PIP HIGHAM Pip on communication
What’s the most important thing in this place: a curt question from my third engineer when I was a pup in the Merchant Navy a few years back. “Erm... is it, erm... spanners?... or air?... dunno boss, gizza clue.” “Comm-yew-nick-hey-shun! I speak, you listen.” True dat, no question, but as with so many things in life, conveying a message to a mate is frequently easier said than done. I used to have a well trotted few lines about fuel delivery and the necessity to flow half a gallon a minute for safe operation of a well sorted GS/GSX. Less than that and top-end performance (is there any other kind?) would be lost, possibly accompanied by a toasted piston and fricasseed valves for pudding. The inevitable response was that when they pulled the fuel pipe off, petrol pissed out, much akin to the store’s hoss. “But how much does it flow?” “Erm, loads.” Not good enough. A quick demo and a few calculations would reveal the feebleness of the donkey concerned, the net result: occasionally they’d get the message and take steps to resolve it (big fuel tap, no filters, enhanced tank breather etc) but usually they’d go away muttering about the state of my mental health. No worries on that count though, eh? There were similar confabs about the first start-up after a rebuild, the cost of which might have run from a monkey (that’s £500) up to a couple of grand. Start adding up straight-cut primaries, a Wiseco piston kit, some Vance & Hines cams plus work, ignition bits and you get the picture. In several cases the hapless miss, missus, girlfriend etc was frequently unaware of the cost of this kitchen/bathroom refurb alternative expenditure. Billy the bike would run into the workshop with a brown envelope containing, let’s say seven-and-a-half, (while girl female parked the van) thrust it into my hand, and with a finger to the lips, his I hasten to add, the unspoken truth was set. As Billy’s companion walked in, he’d be busy counting out £250. “Oh that’s reasonable, I thought it was goin’ to be a lot more than that.” These words were generally spoken with the tongue barely contained in the GF’S cheek. Did the subterfuge ever work? I doubt it – there would be a brief conversation, probably followed by a promise to “sort that bloody kitchen out!” in rapid succession. I invariably stressed the importance of a good battery with substantial leads, mineral oil for the first 50 miles and to make abso-bloody-lutely sure that the right lead is connected to the right plug! A start-up backfire can ping a GS starter clutch into oblivion without any notice at all and I’ve even seen a
Z1000J twist the crank when the unfortunate owner got his wires crossed, and not in a good way either. So let’s assume (assumption: the mother of all good cock-ups) that wires are correctly fitted and that volts are plentiful, what could possibly go wrong? Hopefully not much. I usually suggest fresh fuel, and preferably Esso Super Unleaded, still theoretically without ethanol and so it should be at the best part of 30 bob a litre! With luck the freshly tweaked motor will fire up and settle down to a brisk idle, and now is the time to check that oil is percolating to all the right places, which is easy on a GSX – just pull each of the oil gallery plugs out in turn to confirm oil at all four corners of the top end. In reality the lubrication system on any roller crank motor is based on a bit of flawed practice. How so? Well the cam bearings are plain (straight in the head material on Suzukis but running in shell bearings on Kawasakis) and generally rely on a high (60psi or thereabouts) pressure supply. Unfortunately, our favourite muscle bikes, Zeds and GS/GSX have roller cranks that prefer low pressure but high volume supply. This is an unhappy compromise, exacerbated by the fact that the cams are elevated above the crank and as the law of gravity still appears to apply even at grassroots level, it’s a stretch to coax oil up to the aforesaid plain bearings in the cylinder head. And you might ask what pressure the oil pump can supply? After all, if you remove the lower oil gallery plug on a GS the oil, much like the previously mentioned fuel, ‘pisses out’, so it must have lots of pressure mustn’t it? Nope, a warm GS/GSX at idle might not make above three or four psi! The cams live on a wing and a prayer. The whole subject of flow rates and pressure related oil and fuel delivery is complex, but intriguing, I’ll be back.