Hi, I am new to this forum, and I hope you can help. I brought a Norton 650 race bike back in 1977 and did a bit of racing, until I got married and children arrived. When I brought the bike I didnât really ask many questions about its heritage. I have kept the bike and am in the process of restoring it. However, after reading about the Dunstall racers I am now wondering if I have an original 650 Dunstall Dommiracer. Some details
Unfortunately the engine has no numbers.
The bottom end - has a lightened and polished crank assy. Con rods are Alum alloy, bottom caps steel and polished, Cams runs on needle rollers & is drilled through centre for oil, oil fed to cam on crank case. Cam followers look standard, but are lightened. Push rods all Alum alloy.
The Top end - rockers lightened and polished, head has been worked on big valves and polishing, high Comp pistons. Breather attached to inlet rocker cover.
The frame - number all I can see is M 122 7342. It seems to have been modified to a Manx race style frame. Also the swing arm has had a stiffening brace added. It has a Manx mag alloy 4 speed close ratio gear box, race magneto, front wheels are Manx but it has a modified as the brake plate seems to have been cut down to minimum with a thin alum alloy disc attached to what was left to provide the venting.
I have some photos from when I stripped it down but are too big to attach. Can anyone shed light on the bikes heritage?
The frame is from a Domina…
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Previously Neil Wyatt wrot…
Previously Neil Wyatt wrote:
The frame is from a Dominator 88 (500cc) around 1957 without looking at the book. 650's were all slimline from the factory. Your frame will be a wideline. All I can tell you for now.
Hi Neil,
Thanks for the response. I have attached a picture of the frame components. The swing arm has been braced and I assume this is not standard. Also it looks like the primary oil feed from the frame has been added. It seems to be that the frame been modified to a Manx style for racing at some stage of its life. Could this be a Dunstall modified frame?
Attachments frame-1-jpg- Log in to post comments
Previously david_green2 wr…
Previously david_green2 wrote:
Previously Neil Wyatt wrote:
The frame is from a Dominator 88 (500cc) around 1957 without looking at the book. 650's were all slimline from the factory. Your frame will be a wideline. All I can tell you for now.
Hi Neil,
Thanks for the response. I have attached a picture of the frame components. The swing arm has been braced and I assume this is not standard. Also it looks like the primary oil feed from the frame has been added. It seems to be that the frame been modified to a Manx style for racing at some stage of its life. Could this be a Dunstall modified frame?
Hello Now Paul Dunstalldid use featherbedwide-line frames, but I Do not believe this is one of them Someone has done some work on this frame to copy Dunstall and a 650 motor with no stamped number is suspicious its one that droppedfrom under the microscope as it were, take the engine to Steve Maney to have a look at it to see if it OK to race again your anna j
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The frame is not a Manx. T…
The frame is not a Manx. The frame number is a give-away. The first letter is the year code, followed by the model code. 12 indicated 500 Dominator, the following 2 means featherbed. Road frames have a vertical tab on the cross tube behind the steering head, Manx had a horizontal tab. The loop behind the seat rails and brackets for racing numbers on the rear subframe are racer mods in imitation of Manx spec.
I can't see if it has the sheet metal gusset under the steering head as used on road frames. It was fitted because early road frames suffered fractured down- tubes, largely from going up kerbs. This would not happen if the road frames had a decent head steady like the Manx. The road twin ones are not much good - but the ones fitted to featherbed Internationals is much worse....
FWIW I know a race twin in a Wideline frame which has a tube running from the top of the steering head to the cross tube at the back of the petrol tank, and no cylinder head tie. Sweet handling and much reduced engine vibration. This additional tube is removeable and sits inside a tube through the petrol tank
Paul
Previously david_green2 wrote:
Previously Neil Wyatt wrote:
The frame is from a Dominator 88 (500cc) around 1957 without looking at the book. 650's were all slimline from the factory. Your frame will be a wideline. All I can tell you for now.
Hi Neil,
Thanks for the response. I have attached a picture of the frame components. The swing arm has been braced and I assume this is not standard. Also it looks like the primary oil feed from the frame has been added. It seems to be that the frame been modified to a Manx style for racing at some stage of its life. Could this be a Dunstall modified frame?
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Previously paul_standeven…
Previously paul_standeven wrote:
The frame is not a Manx.
Paul
David said the gearbox was Manx, not the frame.
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Many thanks for all your c…
Many thanks for all your comments. re "sheet metal gusset" yes there is one. So it looks like someone took a wide-line featherbed frame and did some mods to make it more suitable for racing. Re Engine - There is evidence on the casings of where the engine plate with a number should have been, so it was not just stamped on the casings. I have attached some pictures of the engine internals. I think I will probably end up making it into a cafe racer and made be parade it rather than race it.
Attachments engine1-jpg- Log in to post comments
The frame is from a Dominator 88 (500cc) around 1957 without looking at the book. 650's were all slimline from the factory. Your frame will be a wideline. All I can tell you for now.