Faults:

Charging problem, caused by corroded rectifier lead.

A seized front caliper. It's a cable operated affair, rather than hydraulic.

A sliding-type caliper too, which is absolutely fine and those opposing piston types fitted to every sport bike are a bit of a con. As long as the caliper is designed properly, there simply is no advantage of having the extra piston(s) as Subaru & BMW on their Impreza & M3s prove.

Piston & rings failure at 6,000 miles, down to my then lack of knowledge and the abuse I subjected the Suzuki to.

General Comments:

Early in 1980, my mum & dad surprised me when - out of the blue - they agreed I could have a moped when I was sixteen in April that year. 'But you are not getting bigger & bigger bikes'... Yeah.

I paid for it myself from my wage as an apprentice Datsun car mechanic: £29/week, £18/month for the bike.

A visit to the local bike shop and I'd made my mind up within 30 seconds. A two-stroke Suzuki GT50, red tank & black side panels, 900 miles from new with a useful top box. I took the '5-Star' training course at a local school playground (failed) on a Saturday morning and by midday, I rode off on the 30mph motorcycle.

Actually, the law allowed the design speed to be 'up to 35mph' which mine just about did. In other countries, the GT50 had 6bhp and around 50mph. My restricted version, 5-speed transmission, would flatline at 6,000rpm. The 49cc engine was so quiet, nearly silent, I thought I'd stalled it at the first junction!

Riding around for hours every evening and weekend, I absolutely loved this bike. By the end of the first week, I'd started to decode those restrictions Suzuki had put in place.

There were so many: a very thick head gasket was first to go, lapping head to cylinder, this brought a noticeable improvement on pick-up. The larger engine sprocket did not.

Biggest change was from removing the chocking airbox silencer which meant 43mph. The new sprocket worked okay now too. The exhaust wasn't restricted, so I looked at other bikes with the same Suzuki engine. Port timing was obviously very restricted in comparison to the Dutch market TS50. Copying those figures, a bigger A100 20mm carb, opening the reed stops and then going a bit further than the TS50 porting, saw me with a bike which was now a noisy bike, was much faster than stock and would rev to over 10,000rpm. However, it still was still only about as quick as a Suzuki AP50 which had an engine dating from the mid-sixties or the equivalent Yamaha FS1-E...

One of the bike's qualities was the trials bike like performance of the engine. Stock it would pull away in fifth gear, really, with hardly any transmission snatch. You could use it off road and it would climb any hill, such was the bike's flexibility.

An ill conceived experiment with model aircraft glow plug fuel saw the piston & rings fail. A rebore and 'Hepolite' piston cured that mistake. After a year's ownership I saw an advert for a 'Malossi' 75cc performance kit. It came with a 'racing' cylinder, bigger piston and Italian 20mm Del'Orto carb, which leaked fuel from various places, necessitating turning the tap off 100yds before coming to a stop to drain the float chamber.

Their expansion chamber exhaust was no different in comparison to stock, but was retained as the original one was now battered. I did some mild porting to this cylinder and skimmed the head to give a .75mm 'squish band' clearance. The bike new flew. Best top speed was a timed 71mph on the M65 which was under construction at the time.

Fuel consumption was a bearable 60mpg and reliability was good.

Throughout the bike's life, it had an unusual tendency to abruptly stop from spark plug 'whiskering' which is mentioned in older text books on two-strokes, but seldom experienced. The bike would suddenly lose power, then preignition followed by breaking down. Remove plug, break the 'whisker' and carry on. I later discovered that removing the plug cap and replacing it forcibly would - 9/10 times - be suffice to break the whisker. Apparently the whisker is made from fine metallic particles from the plug's centre-electrode and bridges the gap, shorting it between the two electrodes. A change of oil from Mobil to Castrol finally cured it.

If I'd have done some more research, I would have known that the RM50 & RM80 motocross engines are much the same at the GT50 and would have bought a RM80 motor with around 18bhp; it would have been the ultimate, easily beating GP125s & KH125s. Even the later water-cooled RM80 will fit the 50cc frame, as will the Suzuki GP125, requiring only basic metalworking skills. The GP100 actually looks quite stock in one of these bikes with the lighter weight making 75mph possible. An RM80 should top 80mph with ease?

Lots of fun, I learned a lot about bikes from the little GT50. With hindsight, I'd have bought the excellent Suzuki ER50 which looked great with big bike looks.

There was a mint GT50 with tons of NOS parts for sale at £2,000 five tears ago. Nowadays a good one is easily close to £4,000. Simply too much, when there are endless bigger classic Japanese bikes around, like the ace Suzuki A100, which I now own. Better in nearly every way too.