BritBike Forum logo
BritBike Sponsor BritBike Sponsor BritBike Sponsor
BritBike Sponsor

BritBike Sponsor

BritBike Sponsor
BritBike Sponsor BritBike Sponsor BritBike Sponsor
The Bonneville Shop JRC Engineering dealers
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
Member Spotlight
furymalc
furymalc
northern B.C.Canada
Posts: 127
Joined: February 2012
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
29 registered members (AngloBike), 305 guests, and 387 spiders.
Key: Admin, Global Mod, Mod
Newest Members
Gregg's Atv, T160vUK, Dadstoys, Carlo D'Angelo, butcherboy
10443 Registered Users
Top Posters(30 Days)
NickL 68
franko 60
Popular Topics(Views)
730,122 mail-order LSR
Forum Statistics
Forums34
Topics68,538
Posts667,373
Members10,443
Most Online3,995
Feb 13th, 2017
Like BritBike.com on Facebook

Previous Thread
Next Thread
Print Thread
Rate Thread
850 RH10 Stage one head #741807
07/14/18 12:32 am
07/14/18 12:32 am
Joined: Jun 2007
Posts: 6,082
Maui Hawaii
HawaiianTiger Online content OP
BritBike Forum member
HawaiianTiger  Online Content OP
BritBike Forum member

Joined: Jun 2007
Posts: 6,082
Maui Hawaii
This is a head off my '74 850. I replaced it with a standard head about 8 years ago due to the fact I wanted to de-tune my bike a little and cure the constant oil seepage at the front of the head.

[Linked Image]002

[Linked Image]001

[Linked Image]004

[Linked Image]003

It was successful and I've been a happy Norton owner ever since.

I'm moving now and I'm faced with what to do with this head. In case you're not aware, the stage one hop up for these bikes involved milling .100 off the head to raise compression. Several people rode this bike include Peter Eagan of Cycle world and they've all said it had more power than their own bikes.

So, the head. I discovered that two of the head bolt holes need thread repair and that is why it leaked oil. The bike ran fine before I took this head off, but it has a fair amount of miles on it. I did a solvent test in the ports and none of the valves leaked solvent.

What's it worth? With a thick head gasket and the thread repair, this could be a good head again. The exhaust port threads look sound.

If no one wants it, it will go to the dump. If someone does, drop me a PM. I'll post this on the garage sale in a couple of days otherwise.

Cheers,
Bill

Last edited by HawaiianTiger; 07/14/18 12:35 am.

Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Support Your #1 BritBike Forum!

Check out British motorcycles for sale:
British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America
Check out British motorcycles for sale:
British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America
Re: 850 RH10 Stage one head [Re: HawaiianTiger] #741815
07/14/18 1:53 am
07/14/18 1:53 am
Joined: Aug 2001
Posts: 2,332
Oztralia
R
Rohan Offline
BritBike Forum member
Rohan  Offline
BritBike Forum member
R

Joined: Aug 2001
Posts: 2,332
Oztralia
'Thread repair' to where precisely ?

Has this head already had 100 thou milled off it, it doesn't look like it in the pic ?
Thats a lot more than the 40 thou the factory took off a Combat head.

'Dumping it' sounds a little bizarre, as it looks to be mostly in quite good condition.
A new Fullauto head is $2000 ++
But I've already got something very similar on the shelf..
(And, they make lovely ingots of metal, if they are really past their use-by date)

Re: 850 RH10 Stage one head [Re: HawaiianTiger] #741819
07/14/18 2:23 am
07/14/18 2:23 am
Joined: Mar 2006
Posts: 1,370
Magnolia, TX
htown Offline
BritBike Forum member
htown  Offline
BritBike Forum member

Joined: Mar 2006
Posts: 1,370
Magnolia, TX
They make spacer plates to go under the barrels, Drops the compression.


1978 Bonneville T140E
1974 Trident
1970 BSA Thunderbolt
1971 Norton Commando
1972 Norton Commando
1973 Norton Commando
1974 Norton Commando
2004 XL 1200R Sportster

Everything will be alright in the end. If its not alright, its not the end.
Re: 850 RH10 Stage one head [Re: HawaiianTiger] #741826
07/14/18 3:31 am
07/14/18 3:31 am
Joined: Jun 2007
Posts: 6,082
Maui Hawaii
HawaiianTiger Online content OP
BritBike Forum member
HawaiianTiger  Online Content OP
BritBike Forum member

Joined: Jun 2007
Posts: 6,082
Maui Hawaii
There are two bolt holes at the front of the head that are threaded. Studs are fitted there, not bolts.

