SOME TUNING TIPS FROM C. BRADDICK
"DOUBLES" CAMSHAFT: This was definitely the most troublesome cam produced but probably the most
powerful on sale to tile Public. The problem associated with it were: -
1. Overlap-this was so large that with the lightest over-revving (missed gear usually the.cause)
the Valves touched each other and bent. Singular remedy is to reduce the overall diameter of the
make heads.
2. Coil bound spring, ie. due to cam lift-using standard springs, collars, cups and insulating
washers and springs do get coil bound. On NO ACCOUNT remove the heat insulating washers
as heat anneals springs. Coil-bound springs break very quickly and this can go undetected for a
tong time save for a misfire at 4,500 plus. The proper way to overcome this problem is to re-
machine the collett recess in tile valve further up the stem by about 1/16th of an inch (1.5mm),
this has another advantage, it reduced the spring preload of the valve on the valve seat. This
gives tile whole valve train a much easier life and makes things run much easier. A high preload
is totally unnecessary. The only way to get the BEST results from a "double S" cam is to have the
head re-machined full sphere with re-angled inlet valves (as originally dune by Paul Dunstall and
now by Mick Hemmings). The valves still need re-machining though. HIGH-SPEED WEAVING:
Worn rear tyres also have the effect of producing high speed weaving. Do not ask why, but it was
consistent in racing that the rear tyre had to be kept with plenty of tread on it otherwise the hike
shook its head. Worn rear tyre affects handling at all speeds and fitting u new one restores
handling instantly. Fit 3.60x19 on front, riot 4.10x19.
REAR SUSPENSION UNITS: If you have gut a good-handling hike and never carry a passenger then use
100 lb springs on the hardest setting, absolutely essential! Girling gas shocks definitely improve handling
and are worth considering which replacement is due.
FOOTNOTES
OIL-TANK: On my production raring Commando the handling was so good that on left-hand corners I
could )can the bike so far that the oil ran out of the oil tank breather tube, down tile rubber tube and onto
the hack tyre--alleviated by changing the oil tank breathing system.
(Cannot understand this-centrifugal force affects oil ;,s well as bikes so solo cornering has no effect on
level. Perhaps your new system "as just better? T.R.S.)
If the oil tank is over filled it will pump out oil through the air filter.
CLUTCH: Check for buckled driving plates causes "fir. (Solid steel ones) and that, when using solid
Ferodo driven plates, the thick pressure plate is used. If the thin one from the 850 bronze clutch is used--
clutch slip. Instead of a 750 type pressure plate you can try doubling up one of the plain or friction plates,
depending on how worn )our clutch is and therefore how much extra room there is.
ROCKERS: Take the springs out and replace with phosphor bronze or steel spacers and by adjusting the
spacer and shims get the rocker end dead central on the valve. This is a tedious process but essential for
efficient running, i e. for racer and wang artist.
CRANKCASES: When bolting crankcases together it is essential that there are no 'tight' spots when the
crank is rotated. I have seen this and it is caused by: (a) bearing mis-alignment-a piece of aluminium or
grit trapped behind the bearing outer race is all that is required to throw it off line; (h) mis-aligned crank
cases caused by burrs, grit etc on the mating faces. Essential to check this on new cases.
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