; 09/02/21 1:21 am. Reason: Thought of something else.
Joined: Oct 2012
Posts: 6,144
Likes: 210
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 6,144
Likes: 210
I have checked the insert fit several time with with the head bolted onto the cylinder. Not the problem ......and as mentioned, I used two heads and different rocker boxes and it still leaked.
This photo shows the 3 inch bolts that secure the top mount..On this head the original inserts have 5/16-24 Helicoils....

Dowels might be good around the four shorter perimeter studs. This would require precision work on my large drill press..I may not be able to do that....Finding a shop to do it for less than a king's ransom is a problem...

8D9269AF-D0CD-4FF7-B759-BCF5D56126D3.jpeg

79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Feb 2019
Posts: 767
Likes: 259
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2019
Posts: 767
Likes: 259
Originally Posted by Hillbilly bike
I have checked the insert fit several time with with the head bolted onto the cylinder. Not the problem ......and as mentioned, I used two heads and different rocker boxes and it still leaked. ...
Then I guess the only other suggestion I have to offer is that you resurface the rocker box and the top of the head on a surface plate to be sure they both are absolutely flat. This is something I generally do routinely and you may already have. It's surprising just how warped or poorly machined some of this old stuff is.

Joined: Oct 2012
Posts: 6,144
Likes: 210
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 6,144
Likes: 210
Originally Posted by Stuart Kirk
Originally Posted by Hillbilly bike
I have checked the insert fit several time with with the head bolted onto the cylinder. Not the problem ......and as mentioned, I used two heads and different rocker boxes and it still leaked. ...
Then I guess the only other suggestion I have to offer is that you resurface the rocker box and the top of the head on a surface plate to be sure they both are absolutely flat. This is something I generally do routinely and you may already have. It's surprising just how warped or poorly machined some of this old stuff is.
That has been done...and with the head torqued on the bike, rocker box and bolts in place, ,using a .001 feeler gauge, tighten the box and try to pull out the feeler in as many locations as possible..no gaps to be found...Two heads ,two rocker boxes same leaks......The are paranormal events going on here...


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Sep 2008
Posts: 867
Likes: 11
Britbike forum member
Online Content
Britbike forum member
Joined: Sep 2008
Posts: 867
Likes: 11
Tony,

I have always used the standard gaskets you purchase from Baxters, BCS, etc. w/o issue along with some Gascinch as well. My option, the paper gaskets are too thin leading to leaks.


1955 BSA Bantam D1 Plunger
1956 BSA A10RR Street and LSR Bike
1961 BSA C15S
1966 BSA spitfire
1969 Triumph T100C
1970 Triumph TR6R
1970 Triumph TR6C
1972 BSA Lightning LSR Bike
1974 Triumph T150V
Joined: Aug 2001
Posts: 3,335
Likes: 143
Britbike forum member
Offline
Britbike forum member
Joined: Aug 2001
Posts: 3,335
Likes: 143
In 25 years of trying I've never been able to fully seal my rocker boxes. Like Mr Hillbilly I've tried every solution except the alloy gaskets including different head and rocker box, resurfacing the joint area and countersinking the threaded inserts, thicker gaskets, and anerobic sealant. I remember reading something about the top motor mounts being the culprit in another forum but never felt the need to find out as the leak is small enough to not make too much of a mess so I just clean it every so often and ignore it. The only person who ever told me he had no leaks at all was running an iron head. Don't know what bearing that might have but there it is.
FWIW
MikeG


1960 BSA A10
2007 Suzuki Bandit
1957 A10
(Used to be a Triumph here)
71 Norton Commando
17 Triumph Bonneville

Joined: Sep 2006
Posts: 182
Likes: 1
M
Britbike forum member
Offline
Britbike forum member
M
Joined: Sep 2006
Posts: 182
Likes: 1
Does it do it when cold or hot ? if hot could be the dilatation acting against the head steady ( sorry I am a Norton guy) never own a beesa twin, but ...