The head is as I got it installed on the motor. Bill Getty built this motor way back when there was a classic bike racing called "Battle of the Twins" and this bike was built specifically for that.

So, no, I didn't do it, and I can't actually measure how much was taken off. I'm going on my memory of what Bill told me about this particular head.

It really would be a shame to dump it. It fits neatly in a large flat rate priority mail box. So shipping is about 20$.

If you had a runner, you could probably clean it up, and drop it on and it would run OK.

I don't do things that way, but some do. I would take it all apart and replace whatever was needed.

The thread repair isn't that big of a deal. I could do it in my garage. It's the higher compression that you need to deal with.

Cheers,
Bill



Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 850 RH10 Stage one head [Re: HawaiianTiger] #741829
07/14/18 4:27 am
07/14/18 4:27 am
Joined: Aug 2014
Posts: 1,022
.
Les P Offline

BritBike Forum member
Les P  Offline

BritBike Forum member

Joined: Aug 2014
Posts: 1,022
.
You better add another $1000 to your FA estimate Rohan.

The three 3/8 stud threads pulling out of the head is nothing unusual as the pitch in the head is not course enough.
When Jim Comstock did my 750 head he inserted those threads (and the exhaust port threads) in ali / bronze, that material in 20 TPI is fine and you would be hard pressed to pull the insert itself out of the head (courser thread) , the stud would snap first.

Some people use 20 TPI steel inserts and some go to 18 TPI and a modified stud (as posted by Mr Comstock)

The RH10 is a very good head, perhaps the best unit, with no broken fins or other calamities like hogged out inlet ports it is worth good money.

Last edited by Les P; 07/14/18 5:03 am.

More bikes and projects than you can shake a stick at but they should be done in two shakes of a lamb's tail.
Re: 850 RH10 Stage one head [Re: HawaiianTiger] #741831
07/14/18 5:13 am
07/14/18 5:13 am
Joined: Jun 2007
Posts: 6,082
Maui Hawaii
HawaiianTiger Online content OP
BritBike Forum member
HawaiianTiger  Online Content OP
BritBike Forum member

Joined: Jun 2007
Posts: 6,082
Maui Hawaii
I think I'll post this to eBay with a .99 cent starting price.

That's worked pretty well for me lately.

I'll give it a couple of days before I do that just to give members here first crack at it.

Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 850 RH10 Stage one head [Re: HawaiianTiger] #741833
07/14/18 6:26 am
07/14/18 6:26 am
Joined: Nov 2009
Posts: 2,222
Netherlands
Peter R Offline

BritBike Forum member
Peter R  Offline

BritBike Forum member

Joined: Nov 2009
Posts: 2,222
Netherlands
Originally Posted by HawaiianTiger
This is a head off my '74 850. I replaced it with a standard head about 8 years ago due to the fact I wanted to de-tune my bike a little and cure the constant oil seepage at the front of the head.


Bill , are you sure that the seepage at the front of the head is not caused by a small crack between the pushrod tunnels and the 5/16 stud hoes ? This is unfortunately fairly common on 850 heads, and hard to detect with the naked eye. I would not buy a used 850 head that is not pressure tested.

Last edited by Peter R; 07/14/18 6:59 am.

Peter.
1974 Commando 850
1972 Trident T150T
1961 Goldie DBD34
1969 Benelli 250 sport special
Re: 850 RH10 Stage one head [Re: Peter R] #741845
07/14/18 2:01 pm
07/14/18 2:01 pm
Joined: Nov 2006
Posts: 443
Wisconsin, USA
F
franko Offline

BritBike Forum member
franko  Offline

BritBike Forum member
F

Joined: Nov 2006
Posts: 443
Wisconsin, USA
Good Morning Bill: You over your P.M. limit

Re: 850 RH10 Stage one head [Re: HawaiianTiger] #741846
07/14/18 2:37 pm
07/14/18 2:37 pm
Joined: Dec 2004
Posts: 9,593
Scotland
kommando Online content
BritBike Forum member
kommando  Online Content
BritBike Forum member

Joined: Dec 2004
Posts: 9,593
Scotland
In the UK there is laser welding being applied to these heads to fix this leak, my RH10 is starting to show signs too, so if a retorque does not fix it then it's off to be fixed this winter.

