screws which have 4BA spanner size but the right 2BA threads (B.S.A. number 40.0683 ==Triumph E7680) being
smaller you might remember not to heave so hard. Finally the points cover has a little hole which is to let oil/water
out and therefore goes at the bottom. Boyer or RITA electronic ignition cures all!
OIL PUMP: The oil pump takes a long time to wear out, but when the mains go it's a good idea to recondition it, as
all those bits of bearing have to go through the oil pump on their way to the tank-full instructions are given for this
operation in the workshop manual. Usually, you'll be glad to know, no new parts are required. If you have changed
the cover, the gasket, or the oil pump, check that the little conical black rubber on the pump is just compressed-it
shouldn't be possible to push the cover quite home by hand. If the cover is very proud, check that there aren't too
many shims on the oil pump under the black rubber. They tend to stick together and not get noticed. For the hat few
years these shims haven't been used, a paper washer between the oil pump and the crankcase is used instead. I have
heard of engines which ran quite successfully for a while without the rubber seal-because somebody forgot it (no it
wasn't me)-the theory is that the centrifugal whirling of the crankshaft forces oil out into the big ends and draws oil
into the crank. The output from the pump is enough to drench the hole so that air isn't drawn in. No oil goes to the
rocker gear, though, as this requires pressure.
Mention of pressure brings me to another point-the fitting of oil pressure gauges. On the Commando (and for similar
reasons. most bikes) an oil pressure gauge is more of a liability than an asset. It is of necessity, fitted on the feed side
where any failure of pipe or gauge is disastrous to engine and rider--it's touch and go whether the engine seizes
before or after you fall off with oil on the back wheel. On the Commando this failure could be caused by engine
vibration in the same way that early rocker pipes failed. (We're coming to that.) The other reason that a pressure
gauge isn't much good is really twofold. At high speeds and high oil temperatures the pressure can drop to nothing
on the gauge because the pump can hardly keep up with the rate the stuff is flying out of the big ends. The
centrifugal force can keep the pressure at the big ends above the danger point, so there's no real panic--but the gauge
would inspire you with horror. Then of course if you did seize an oil pump by the time you noticed that the pressure
had dropped the big ends would have gone (. . . through the hole in the crankcase, with average N.O.C. luck!). If you
want an interesting gauge to frighten yourself with, but, which is inherently safer and can give useful information, fit
an oil temperature gauge in the oil tank. Let me know what it reads as you change into top for the Mountain Mile on
both the fourth or fifth lap! The latest Racing Nortons (we can't call them J.P. Nortons any more as they've stopped
the bikes from smoking) had a new type of oil pump-I wonder if this is because the ordinary pump can't keep up?
ROCKER FEED PIPES: Rocker feed pipes are fitted with 3 identical banjo bolts (5/16W spanner size) and copper
washers, which won't leak if properly annealed. Do this by heating on a gas flame and allowing to cool. Quenching
gives no real advantage, except speed, unless you quench in very dilute battery acid as this saves having to scrub the
scale off. (Don't use this acid in a battery afterwards though). The banjo bolt has holes in the sides and up the
middle, so avoid plastic gasket here because if Loctite gets in the threads the bolt may break when you next try to
remove it. Position the rocker pipe so that it cannot rub on the head steady, the frame or the gearbox cradle. 850
rocker pipes have reinforcement to avoid chaffing. It would he useful to keep an eye on these rubbing points, as the
rocker pipe runs at big end pressure and the slightest hole can rapidly lose you all your oil, your big ends, your
crankcases.... This makes it particularly important to know that the early all metal rocker feed pipes failed regularly,
and I would certainly recommend anyone
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