GROUPS 19, 21-24, and 28:- Handlebars, side panels, front mudguard, seats, rear mudguard, tank and
instruments
All straight forward, no comments.
GROUP 20:- Exhaust systems
Not much to say about exhaust systems-I have already had a go about port threads. Don't use mutes in
the straight through silencer ends, if they are brazed in file them out again even if it takes all weekend.
They will put fiat spots in the carburetion and make the whole plot nasty to ride. From a silencer point of
view the long-cone-and-short-reverse-cone type of silencer is just the same as the shortish-cone -and -
long ish-reverse -cone type, but the cylindrical type with a black end is much quieter and DOES NOT
REDUCE THE POWER. Officially, you need different pipes for each type of silencer, but with a bit of
initiative it's surprising what can be done.
I won't say anything about side covers and their fittings because they are, to use an expression used only
under extreme provocation by our President, rather pisspotical.
Mudguards and tanks all straightforward.
GROUPS 25, 26, and 27:- Electrics
As string does not conduct electricity, change the H.T. leads for proper ones made of real metal. Chop
the ends of the metal battery strap off to stop it from poking a hole in the capacitor. If you are tired of
messing about with points and auto advances, fit a RITA ignition kit-from John Carpenter, Mistral
Engineering, 63A Turner Road, London E17, an excellent bit of kit.
The harness has got three spare wires in it so that Interplods can flatten their batteries more quickly than
us ordinary mortals, and on ordinary machines they are not connected at either end. They go from the
headlamp to just behind the head steady, and are colored purple and green, brown and black, and brown
and purple. If you need a spare bit of wire at the roadside you can use these-but it means unwinding the
harness tape to get at them.
Be careful that the negative battery terminal MUST NOT touch earth anywhere, because this will short out
without going through the fuse, and will melt the earth wires (the red ones) throughout the whole wiring
harness. Makes a mess and a smell. You can get Halogen bulbs part no. 457 to fit in the old style
headlamp lens, but it's a bit antisocial as the cut of on dip isn't good enough. Better to go all the way and
get the complete unit-Lucas part 54526114, or any 7in Quartz unit from a reputable maker. Wipac Quad
Optic, an excellent chap unit. Cibie Z beam is another good choice.
GROUP 29:- The tool kit
There is one useful modification that you ought to make, to the Allen key. It won't St the screws which are
most likely to come undone-the ones holding the manifolds to the head. You must shorten the short end
to just before the bend, and if you can, bend the ,long bit away slightly in the middle-so the result is a
slightly S-shaped Allen key. Then not only will the short end go into the heads of the screws, but the long
end will miss the nut holding the -inlet rocker cover on.
If you find yourself with a spare weekend and a grindstone, here are one or two other useful
modifications. Round off all the corners of the tappet adjusting spanner, so that it won't mark the edges of
the hole. Grind metal off the sides and outer edges of the 9/16 A.F. spanner so it will fit into the clip
holding the chainguard. Finally thin down the points of the 1/2in A.F. so that it will only take you an hour to
adjust your primary chain.
32
Summary of Contents for 850 Mk 1 1974
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