The re­turn of the GP and Goldie mythol­ogy

Rick lets style take prece­dent over prac­ti­cal­ity – but ar­gues it’s also go­ing to make him hap­pier

Classic Bike (UK) - - News - IL­LUS­TRA­TION: IAIN@1000WORDS.FI


Now hear me out... I know I said it was fool­ish to try and do two things, and it made sense to set up my newly-in­vig­o­rated Gold Star on the eas­ily-tuned MKI Con­cen­tric carb and think about re­vert­ing to the GP later but I’ve weak­ened and the GP is back on.

I’ll be hon­est, it just looks bet­ter and if that means a bit of hard­ship, well, that’s style for you. No pain, no gain – and be­sides, if I’m go­ing to have to spend ages set­ting up the carb, I’d pre­fer that it’s the one I want on there, not a com­pro­mise.

The Amal GP is a track carb, only fit­ted to Goldies for rac­ing ho­molo­ga­tion pur­poses – well, that and be­cause it was the only Amal made that could ac­com­mo­date the mas­sive 1½in in­let port at the time. The big Con­cen­tric came later and of­fered im­proved start­ing and a tick­over with only a mod­est loss of top speed. Or at least, so they say; but Goldies are re­spon­si­ble for more myth and leg­end than the cat­a­combs of Tran­syl­va­nia and I don’t fully be­lieve it. If any­thing, a race carb should be more tune­able than a road bike – and rac­ing bikes that don’t start are use­less. Any­way, since get­ting the power back after sort­ing the squish, I ob­served two things with the Con­cen­tric fit­ted pre­vi­ously. First, it was an easy starter. I al­ways as­sumed dif­fi­cult Goldie start­ing was ei­ther due to wet­ting the plug or the low-speed un­friendly valve over­lap, but the float height is a bit low on the Con­cen­tric and it won’t start un­less you flood it very lib­er­ally, so maybe it needs more (not less) fuel to start. Se­condly it no longer seems to smoke. Be­fore, you’d get the odd waft at traf­fic lights. Since the car­bu­ra­tion was al­ways a bit rich on the GP, I did won­der if this was ‘bore wash’ – ex­cess fuel di­lut­ing the oil. I read an in­ter­est­ing book­let by 1920s carb man­u­fac­turer and ex­pert Charles Binks in the VMCC li­brary re­cently. Binks said that, within rea­son, a low float height was no prob­lem but high was dis­as­trous. Sup­pos­ing my GP height – although set cor­rectly – was still too high, wet­ting the plug on start­ing and over-richen­ing the mix­ture enough to wash the bore at low speeds... more clues, more ex­per­i­ment to do…

Does a Goldie need a GP Amal to look right? Dis­cuss…

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