GO-FASTER MODS, SILENCERS AND AIRBOXES
As previously mentioned the black cap annular discharge silencers do not significantly reduce power, but
they must be kept with the balanced exhaust pipes. If you want to fit earlier separate pipes then you must
fit the earlier reverse cone silencers. The reverse cones can be fitted onto the balanced pipes but with a
slight loss in power What did restrict performance was the black plastic air box, remove this for a 750 type
one to gain performance.
Mother lower performance factory modification was the restriction in the inlet valve throat often down to
29mm, re open to 32mm all through.
750 single pipes can be made to tuck in better.
WHEELS AND BRAKES
WHEELS: Rust from front disc tends to fly off on to the chrome rim and stick there, Clean it off before it
imbeds itself. Single rot',' wheel hearing retainer is said in manual to have a left-hand thread--not always
true, Rear wheel bearings tend to disintegrate, suggestion is for an improved roller hearing, as the original
are not scaled type. Rear axle material appears inadequate in most cases. (I broke one once at 80--quite
fun TRS ) Some rear bearings are the sealed type.
REAR DISC CALIPER: Needs yearly dismantling and cleaning out, (not a bad idea for all hydraulics).
Disc pads, especially rear, could benefit by a dab of silicone grease on their rear (non friction surface).
The front brake can be improved by refitting in the back of fork leg as in Mk 1 and MK (I. Master cylinder
on handle bar, if there is fluid leak due to the poor seals, do replace them as it has been known for fluid to
get the wrong side of piston and LOCK front brake on! (I cannot see how this could possibly happen even
though I worked for Lockheed for four years TRS). On dismantling the rear master cylinder and
unscrewing the two body halves which have a right-hand thread, there is a locking alien grub screw below
the surface of the body, lost in the muck to be removed first. Some rear wheel retainers have a right-hand
thread. This hag worked loose a few times, allowing the cush drive back plate to rattle The Last time it
started rattling I tried to tighten it up but found it was already tight. The problem seems to be that the steel
bearing retainer has worn into the alloy cush drive centre. This is because the retainer is screwed up solid
but the cush drive centre moves in its rubbers.
On re-assembly of master cylinder take care, as you screw the two halves together. a fraction too far and
the push-rod begins to operate the master cylinder, whose first move is to block up the return hole for
brake fluid, when in use heat expand-, brake fluid which cannot return to reservoir, therefore pressure
builds up in the system, which applies the brake! It can be very embarrasing stuck in the middle of the
road with a locked back brake, I know!
TWIN LEADING SHOE FRONT BRAKE: The effectiveness of this brake can further be increased by the
manufacture of a longer operating arm. i e. the one with the cable connection. )f this is done without the
brake stiffening kit. the flexing of the brake cams in !he hushes hinders any advantage, so add 1} inches
to the brake operating lever after fitting the brake stiffening kit.
FRAME PARTS AND HANDLING
HANDLING: An improvement is to fit the Norvil head steady, it will (7t under the Interstate tank, but a hit
of juggling is needed to fit it under the Roadster tank. Norvil head steadys are rare and complex though. 'I
he Norvil head-steady whilst improving handling will. when shimmed up correctly. cause mom vibration to
he transmitted through the frame. A "half-measure" s to reduce the shimming of the unit, but the Mark III
head-steady is adequate for normal road use.
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Summary of Contents for 850 Mk 1 1974
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