Honda
CR750
Honda returned
to the track for the 1970 Daytona meeting with
a machine, which to conform to the prevailing
rules, was based on their newly introduced CB750
Four. Success at Daytona offered huge benefits
for the company in terms of promoting the CB750
and consequently Honda signed up Dick Mann,
Ralph Bryans and Tommy Robb to spearhead the
assault. During the race Mann rode conservatively,
preserving his machine whilst his major competitors
retired with various problems, resulting in
Mann taking the victory.
In recent years the ready availability of CB750Æs
and the existence of a number of different race
series for which CR750 replicas are eligible
has prompted a number of companies into producing
items that enable the conversion of the CB into
a CR replica. This well known example was built
during 1999/2000 and raced over the subsequent
six seasons by the present chairman of the CRMC,
Roger Bryant.
The standard frame was modified to a similar
pattern as that employed by the original CR750,
incorporating extra bracing and fabricated footrest
hangers mounting works pattern cast alloy footrests
and a cast alloy rear brake lever. The CR750
type alloy fuel tank is equipped with a flip
up fuel cap (with a titanium lever) and Honda
fuel tap and is complimented by an alloy oil
tank with an anti froth system, a race seat
and a copy of the CR750 fairing. The four pipe
exhaust replicates the original CR750 system
but incorporates internal baffling resulting
in a 105db noise output and has recently been
repainted and repacked. The front forks utilise
revised springs, sourced from the States and
have had their damping modified and mount twin
callipers, one of which has been modified resulting
in both bleed nipples pointing to the front.
Cast iron, drilled disks compliment the callipers
and braided lines are used. The rear drum has
been lightened and both wheels employ alloy
rims that have recently been fitted with new
Dunlop KR racing tyres.
The engine was built with the same attention
to detail as the rest of the machine, featuring
modified crankcases with the excess alloy removed,
a steel cam chain tensioner wheel and a stronger
go-kart sourced chain replacing the original
cam chain. The K0 series head is equipped with
Black Diamond racing valves and springs and
a Kenny Harman D grind camshaft. Wiesco two
ring pistons are connected to alloy race spec
rods sourced from Japan.
A Quaife close ratio five speed gearbox and
race clutch springs ensure that the power is
transmitted effectively to the back wheel. A
digital Boyer Bransden ignition system equipped
with mini digital coils provides the spark whilst
race jetted CB750 carburettors fitted with alloy
bell mouths meter the fuel mixture.
During 2007 the machine benefited from new
paintwork in the Honda race livery of red with
a silver fairing and the seat was recovered.
A new final drive chain, clutch lever, clutch
cable, plugs, oil filter, clip-ons, grips and
a AP Racing brake master cylinder and lever
(with variable ratio). All the fluids have been
replaced as have the feed and return oil pipes
and the callipers have been overhauled and refinished.
Featured in the July/August issue of Classic
Racer.
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