YAMAHA CS5E

One of Yamaha’s rare sub-250 twins grabs this month’s limelight

A buyer’s guide to this classic Yam tiddler

Sitting pretty as a picture this month is one of Yamaha’s rarer, sub-250cc, two-stroke twins. Sold officially for just one year (1972), the CS5E was probably only a nine-month model here in the UK before it was usurped by the RD200 and promptly forgotten, yet it’s actually the progenitor of the reed-valve twin. Yamaha’s small stroker twins trace their lineage to the Japanese-only market 90cc AT 90 of 1965, which soon became the 100cc YL1. Keen to fill the gaps between 100 and 250ccs, the firm rapidly launched both 125 and 180cc analogues for the 1968 model year. The 180 was sold as the YCS1 or CS1E, the E denoting that the bike ran an electric start. In the American and Canadian markets the bike proved so popular that the importers didn’t even bother with the CS2E that followed. The year 1970 saw the bike grow into a full 200 (actually 195ccs) along with a cosmetic refresh that dropped chrome tank panels, rubber knee pads and the like. The machine (CS3E) proved to be extremely popular and ran into the following model year with little, if any changes, yet in the background Yamaha were on the move after innumerable success on the race track. The success of the reed-valve induction system at GP level had convinced the firm that the same system should be introduced on road bikes. Yamaha planned to fit reed-valves to their entire range for the 1973 model year, re-styling everything at the same time. Both the YDS7 and YR5 (250/350) were already very close to the proposed

RDS, but the CS3E was still aesthetically stuck in the ’60s so a re-styling was needed. The resultant CS5E was essentially a foretaste of the coming RD200 with differently profiled side panel/oil tank minus the reed valves. The 200 twin was a firecracker on wheels and a total riot to ride. Whatever Yamaha had done to the porting inside the all-new barrels, they had enlivened an already surprisingly fast CS3E. The CS5E fair flew when it came on pipe, with the front wheel getting rather flighty without too much effort and pawing the air if you were so inclined. If Yamahas had always carried a little racing DNA inside them then this one received a rather generous helping. Although the 5 uses the same pistons as the 3, something just a little special had been done inside the cylinders. Despite the fact that neither brake horsepower nor torque had changed between the two models, the CS5E always felt sharper, faster and more of a miniature racer on the road. Unquestionably a child of the 1970s, the bike followed the Yamaha Europa range family tradition with an intense candy colour set against a flat neutral one. In this instance, the bike’s designers went for a mid-shade of purple offset against a slightly creamy white, but with one rather strange difference. Everything, without exception, in the Europa range ran the standard format of the candy paint being the dominant colour, with the flat neutral

as the recessive one… apart from the CS5! For reasons no one can clarify, Yamaha sold the bike in both purple over white and white over purple, essentially each being the negative of the other. Neither is right or wrong, and those that collect the smaller Yamaha twins have their own favourite. However, carry out an internet search for the CS5E and the white over purple version does come up more often. Interestingly, all the factory literature shows the white over purple schemes so who knows how the reverse scheme came about? It’s also apparent that the model was essentially only a fill-in between the CS3 and the RD200. Loathed to tool up for a short run model, the CS5 runs plain decals on its oil tank and side panel, in contrast to the likes of the AS3 125, YDS7 250 and YR2 350 that sported substantial chromed plastic flashes. Neither could Yamaha be bothered to revise the chassis prefix stamping: all CS5S start off with the CS3 prefix. To say the CS5 is a rare bike might be an exaggeration, yet they’re certainly not common, and despite being almost an afterthought, many Yamaha fans regard the model as one of the firm’s most elegant twins. Graced with stunningly good brakes and a chassis that remained fundamentally unchanged from 1968 through to the early 1980s, the bike handles better than many of its peers. Yamaha’s CS5 may very well be a perfunctory postscript to the pre-reed-valve machines, but it is one hell of machine and pretty as a picture, too.

Check bases for rot. Seat foam often degrades with age to a crumbly mess. The stainless steel trim is almost impossible the find. One-piece systems prone to stress-induced corrosion at barrel joint: ensure fit correct at port, then tighten up the lower Wayward handling may be down to loose engine bolts. Check the two bolts at the back of the engine and the four at the front engine plate. Thread locker helps. Robustunit, but bikes that have been standing may possibly need new main bearing. Listen for dry growling noises. Poor running may be due to cracks in the heat insulators inside the carburettor’s front mounting. Unhelpfully, Yamaha never listed it as a spare part.

Poor starting and/or charging generally down to contacts inside the gold-coloured box under right-hand side panel. Carefully clean and adjust as per factory settings. The dynamo also doubles as a starter. Ensure brushes aren’t worn out. Ignition timing must be set with advance/ retard unit spragged fully open. Just like all contemporary Yamahas, ports in pistons are poorly finished. Dress sharp port edge to avoid cracking between ports and gudgeon pin bosses.

Punchy for its cubic capacity.

Rewards are just before the red-line.