Re: 850 RH10 Stage one head [Re: kommando] #741862
07/14/18 5:22 pm
07/14/18 5:22 pm
Joined: Nov 2009
Posts: 2,222
Netherlands
Peter R Offline

BritBike Forum member
Peter R  Offline

BritBike Forum member

Joined: Nov 2009
Posts: 2,222
Netherlands
Originally Posted by kommando
In the UK there is laser welding being applied to these heads to fix this leak, my RH10 is starting to show signs too, so if a retorque does not fix it then it's off to be fixed this winter.


Some time ago I asked a question on this forum about laser welding, but got no replies. I am curious how this will turn out, Laser welding offers possibilities for repair, on parts that that were previously due for scrap.

I had a small crack in the head of my 850, and repaired it by de-greasing with brake cleaner, and applying Loctite 290, this type of loctite has capilary properties, put some in the pushrod tunnel, and made a pressure test rig, wth some overpressure, I reckoned that the Loctite would penetrate extra deep in the crack. The repair is holding out so far, (I keep my fingers crossed )


Peter.
1974 Commando 850
1972 Trident T150T
1961 Goldie DBD34
1969 Benelli 250 sport special
Re: 850 RH10 Stage one head [Re: HawaiianTiger] #741866
07/14/18 6:36 pm
07/14/18 6:36 pm
Joined: Jun 2007
Posts: 6,082
Maui Hawaii
HawaiianTiger Online content OP
BritBike Forum member
HawaiianTiger  Online Content OP
BritBike Forum member

Joined: Jun 2007
Posts: 6,082
Maui Hawaii
Mailbox cleared out.

Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 850 RH10 Stage one head [Re: HawaiianTiger] #741868
07/14/18 6:41 pm
07/14/18 6:41 pm
Joined: Jun 2007
Posts: 6,082
Maui Hawaii
HawaiianTiger Online content OP
BritBike Forum member
HawaiianTiger  Online Content OP
BritBike Forum member

Joined: Jun 2007
Posts: 6,082
Maui Hawaii
Well, I suppose it could be. I had a lengthy discussion about with Bill Getty some years ago and he was proposing the vacuum resin injection as a cure for the porous heads.

I'm not sure. I removed and replaced the head twice. The leak would return but only after some period of time. That made me suspect it was something besides the porous casting.

And, every time I went to remove the head, those two nuts under the head were loose. Turns out, the threads were pulling out. They're not completely stripped out now, but they are so weak that they won't hold torque and need to be replaced.

Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 850 RH10 Stage one head [Re: HawaiianTiger] #741870
07/14/18 6:59 pm
07/14/18 6:59 pm
Joined: Dec 2004
Posts: 9,593
Scotland
kommando Online content
BritBike Forum member
kommando  Online Content
BritBike Forum member

Joined: Dec 2004
Posts: 9,593
Scotland
Norman White is getting the heads laser welding so start with him. This may be who he is using

http://www.e-m-p.biz/laser-welding/classic-cars/

Re: 850 RH10 Stage one head [Re: HawaiianTiger] #741900
07/14/18 11:29 pm
07/14/18 11:29 pm
Joined: Jun 2007
Posts: 6,082
Maui Hawaii
HawaiianTiger Online content OP
BritBike Forum member
HawaiianTiger  Online Content OP
BritBike Forum member

Joined: Jun 2007
Posts: 6,082
Maui Hawaii
I'm getting a bit more conversant with these heads thanks to AccessNorton site.
So, the ports have not been hogged out from what I can tell. I measured with my calipers 1.17 across the port which is a little less than 30mm.
I take it that the 32mm ports don't necessarily give any advantage with power, ie, bigger isn't always better.

I did run 32mm carbs with this head though and it made great power. Nothing at all to complain about. Great torque and a huge boost once on the cam. Really fun power band.

With the stock head on there now, the power at the top end has been reduced somewhat. Probably a good thing to slow my old ass down a bit anyway.

Don't know which cam but suspect it's a stocker. The bike was built for endurance, not necessarily just speed.

Which certainly has worked. Almost 60K miles on the motor with only two top end jobs and no bottom end rebuild yet.

I found only two RH10 heads for sale globally. One for 400$ and another for 1000$ both with more serious issues that my head has. Both were incomplete as well while mine has all parts still attached.

I think I've made a good choice not to junk this one.

Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 850 RH10 Stage one head [Re: HawaiianTiger] #741911
07/15/18 1:59 am
07/15/18 1:59 am
Joined: Mar 2006
Posts: 1,370
Magnolia, TX
htown Offline
BritBike Forum member
htown  Offline
BritBike Forum member

Joined: Mar 2006
Posts: 1,370
Magnolia, TX
32mm carbs are stock with that head. The intake manifolds that go with it have a taper from 32 to 30.


