Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/125790
By John Hu~tter
The,re are some racen, mainly those
who first got hooked on dirt 'tracks in ,.
,the 1950'S, who will never be happy
riding anything but a thumper. There
are still dozens of racers, now several
wrinkles older, who dream wistfully
about their Velocette, Matchless, or
Gold Star. There was never anything
else like the reassuring thumping of a
500 single. They were forgiving...well, at
least you could tell a split second before they spit you off so you could lay it
down and ride it out...and they were,
without a doubt, real motorcycles.
The only problem is that the big,
heavy British marques are no longer
competitive in anything like stock form
on scrambles and oval tracks. This is
particularly true in the Sportsman class.
If you wan t to go fast and have
competitive
handling,
it's a big
two-stroke or a super trick Triumph,
and the latter usually make it on raw
horsepower rather than handling or
finesse.
Cheer ~p, there is an answer. It's a
fairly good answer, though not a simple
one, find an engine you like, a big
thumper with potential that isn't too
fussy and build your concept of the
ideal machine around it. Some people
will laugh at the idea with all the hot
two-strokes available; four-stroke freaks
read on. It can be done.
Steve Keull is a Sportsman IT rider,
who does some occasional Hat-tracking,
if it's being offered as part of the
program. He is also a dedicated
\ four-stroke rider. When the new BSA
500 MX came out, he was down at the
dealer's, money in hand, like a lot of
other riders who remember the good ai'
days. But the BSA MX was designed for
motocross, mainly to be ridden by John
Banks. People have been winning on
them in scrambles, bu t it still wasn't
quite right.
Steve looked around and started
talking to the people at Red Line. They
had
a 4130
chrome-moly
steel
nickle-plated frame that was designed to
fit the 441 ,or 500 BSA engine. He
picked up the large size Ceriani forks,
plastic fender and Bates seat, some
Webco E-4 bars, Akront rims and (What
else?) Pirellis to shoe the bike in his
mind, then started assembling The
Complete Sportsman Scrambler.
The BSA engine came out of the
stock frame and was torn down to be
cleaned up. Nothing radical was done as
there seemed to be enough poop from
the stock mill. The valves were polished
on a home grinder and all moving parts
were clearanced to the correct specs.
The only damage in the BSA engine
after a year and a half of running was to
the rocker arm bearings, plus the
exhaust
valve
seat
was
pitted.
Everything else was in good shape.
One interesting thing came to light.
The 500 MX comes equipped with a
32mm Amal carb, but the inlet port is
only 30mm, same as the B50T engine.
The difference was blended out the
length of the port to smooth the intake
flow. Five hundred MX owners, take
note. You could possibly even bore it
0llt to the full 32m diameter.
rn
THUMPER:I~AL"E
All engine work and tuning was done
by Rich Lizardo, another old-time
scrambles freak. It was all a home
workshop project, with the addition of
some few expensive but important
components like the Red Line frame.
The BSA engine slipped into the Red
Line better than it fit in the stock
frame, with about two spacers for the
front mounting bolt. Heavy duty PVC
oil lines went on in place of the stock
items. Stock chain and carb went back
on. The rear sprocket was dropped four
teeth. Steve had been running with a
megaphone pipe and had the brackets
rewelded to fit the new frame.
A lot of money went into it, mainly
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Number plates went on before the pipe and
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The converted Red Une BSA looks light enough to be a 250. Very spacey
___;-~ (]
presents
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1.6 Mile True European Course, Jumps, Water
TROPHIES
To Finishers
SILENCERS!!
Classes 100 - 125 - 250 - Open
POWDER PUFF
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