This bike was in production from early 1978 to sometime in the 1990's It was available in 3 versions.
1) Disc brake wire wheeled sports version
2) Later sports version with alloy wheels
3) Later commuter version with drum brakes and wire wheels.
Eariest bikes were 12bhp and 8500rpm, 50mm bore 50mm stroke, disc valve 2 stroke. Maximum speed in low 70s and 0-60 somewhere around 14 to 16 seconds.
Later bikes were detuned to 11bhp
They weighed just under 200 pounds and had 6 volt electrics.
Good seating position and seat, however pillion foot rests on swinging arm.
Horrible, 6 volt lights and points hidden behind a flywheel which were difficult to adjust.
Ease of maintenance
Pretty good 1/2 hour to swap a piston, brake pads easy to change. However points difficult to adjust as removal of flywheel is necessary.
Good and bad, electrics were a problem but rest was quite good, needed a rebore after 10,000 miles - of being thrashed. Points were a bane all the time I had the bike, I hate points they are horrible and a maintenance nightmare - directly caused two holed pistons due to timing being out.
It along with lots of bikes of that period tended to rust easilier than it should. - I had to rebuild the fork legs with epoxy resin in the pits and gaters fitted.
Quite good 60-80mpg, cheap tyres, plugs needed regular changing, 2 stroke oil easy to put in every few 100 miles (I think a filling lasted about 500 miles), pistons were cheap at £6.50
Not bad, on par for the class, main problem was bouncy suspension.
Best in class by a long way, first 100 with hydraulic front disc brake. Capable of outbraking most vehicles on the road.
Standard: Very good for the class - OK best - it was the fastest 100cc production bike all the time it was on sale, cruises on ordinary roads at the limit without being flat out, could break 70mph on the flat but was tiring to ride at that speed as you had to conserve your speed.
Modified: Due to watching a race between Barry Sheen and Kenny Roberts I crashed on a tight right hand bend and cracked the exhaust, 3 months later I replaced it witha Micron exhaust, a bit noisy but greatly improved performance. I up geared (15 to 16 tooth front socket), rejetted (97.5 to 102.5 main jet), replugged (grade 8 to grade 9 NGK spark plug, porting played with.
Genuine 80mph on the flat (still accelerating), 11-12 seconds 0-60, faster than any standard 125 including the Honda twin. This was 80mph at 9500rpm including up gearing - it would pull to 10,000rpm
great cheap first bike, easyish to maintain, fun to ride, easy to tune. It could be ridden as a go to work/school bike, or thrashed for fun without too much licence risk.
Good points : Performance, brakes (if disc), cheap to run.
Bad points : Electrics, fragile to rust.
What would have made it a better bike?
12v electrics, electronic ignition, better rear shocks, front fork leg gaters, some anti rust treatment on exposed areas