Joined: Feb 2019
Posts: 767
Likes: 259
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2019
Posts: 767
Likes: 259
Originally Posted by Hillbilly bike
...Two heads ,two rocker boxes same leaks......The are paranormal events going on here...
Originally Posted by MikeG
In 25 years of trying I've never been able to fully seal my rocker boxes. Like Mr Hillbilly I've tried every solution except the alloy gaskets...
I just talked to the tech guy at Cometic gaskets. They make an aluminum core gasket with a thin layer of dense sealing rubber foam on each side that work very well on difficult to seal applications. Mike in tech told me they had never made A10 rocker box gaskets but could do so easily and at reasonable cost. Maybe this is an option. The only possible issue is that they are somewhat thicker than most other paper or composite gaskets.

Joined: Sep 2006
Posts: 182
Likes: 1
M
Britbike forum member
Offline
Britbike forum member
M
Joined: Sep 2006
Posts: 182
Likes: 1
and in your first post you said , no mounts no leaks , so ...........is a rose joint possible to imagine or a clever guy (more than me !!) create a flexible mount !!!

Joined: Sep 2006
Posts: 182
Likes: 1
M
Britbike forum member
Offline
Britbike forum member
M
Joined: Sep 2006
Posts: 182
Likes: 1
https://www.a7a10.net/forum/index.php?topic=15233.0

jus to add to the conversation..............

Joined: Oct 2012
Posts: 6,144
Likes: 210
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 6,144
Likes: 210
Originally Posted by Blown Income
Tony,

I have always used the standard gaskets you purchase from Baxters, BCS, etc. w/o issue along with some Gascinch as well. My option, the paper gaskets are too thin leading to leaks.
The gaskets you mention and Gascinch was my original choice...They leaked with 15 minutes... Th gaskets were actually shredded , a sure indication of fretting....
.....
Originally Posted by Stuart Kirk
Originally Posted by Hillbilly bike
...Two heads ,two rocker boxes same leaks......The are paranormal events going on here...
Originally Posted by MikeG
In 25 years of trying I've never been able to fully seal my rocker boxes. Like Mr Hillbilly I've tried every solution except the alloy gaskets...
I just talked to the tech guy at Cometic gaskets. They make an aluminum core gasket with a thin layer of dense sealing rubber foam on each side that work very well on difficult to seal applications. Mike in tech told me they had never made A10 rocker box gaskets but could do so easily and at reasonable cost. Maybe this is an option. The only possible issue is that they are somewhat thicker than most other paper or composite gaskets.
I will call Cometic, do you remember who you talked to ?....the stock non paper gaskets and the copper ones are.028 thick...I built an alloy head swing arm A10 20 years ago. I sealed the rocker box with a thin smear of RTV and stock top mount,no leaks.....


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Feb 2019
Posts: 767
Likes: 259
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2019
Posts: 767
Likes: 259
Originally Posted by Hillbilly bike
........I will call Cometic, do you remember who you talked to ?.........
I talked to Mike Sauer in tech. He was very helpful and took the time to really dig into their inventory system while I was on the phone but didn't find rocker box gaskets even though he said they do make A10 head, base and tappet cover gaskets already. Odd.
He said to send good examples of the actual gaskets or take paper and make a rubbing of the surface where the gasket goes and MAIL it to them.
Emails, faxes and such aren't accurate enough.
Send to:
Mike Sauer
8090 Auburn Road
Concord, OH 44077

Tech line: 440-354-0777

It will take a few weeks but will be interesting to see if it works out.

Joined: Oct 2012
Posts: 6,144
Likes: 210
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 6,144
Likes: 210
Originally Posted by Stuart Kirk
Originally Posted by Hillbilly bike
........I will call Cometic, do you remember who you talked to ?.........
I talked to Mike Sauer in tech. He was very helpful and took the time to really dig into their inventory system while I was on the phone but didn't find rocker box gaskets even though he said they do make A10 head, base and tappet cover gaskets already. Odd.
He said to send good examples of the actual gaskets or take paper and make a rubbing of the surface where the gasket goes and MAIL it to them.
Emails, faxes and such aren't accurate enough.
Send to:
Mike Sauer
8090 Auburn Road
Concord, OH 44077

Tech line: 440-354-0777
It will take a few weeks but will be interesting to see if it works out.
Thank you...I have some unused gaskets to send in..


