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Valve guide replacement #694110
05/06/17 12:46 am
05/06/17 12:46 am
Joined: May 2017
Posts: 3
Ohio
G
Gmchief Offline OP
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Gmchief  Offline OP
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Joined: May 2017
Posts: 3
Ohio
I have a 71 commando 20m3 motor. Need to replace leaking valve guide. Should i use bronze guides. Soft or hard? Thanks for your time. Ralph

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Re: Valve guide replacement [Re: Gmchief] #694140
05/06/17 9:46 am
05/06/17 9:46 am
Joined: Aug 2014
Posts: 859
Australia.
L
Les P Offline

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Les P  Offline

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L
Joined: Aug 2014
Posts: 859
Australia.
If you mean replace all the guides then Kibblewhite C630 guides will have a long life span along with Kibblewhite valves and the cost is reasonable.

http://shop.kpmivalvetrain.com/c/british_norton_750-1968-1973

Those guides need special tools and skills as far as honing.
I picked up a good (cosmetic) head for my own 1971 Fastback off US eBay and had it sent to Jim Comstock who fitted the above along aluminium bronze inserts in the exhaust ports and 3/8" stud threads in the deck.
His rates are very good, quality top shelf.
He then sent the head to me in Australia.

http://www.nortonmachineshop.com/

Re: Valve guide replacement [Re: Gmchief] #694428
05/08/17 4:33 pm
05/08/17 4:33 pm
Joined: Aug 2001
Posts: 68
Central Ohio
P
PFribley Offline
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PFribley  Offline
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Joined: Aug 2001
Posts: 68
Central Ohio
If the guide is leaking around the valve. And guide is still solid in the head. I would find a shop in your area to sleeve it. Much easier than knocking out the old guide. And installing a new one.

Re: Valve guide replacement [Re: Gmchief] #694433
05/08/17 4:52 pm
05/08/17 4:52 pm
Joined: Sep 2007
Posts: 1,090
Ottawa, Canada
gREgg-K Offline

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gREgg-K  Offline

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Posts: 1,090
Ottawa, Canada
I took it from the original post that the guide is leaking at its interface with the head casting ... a fairly common thing in my experience.

Ralph, that being the case, the proper solution is to extract the old guide(s), ream the hole in the head oversize and press in a suitable guide.

If the leakage you've discovered is between the guide and the valve stem, I would check the others too ... unlikely to be only on one.

Agree with Les that Jim Comstock is an excellent resource, and he is located not far from you.

.. Gregg


Spyder Integrated Technologies
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Re: Valve guide replacement [Re: Gmchief] #694436
05/08/17 5:48 pm
05/08/17 5:48 pm
Joined: Aug 2001
Posts: 7,029
scotland
triton thrasher Online content
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triton thrasher  Online Content
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Joined: Aug 2001
Posts: 7,029
scotland
If oil is seeping down the outside of the guide, between guide and head, seal it off with sealant under the valve spring seat.

I must admit I'm assuming Commandos have valve spring seats, reasting on the head.

Last edited by triton thrasher; 05/08/17 5:51 pm.

Amateur Loctite enthusiast.
Re: Valve guide replacement [Re: PFribley] #694488
05/09/17 12:34 am
05/09/17 12:34 am
Joined: Nov 2003
Posts: 699
Orlando fla/ shady valley Tn
B
bill50cal Online content
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bill50cal  Online Content
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B
Joined: Nov 2003
Posts: 699
Orlando fla/ shady valley Tn
very much NOT recommended on the 750 as the guide is to thin it is ok on the 850 as they increased the OD of the guide


Originally Posted by PFribley
If the guide is leaking around the valve. And guide is still solid in the head. I would find a shop in your area to sleeve it. Much easier than knocking out the old guide. And installing a new one.


windy
72 combat
switchbackcreek.com
Re: Valve guide replacement [Re: Gmchief] #694501
05/09/17 1:31 am
05/09/17 1:31 am
Joined: Aug 2005
Posts: 1,225
melbourne florida
B
bodine031 Online content
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bodine031  Online Content
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Joined: Aug 2005
Posts: 1,225
melbourne florida
Can of worms. You just can't pull in a new guide. Guide must be reamed/honed straight. not with a dingle berry hone. Seat needs to be recut because the guide ends up in a different spot. That requires valve to be refaced. how about the valve stem wear. so is the shade tree patch and go or do it correct.
Bill Frease Youngstown 330-360-7921 Rodi's Winder Ga. 770-867-1676 Leo Goff 901-757-1009 & Dave Comeau BB Norton moderator These fellows been at this awhile check with them Your bike your $$$$$$

Re: Valve guide replacement [Re: gREgg-K] #694536
05/09/17 12:48 pm
05/09/17 12:48 pm
Joined: May 2017
Posts: 3
Ohio
G
Gmchief Offline OP
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Gmchief  Offline OP
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G
Joined: May 2017
Posts: 3
Ohio
Got some good answers. Thanks to all you guys.
Seems the best answer is to send it out.


Moderated by  Dave Comeau 


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