When I stripped the Mk3, amongst the many ‘modifications’ I found, was a belt drive combined with conversion to RH gear change. The inner primary case had been modified, presumably to enable the gearbox to pivot for belt tensioning - see attached photos. Given the work that would require red to recreate the seal housing, the case is scrap as far as I am concerned, as is the gearbox cradle, which was similarly butchered in the same expert way. Replacement NOS items have been found fortunately. Replacements for all three gearbox castings had to be sourced too (the main casing was cracked).
Why mess with a Mk3 like that when the earlier models are so much more easily converted without the irreversible damage, if a belt drive is so desirable? I personally would not have one, as I prefer the standard arrangement, including the starter, and have seen the consequence of belt shedding.
Andy
Most bikes
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Guilty as charged.I ran a…
Guilty as charged.
I ran a Mk3 engine in a race bike. Running the hydraulic primary chain tensioner was a disaster so I slotted the engine plates, opened up the hole in the back of the primary and glued a seal in with silicon. Other shaft holes and ES flange were blanked off. Then cut the back out behind the clutch when I went to belt drive. Gearbox was RH shift with pre-Mk3 covers. Chaincase outer was cut to improve ground clearance.
In the 80s Commandos were two a penny and breakers were full of crashed spares.
More recently I welded in new metal and re-drilled the engine plates - looks entirely original. Fortunately I had spare chaincases and had kept the original gearbox covers, LH lever mechanism, chain tensioner and starter gubbins.
edit:
If I read this right, you bought a Mk3 with RH gearshift and an adjuster on the gearbox top bolt in plain sight. What did you expect to find?
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Of whatever brand go through phases of life from new pride and joys, to nice used bike, to old nail or hack before the split off into breaking for parts/scrap or possibly recognised as a future classic.
Add in that there would also be times during its life where spare parts were not available (e.g. primary chains?) and you can perhaps understand why 'modifications' like on yours were done. Could it have been done better or differently? Certainly. Did that meet the price limit or skills of the then owner at that time? Sorry, but the jury is out on that one.
To me, it is fixing or improving things like this that is one of the joys/frustrations of looking after our old bikes.
'Criminal'? No, just part of its history.
Just my thoughts.
George.