1971 "Signal Orange Roadster" with 750cc Shortstroke Engine
After Tim Seifert built his blue 750 Commando the lure of a bog-standard Commando Roadster made me buy a 1971 Commando last registered about 20 years ago, partly dismantled and never restored, from an old customer. The plan was to restore it to original condition, but the best-laid plans of mice and men....
While still going through the assortment of parts that were disguised as a 1971 Interstate, and in many cases weren't, the first thing was to look the bike up in the production records.
According to these the bike started life as a signal orange Roadster!
The next hickup was the chance meeting of a customer in Hungerford who told me he had an original 750 short stroke engine for sale. Never having seen, let alone ridden one, I had to buy it.
Needless to say after some TLC from our engine man Rudi Kolano the short-stroke engine is now in the Roadster.
Doing away with the heavy steel shortstroke conrods and replacing them with standard Commando ones meant the cylinder barrel had to be shortened.
Also, doing away with the shortstroke pistons meant replacing the RH7 head without squish band with a 750 head with squish, so the engine rebuild became slightly more complicated than usual.
The bike was completed days before the start of the 2011 "Old Boy's Tour", a 3-day journey in the Alps on various Nortons we do every year,. The bike behaved well with few minor teething troubles in those three days.
What became apparent is that the bike does not like to pull from low revs, so in comparison to Tim Seifert's 750, which is geared identically, one needs to change down a gear to pass an obstacle with the same acceleration he has available. The fact the carbs were opened up to 33.5mm whilst, to keep the looks original, they are in the usual position when a longer inlet tract was beneficial, does not help.
Bike has our stiffening kit in the front brake , a Pazon ignition , our Production Racer type headsteady , and a PW3 cam .
The sound is beautiful, and as soon as the revcounter goes beyond 3.500rpm the bike starts to fly.
While still going through the assortment of parts that were disguised as a 1971 Interstate, and in many cases weren't, the first thing was to look the bike up in the production records.
According to these the bike started life as a signal orange Roadster!
The next hickup was the chance meeting of a customer in Hungerford who told me he had an original 750 short stroke engine for sale. Never having seen, let alone ridden one, I had to buy it.
Needless to say after some TLC from our engine man Rudi Kolano the short-stroke engine is now in the Roadster.
Doing away with the heavy steel shortstroke conrods and replacing them with standard Commando ones meant the cylinder barrel had to be shortened.
Also, doing away with the shortstroke pistons meant replacing the RH7 head without squish band with a 750 head with squish, so the engine rebuild became slightly more complicated than usual.
The bike was completed days before the start of the 2011 "Old Boy's Tour", a 3-day journey in the Alps on various Nortons we do every year,. The bike behaved well with few minor teething troubles in those three days.
What became apparent is that the bike does not like to pull from low revs, so in comparison to Tim Seifert's 750, which is geared identically, one needs to change down a gear to pass an obstacle with the same acceleration he has available. The fact the carbs were opened up to 33.5mm whilst, to keep the looks original, they are in the usual position when a longer inlet tract was beneficial, does not help.
Bike has our stiffening kit in the front brake , a Pazon ignition , our Production Racer type headsteady , and a PW3 cam .
The sound is beautiful, and as soon as the revcounter goes beyond 3.500rpm the bike starts to fly.
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