1978 Bonneville T140E
1974 Trident
1970 BSA Thunderbolt
1971 Norton Commando
1972 Norton Commando
1973 Norton Commando
1974 Norton Commando
2004 XL 1200R Sportster

Everything will be alright in the end. If its not alright, its not the end.
Re: 850 RH10 Stage one head [Re: HawaiianTiger] #742039
07/15/18 11:45 pm
07/15/18 11:45 pm
Joined: May 2007
Posts: 10,650
Pennsyltuckey
ricochetrider Online content

Moto Mojo
ricochetrider  Online Content

Moto Mojo

Joined: May 2007
Posts: 10,650
Pennsyltuckey
Bill
I was looking at RH10 heads a while back. New ones are astronomical in price so unless it is really bad (yours isnt), it could be worth at least a few hundred dollars. Like 500 or more. A guy offered to sell me a used head in very good to excellent condition for 900, which I thought was damn nice of him. Least expensive new one I saw was about 2700.00 if I recall correctly

Last edited by ricochetrider; 07/15/18 11:46 pm.

"It is no measure of health, to be well adjusted to a profoundly sick society."

Re: 850 RH10 Stage one head [Re: HawaiianTiger] #742675
07/21/18 12:10 pm
07/21/18 12:10 pm
Joined: Aug 2001
Posts: 1,286
Hamilton, Mass. USA
D
Dave Comeau Offline

Crew Chief
Dave Comeau  Offline

Crew Chief
D

Joined: Aug 2001
Posts: 1,286
Hamilton, Mass. USA
To determine the heads residual deck height ...measure the depth of the squish band.
.125" is typical as stock.
IMO any cut 850 head is the result of builders being to cheap to have proper high compression pistons sourced or made.
FWIW full auto heads NLA


dynodave
BSA 3 1961-1963
Ducati 3 1992-2002
Norton many 1951-1975
87 Serv-Equip 100HP MC brake dynamometer,
Re: 850 RH10 Stage one head [Re: HawaiianTiger] #742793
07/22/18 9:27 pm
07/22/18 9:27 pm
Joined: Jun 2007
Posts: 6,082
Maui Hawaii
HawaiianTiger Online content OP
BritBike Forum member
HawaiianTiger  Online Content OP
BritBike Forum member

Joined: Jun 2007
Posts: 6,082
Maui Hawaii
Thanks for the tip.
I heard that the combat heads are milled for higher compression like the stage one hop up recommends. True?
Also, that RH10 heads can be used on 750's with a little modification. True?
Would there be any advantage to using the RH10 on a 750?

The reason I'm asking is that there is someone near me with a Combat Commando. And he's also gone bonkers on Nortons since he first rode mine.
And wants to sell off his Triumphs and BSA to buy more Nortons.

You know, I did warn him that would happen....

He might want this head....

Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 850 RH10 Stage one head [Re: HawaiianTiger] #742816
07/23/18 1:22 am
07/23/18 1:22 am
Joined: Mar 2006
Posts: 1,370
Magnolia, TX
htown Offline
BritBike Forum member
htown  Offline
BritBike Forum member

Joined: Mar 2006
Posts: 1,370
Magnolia, TX
Bolt patterns are different between the 850 and 750. They can be made to work but involves welding and remachining. I've looked for both 750 and 850 used heads and 750's are relatively easy to find, 850's not so much. The other 850 head is the rh4. A lot of people prefer the rh10 as the rh4 can crack around the valve guides.


1978 Bonneville T140E
1974 Trident
1970 BSA Thunderbolt
1971 Norton Commando
1972 Norton Commando
1973 Norton Commando
1974 Norton Commando
2004 XL 1200R Sportster

Everything will be alright in the end. If its not alright, its not the end.
Re: 850 RH10 Stage one head [Re: HawaiianTiger] #743013
07/24/18 7:26 pm
07/24/18 7:26 pm
Joined: Jun 2007
Posts: 6,082
Maui Hawaii
HawaiianTiger Online content OP
BritBike Forum member
HawaiianTiger  Online Content OP
BritBike Forum member

Joined: Jun 2007
Posts: 6,082
Maui Hawaii
Head is sold.
Thanks,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.

Moderated by  Dave Comeau 


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
Powered by UBB.threads™ PHP Forum Software 7.6.2