I am just starting to restor my 61 cb72 which has lain in the back of my garage for 35 years.
I used to race it as a 350 way back and relieved the head to clear the pisons. Does any body know if the "skull" is steel or cast iron, as I would like to resore it to original size. I have searched in vain for a 61 head, also barrrels.
Any info gratefully received.
Cylinder head "skull"Hi Kenny,
Welcome to the Forum. I'm pretty sure the combustion chamber inserts are cast, machined steel. I'd be concerned about heat affecting the aluminum head and the insert's fit in the head if you're going to try building it up with welding rod. Of no particular relevance... your "Chipping Sodbury" has taken over first place in my list of member's great location names from 48lesco's "Olmsted Twp".
Thanks for the info. The head would be O.K. as is for "show". but I would like the bike to "go".
Chipping sodbury is a small market town on the edge of the Cotswold Hills near to Brisol. It's claim to fame is that it once had so many pubs that it was not possible to have a drink in all of them before passing out!.
61 CB72 headHello Kenny
I dont think you would need a actual 61 head, so long as it is of a CB72 (250 unmodified)any year will work. I think the main diffrence with the early head is only the 10mm plug size. I probably have a CB72 head (later type) if you get stuck but they are so heavy that the carrige gets expensive and you probably can find one localy. From experience Hotshoe is right, it's bad enough getting some of them to "seal" even standard. Also may have 61 cyl. 250 and 350 but do you have o.s. pistons already ? Gordon SAFOJ Hi Kenny
I might have something to swap with you. I have a couple of heads for my 1963 CL72. Not sure when the parts changed but I would be interested in your re-profiled head as I am planning to build a 350 motor myself. Let me know and I'll have a rummage through my parts. Regards G '60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F
Hi Gordon
Thamks for the reply, I have a later head and will probaly have to use that. No on will know unless they pull the spark plug caps, but my ultimate goal is to restor it to original. If you have a 61 (end oil feed) barrel I would be happy to give you a good price for it. G-Man If you are buildig a 350 engine them the CB77 head already has the machining done. I built mine originaly using the Read Titan kit, but the pistons were very poor and had a nasty habit of self destructing at any thing over 10500 rpm. I think (it was 40 years ago)_that I ended up using CB350 pistons with some minor machiming of the squish band. I am hoping that if I can find enough parts to rebuild the racer as well. When I think of all the genuine race kit bits that went in the scrap all those years ago I almost cry!
61 barrelHello Kenny
I have a 61 barrel CB72 250 and one with 64mm 350 liners, unfortunately I think the 250 one is .25 OS and has some damage so would require boring, I think it would need to go to 1mm OS ( or if you want to "cheat" CB250K ) pistons to clear. The 64mm one is based on a 250 (247cc) barrel and was probably a Read Titan or similar item. Its worn but useable if you are going 350 or could be re.linered I expect. Do you have "250" pistons already ? I have some STD new ones but they are no use for the OS. 61 cyl. Possibly someone else on the site can help ? Gordon SAFOJ
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