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Aug 2001
Posts: 3,335
Likes: 143
Britbike forum member
Offline
Britbike forum member
Joined: Aug 2001
Posts: 3,335
Likes: 143
Originally Posted by Hillbilly bike
Originally Posted by Stuart Kirk
Originally Posted by Hillbilly bike
........I will call Cometic, do you remember who you talked to ?.........
I talked to Mike Sauer in tech. He was very helpful and took the time to really dig into their inventory system while I was on the phone but didn't find rocker box gaskets even though he said they do make A10 head, base and tappet cover gaskets already. Odd.
He said to send good examples of the actual gaskets or take paper and make a rubbing of the surface where the gasket goes and MAIL it to them.
Emails, faxes and such aren't accurate enough.
Send to:
Mike Sauer
8090 Auburn Road
Concord, OH 44077

Tech line: 440-354-0777
It will take a few weeks but will be interesting to see if it works out.
Thank you...I have some unused gaskets to send in..


Please keep us informed on this. I would spring for a set if they want to make a run of them.


1960 BSA A10
2007 Suzuki Bandit
1957 A10
(Used to be a Triumph here)
71 Norton Commando
17 Triumph Bonneville

Joined: Oct 2012
Posts: 6,144
Likes: 210
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 6,144
Likes: 210
Ok I will, the sample gaskets and cover note is in the mail box


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
1 member likes this: MikeG
Joined: Sep 2004
Posts: 1,787
Likes: 172
Britbike forum member
Online Content
Britbike forum member
Joined: Sep 2004
Posts: 1,787
Likes: 172
There's more details on fixing the A10 rocker leaks on the A7A10 Forum, see This Link.

A couple of methods mentioned in the link above are:-
- making up a gasket using Siliconised Glass Cloth, a material used for insulating and capable of high temp use. The new gasket is cut-out based on the shape of a paper gasket and thinly smeared with RTV silicon both sides before fitting, its allowed to cure for a while before fully bolting down.
- making a kind of rubber buffer in the head steady bracket, this helps absorb any movement transmitted between the head and frame. The rubber is held in a tube with the tube attached to a bracket on the frame. A bolt runs through the centre of the rubber and the ends of the bolt attach to brackets which attach to the rocker box.

The source of the problem seems to be lateral transmission of of movement between head and frame so although hollow dowels may be impractical perhaps another way is to sleeve the holes in the rocker box which house the mounting bolts. The sleeves could be made from steel and slightly larger than the existing hole, they would need to be pressed in. The id of the sleeve would closely match the od of the bolt to prevent any movement. To aid fitting of the bolts, the end of the thread could be ground into a taper.


1968 A65 Firebird
1967 B44 Shooting Star
1972 Norton Commando
Joined: Oct 2012
Posts: 6,144
Likes: 210
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 6,144
Likes: 210
Yes, I saw those comments on the A10 forum.....I don't understand how the rubber mount does any good...It would allow the frame and rocker box to move relative to each other,...No different than removing the top mount ?
The rocker box has 8 Fasteners, 4 shorter studs on the perimeter and the 4 3-1/2 inch bolts in the center. Strange as it seems, this does not prevent fretting...My bike seems worse than others despite being a smooth runner and full contact between the rocker box and head mating surfaces....Too bad because the thing is an enjoyable ride...


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: May 2013
Posts: 8,336
Likes: 207
A
Britbike forum member
Offline
Britbike forum member
A
Joined: May 2013
Posts: 8,336
Likes: 207
Loctite 518 flange sealent might be worth a try.


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)

Page 1 of 2 1 2

Moderated by  Jon W. Whitley 

Link Copied to Clipboard
British Cycle SupplyMorries PlaceKlempf British PartsBSA Unit SinglesPodtronicVintage MagazineBritBike SponsorBritish Tools & FastenersBritBike Sponsor






© 1996-2022 britbike.com
Powered by UBB.threads™ PHP Forum Software 7.7.5