The first question to answer perhaps is   Why would you want to ?  after all, arent all Gold Stars supposed to be uncompromising, a bit of an animal and, if you want a tourer then surely a Gold Star is not the right machine.  Whilst the purists would have you believe that the Clubmans specification is the only true Goldie, a racer on the road, thats far from how the manufacturer saw the breed. A quick glance through the catalogue shows that you could specify almost anything from a mild tourer to the full blown racer, along with everything in between and a lot of people had them all their guises.  In my humble opinion, there are very few motorcycles ( if any ) that wore so many different hats so successfully.  So,        

Objective

Having owned, ridden and most importantly enjoyed a Gold Star for more years than is probably good for me and, with no desire to stop doing more of the same it quickly became apparent on moving to the Island in June 2004 that, if this one was going to be used to any great extent then one or two modifications to its Clubmans spec would make life more relaxed and allow the bike to be just a bit more user friendly. If these changes could be accomplished without them becoming irreversible, dramatically altering its appearance or costing a fortune, then that could be considered a real achievement.

Changes

An assessment of what could be changed was the first step. A few of the modifications were obvious, whilst others required a little more thought. The obvious included parts like the clip-on handlebars and the gearbox and these were promptly replaced with items already in the spares cupboard, ( note: there is no difference between top gear in the close-ratio and standard gearboxes, only how big the steps are to get  there ). The overall gearing was also lowered slightly by a change of engine sprocket from 19 down to 17 teeth. Less obvious were some of the bits in the engine. The cams and, more importantly the crankshaft pinion that drove them were changed for standard items and, this necessitated a change of valve clearances and to the ignition timing of course. However, despite these changes, it was considered the one thing that would really transform matters was the instrument that controlled carburetion.

Which

Where to start was the first hurdle. There are more models of carburetor available than you can shake a very big stick at and making a sensible and practical decision on which would best suit this engine meant asking a lot of questions and talking to everyone who might have an opinion. Needless to say, finding opinions wasnt hard, finding practical suggestions well, that was another story.  In the end, as is usually

the way, the best solution turned out to be the most awkward to achieve, a MK2 Concentric.

Method

Those who know what a MK2 Concentric looks like will also know that attaching it to a flanged cylinder head usually requires the use of an adaptor. These adaptors and the short rubber tube that is supplied with them for normal fitment of one of these carburetors add considerably to the length of the inlet tract and in this application, would prevent the use of a velocity tube. The solution was to machine a flange that would match the 2 stud flanged cylinder head, but have a central bore that would fit over the outer diameter of the inlet side of the carburetor, the only problem then, how to attach this flange to the carburetor.  With welding considered impractical, the only alternative way forward was some sort of adhesive that could be injected into the very small gap between the inner bore of the new flange and the outer diameter of the carburetor inlet stub, this adhesive would need to remain flexible when cured, be heat resistant and impervious to fuel and oil. A few years ago perhaps this specification would have been a tall order, but luckily times have moved on and a quantity of the appropriate adhesive was obtained. To further ensure the security of this flange it was drilled and tapped top and bottom and grub screws were fitted, these being secured with the same adhesive. The end result is an assembly that is both secure, crucially air-tight and which hopefully, does not look particularly out of place. To date, it has certainly turned a few heads!

Performance

After concerns about the amount of downdraft a MK2 Concentric would cope with were alleviated by an informative chat with Hitchcocks Motorcycles ( their advice was 15 degrees from horizontal and, despite appearances, this application is not very close to that ) the time arrived to try a start. This proved completely uneventful with the engine responding well to adjustment of the idle and mixture screws and quickly settling to a steady tick over.  A ride up the road proved the response on small throttle openings was a vast improvement over the previous instrument, but, after a check on the plug showed that the mixture was a touch on the lean side the needle was moved up one slot, this one adjustment has resulted in a much healthier plug colour, smoother acceleration and improved torque over the whole of the useable range. Fuel consumption, whilst not a driving factor for this modification, appears to be also considerably improved, the ease of starting and the lack of a black smoke screen when the throttle is whacked open are all further advantages that should not be dismissed lightly.

Conclusion

Here we are in late June and having now put a couple of hundred, trouble free miles under its belt the question has to be, has it been worth the trouble ?  The answer to that must be a resounding Yes, even though I can hear everyone saying well you would say that wouldnt you.  I can only say, youre welcome to try it down the road and form your own opinion, other than that, Im afraid you will have to take my word for it. Im going to continue enjoying my motorcycling on a calmed Gold Star that is a lot more practical than its original incarnation and most importantly, its now even fun to ride and what’s even better, one days work would see it back in its original incarnation, a real result. 

Regards

John Oborn