Advice wanted on reproduction Manx 5 gallon tanks

Hello Adam. I was looking through old posts and saw your question here. About 20 years ago I bought a Manx style alloy tank which was from Unity Equipe made to fit a Dommie frame. It was flat on the bottom instead of having the curve down at the back that engages the Manx top tubes. The tank was beautiful but it had the fuel taps in the middle-rear as if they were supposed to drop down between a set of splayed carbs as a Triton with a Bonny head, or an early Dominator SS would have with the pre-downdraught manifold. It was pretty useless for use on a bike with a 650ss style head.

I do not know if you have seen any photographs etc. of the works 1962 Daytona 88 racing bike which Heinz Kegler took care of for almost half a century, but it has a wonderful alloy racing tank specially made to work with the slimline frame and Dominator engine. It is also flat on the bottom except for recesses made for the throttle cables and clearance for the head steady etc.. It's most striking feature however is that it is actually a "wideline" frame which utilizes the extra width that most would not think necessary for a slimline frame to locate two petrol taps outside of the top frame rails. This way they neatly drop down beside the carburettors where they can do some good. Three of these bike were built up for the Daytona races in spring of 1962.

It is interesting as a tank because this is the only instance where the Norton racing shop produced a works road-race bike with a slimline frame and special tanks to suit. So it would be the most authentic set of tanks to have on a slimline replica-racer. A few years later Paul Dunstall was tapped to build up four 88ss bikes for Berliner to enter in the races that spring at Daytona Speedway, and if photographs of those bikes are looked at it can be seen that he used modified Manx tanks, as they have the curve downward at the rear like featherbed Manx tanks do. He did use the idea of putting the fuel taps outboard the frame rails though.

Someday I will get the tank off the bike and get some good photos and measurements for those who want a close replica, but for now here is a side-shot of the bike:

By the way, the 62' Daytona racers did not have dents in the tanks for clip-on clearance when new, the dents in this tank were added by Kegler himself by putting a 2x4 board on the tank and hitting it with a hammer.

The extra clearance was needed when some fairings were used which required the clip-on bars to be pulled back further out of the way. Otherwise many Manx bikes did not have clearance dents in the tanks when new as they were not supplied with fairings.

As long as you do not do anything to the bike that is irreversible by some future owner, then you do not have to worry about having it the way you like it.

If you are going to do some spirited riding with those matching number engine and gearbox cases, winding it up to high rpm at full throttle, then you had better make sure it is all in very good condition and at least has good valves, valve springs which are well set up, and some oiling system upgrades. I have done these things to my 62' 650ss which is undergoing some heavy maintenance right now. I have enlarged some of the oilways and will surely run the six-start oil pump gears on it. I also have swapped in some of the later connecting rods with the extra meat on the beam by the big and small ends. I have a lot of old sets of 650 cases laying around here with scars and weld patches in them from connecting rod breaks, this tells me they had some shortcomings. I have put up some of what I am doing to the bike on that Facebook page you are talking about and will put up more as time permits.

Maybe someday if I am lucky I will get the time and money to build up a Dominator street racer from all orphan cases and a frame with no matching numbers, then I can treat it very harshly and not worry so much about it if she blows up or I wreck it.