Halfway point? - resto update

I'm an innocent soul, so yes. I can make an educated guess, and I don't
want it confirmed....

 

said...

I spied a B50 being MOTd in central London last week. What a fucking
racket it made.

--
Lozzo
GSX-R1000 K1, GPZ500S, GSF600W
BOTAFOT#57/70a, BOTAFOF#57, MIB#22, TCP#7,
ANORAK#9, DIAABTCOD#14, UKRMT5BB, IBW#013, MIRTTH#15a/16,
BotToS#8, GP#2, SBS#10, SH#3, DFV#14, BONY#9, OMF#18.

 

The 380cc motor revs higher than the longer stroke ones, so its better
for faster tracks in drier conditions. They used the 605cc in the wet,
as it had a lot more torque and was easier to ride than the smaller
motors in the wet. The 605 is a motor than was subsequently put into
production by CCM.

k

 

What like his information pertaining to a cobbled up RC125 with a Hiro
engine being a Fantic production bike..................dont make me
laugh!

k

 

Lets hope you can do it better than you can spell it Dave
m8.......................could be pretty messy if you cant!

k

 

You seem to talk it most of the time, so surely this practice must be
familiar to you?

k

 

Not me guv - MX has never really interested me. To answer 441cc
Thumper, choosing different bikes for different conditions is normally
due to the power delivery rather than how high they rev. You'd
typically choose a bike with less of a hit for tight events such as
woods enduros, as they're less tiring when you're constantly on/off the
throttle. Similarly for events where low-speed traction is important,
which may include getting out of the slow corners on a very wet MX
track.

So it's not that high-revving suits a dry track, but more that smooth
low-end with less of a hit suits a wet track, iyswim.

--
Krusty.

http://www.muddystuff.co.uk
http://www.muddystuff.us
Off-road classifieds

'02 MV Senna '96 Tiger '79 Fantic 250

 

By 'hit' you mean rapid onset of the power band? ie, you want torque
that rolls in nice and smooth from low in the rev range?

Ant

 

Showing that you are a total fuckwit again then Andy...............the
BSA factory is hardly going to announce Jeff Smith was on a 605cc bike,
when competing in the world 500cc championship are they?

k

 

I guess you know all about building 441 motors then, and have wide
experience of pre-65 MX, and have actually ridden these bikes in
competition? If not you are making yourself look idiotic..............

k

 

Hehe, are you saying BSA cheated?

 

The sports version of the B31 was the Gold Star. The 441 was an
enlarged version of the B25 which as far as I know had no
relation to the C15 which was a standard commuter bike and did
not have a unit engine. I can not remember if it had anything to
do with the Tiger Cub but it is unlikely as that originated as
the 150cc Terrier and was stretched to 200cc.

High performance 250s date from the change in the law that made
them the biggest bike a learner could ride. The Royal Enfield
Crusader dates from about the same time as the B25 1960 or so.

Ken Young

 

Sure did................lol. BSA were very interested in winning the
world MX championship, and they even tried a titanium chassis on the GP
bikes, but had quite a few problems with breakages, and I dont think
these were used for any length of time. BSA also at one time even
converted a B50 motor for speedway use.............and one of the mods
was to saw off the rear of the crankcases containing the gear box!

k

 

The 441 was in fact an enlarged version of the B40 motor, which was
itself a stretched C15 motor. The first 441 Victors were introduced in
1966, the B25 the year after in 1967. The final version of the 441 was
the B50 of 499cc.The original C15 was a beefed up design based on the
Cub, which was poached by BSA when they took over Triumph.

k

 

Ant

 

Definitely agree with this, Andy, except that it's Alan Clews!

Unless you can prove that you worked in the BSA comp shop in the 60s, I
don't believe a word of this, Ken! Those engines were stripped down by
the FIM after every race and any oversized engine would have been found
out straight away. I think you'll also find that Smithy's world
championship winning bikes were 420cc, not 380cc. And I'll thank you
not to suggest one of my boyhood heroes was a cheat!

They did, however, build a titanium framed bike and there was an
article about it in MotorCycle Sport & Leisure recently. In fact, I
think it was a reprint of a Frank Melling MCM article from the 70s with
Jeff Smith's own version of the truth. Not only the frame but some of
the internals such as the con-rod! I think work-hardening in use caused
serious troubles but I'm not a metallurgist so don't understand these
things!

Finally, Ken, I think you'll find that the 608cc capacity (88mmx100mm)
was a CCM 'invention' not BSA's.

Oh, and *all* the unit beezas are descended from the Terrier of
1953(?). Yes, the cylinder became vertical from the C15 onwards, plain
bearings were replaced by balls & rollers etc. etc. but you can't deny
their ancestry. Even CCM's final 620cc 'crossers.

I agree with everyone that 441cc Thumper's bike is looking superb!

Mark

 

Coo, there's a surprise

I don't read MCSL, but I remember that Motorcycle Mechanics, as then
was, did a fascinating article on this beast, about 25 years ago. They
reckoned that it cost a quarter of a million quid, in 1970s values, once
you factored in the time taken to make it.

 

A bike restorer I know was provided with full spec of the 380cc motor,
by the person who had Jeff Smiths ex works motors to
rebuild...................



k

 

The 605cc bike wasnt any quicker you prick.............it was slower
than the smaller cc bike, but had a lot more torque, which made it
easier to ride in the wet! Have any of you ever ridden a BSA scrambles
bike I wonder?

k

 

bike I wonder?
Not an ex-works one, no but I have ridden a 580cc CCM, have you?

And I still don't believe that BSA used a 608cc engine in the 60s,
sorry!

Mark