1Sometimes /lve believed as many as six impossible things before breakfast said Alice in Wonderland. Perhaps one of them was the Stray Panther ŁŁŁ
It all happened because I took the magneto off a Panther engine and saw the "shelf" below it and thought it could be just the place for a second cylinder . I discussed it with members of the Panther Owners' Club. It turned out a few people had thought about that, but couldn't work it out, partly because there was nowhere to put the second camshaft asthe oil pump would be in the way. It was one of those impossible jobs , so I thought I'd try it .. .'
Geoff Stray's Panther M240 V twin has been five years in the making and hasappeared at the Bristol Classicshow for the last three years in various stages of development. First it was an engine, then a mock up with exhausts and finally a nearly finished machine. In summer 2020 the whole plot hit the road.
At one end there 'sthe front forks from a Honda Fireblade with a Cb750front spindle, the steering stem for a Norton Commando, clip ons from a Suzuki and off the shelf rearsets;at the other end there's a rear wheel with the conical hub from a Triumph Bonneville.
And then there's the bit in the middle , which is a 64 degree hand made 1300cc V twin with its origins in Cleckheaton . Geoff, a confirmed Panther aficionado , used a pair of M120 barrels.the M100 items he'd originally considered wouldn't double up, because of their U bolt barrel fixings.
He got hold of two sets of M120 crankcases,cut the front part off one set with an angle grinder, filed it back till it all fitted then took the two parts to engineers Hamlins .They jigged it all up and it was taken to an alloy welder who stuck it together . Hamlins then re machined it. Easy when you know how, eh?
Geoff used blade and fork conrods from a Buell Xb9,as one big end runs inside the forks of the other, allowing the use of a single crankpin and keeping the cylinders in line. These were just 1mm longer than the Panther rods and had enough meat on the small end to allow some machining. Geoff used modified Rover car pistons, a common M 120 upgrade. The crankpin needed to be machined and the flywheels skimmed to make it all fit together in the casings.
The removal of the magneto drive meant that there was no drive to the oil pump. So after a lot of head scratching and trying
things for size,geoff realised that the oil pump from a BSAA10 could be made to work if it was mounted on the outside of the timing cover,with the oil running through a detachable external Norton I Citroen oil filter and lots of delectable copper tubes . Oh, and there's a modified adjustable oil pressure relief valve, too.
The cam drives also required a lot of imaginative thought. Fitting two of the original pinions wouldn 't work asthey would be too wide, but Geoff heard of a French builder who had created av twin from two BSACL Osand he'd reduced the width of the pinions by half. Geoff did the same, but was concerned that the narrower pinions would suffer when trying to operate the Panther's heavy duty valve gear, so he went back to Dresda, who came up with some lightweight valves and springs.
He was originally going to use a Norton Commando primary drive and chaincase, until he realised that the planned Burman gearbox wouldn't line up with the rear sprocket. So,the box and clutch from an early Ariel Square Four were pressed into service. The alternator is a tiny Kubota, designed for a lawnmower but also used on light aircraft. Driven by a 1:1 belt, it's not quite powerful enough to provide juice for the lights, charge the battery and fire the Yamahavirago electronic ignition system.
'It might be wired up wrong. There's more wires on it than there are in the manual:
Geoff doesn't have an engineering background: 'If I start doing anything and it turns out too complicated, I go and ask people. We work it out, discuss it and modify the ideas until it works:
The frame isafeatherbed. Except,it isn't. Originally, the plan was to put the engine into an Egli type frame.'i tried to make it fit, but it turned out the Egli frame was about seven inches too short. I did find a builder in Switzerland who said he could do it, but I'd have to take the engine to him, so that was out:
Instead he took the engine to Yeomans,to see if it would fit in a featherbed frame they had in stock. It did, with a lot of wiggling about, but Geoff decided that the clearances were a bit too tight. He then went to Dresda, and they brazed together a featherbed replica that was three inches longer and an inch and half taller than the original. Yeomans supplied the Norton Dominator tank , which was modified to fit.
The silencers, which are silent only in their name, replaced four Matchless megaphones, after it proved difficult to get those to mate with the exhaust pipes and not fall off. The rev counter has the innards of a kitchen clock, which given the low revving nature of the M240, seemed appropriate. A pair of compression plates reduce the ratio to 6.2:1.'It would be nigh impossible to start without them:
On the advice of Panther racer Wil I Hawkes, there is a cable decompressor on the rear cylinder, and the front cylinder uses Panther's half lift decompressor the tiny lever on the timing case designed to aid starting . Starting the Stray Panther M240 really isn't challenging, honestly.
'It's simple. You just turn on the petrol, tickle the carbs, turn on the ignition, find top dead centre, engage the decompressors, push it pasttdc, let go of the rear decompressor and give the Honda kickstart a boot. Once it's started you must remember to turn the half lift lever off or it doesn't run at all well:
The lump of firewood you can see in the pictures isn't part of the creation. Panthers don't come with a sidestand , but the owners' club sells one for the singles which bolts onto the bottom of the crankcase. Geoff modified one of these to use at140 Bonneville stand, but kicking over a 1300V twin which was resting on it proved too much for the bracket and sheared off the bolts shortly before the picture was taken. The stand is now getting welded to the frame instead. And the tank will be getting a new and very swish look.
Last summer was all about trying out trying the Panther out properly.
'I've been scraping my feet cornering on Dartmoor; said Geoff. 'I'm going to need new boots. The brakes are superb, and the engine pulls very nicely. It's one of the best handling bikes I've ever ridden, better than my old Rickman Bonneville, or my Evans:
The Evans,by the way, is another hand built V twin in Geoff's stable. That's got a motor made out of two BSA850 cylinders with a 9.5:1compression ratio and no decompressors, mounted in a slimline featherbed frame.
'I'm an ideas person, really; says Geoff .'I like working on things that people say are impossible and then try to prove they can work .. .' Re