Yamaha YZ250R

Yamaha YZ250R Road Test




Yamaha YZ250RThe Yamaha YZ250R road race bike

Most things in racing are born out of necessity and none more so than this particular motorcycle. Way back in the late 70’s racing was hot and competitive. Young lads were hurling stock RD’s around the UK race tracks with gay abandon (trust me it did not mean the same then) and there was very little preventing the top club and national racers from entering the GP circus within a couple of seasons. The general feeling was one of optimism as very little was put in front of you preventing your progress, certainly not the politics and vast financial requirements found in racing today.

Yamaha announced the arrival of the 250 and 350 LC’s in the winter of 79/80, I had actually seen the prototype bikes during the summer of 79 although they bore little resemblance to the final version that hit the showroom floors the following year. The LC was going to be a quantum leap in the world of proddy racing with its water-cooling and monoshock suspension, it just had to be the bike to have. The only problem was the first ones to arrive were going to be way too late for the 1980 season, with my previous years RD400 already sold, I for one did not want to miss any racing and sit it out on the subs bench.

YZ250R EngineIn the absence of any other machinery there was only one option while we waited for the LC, and that was to race something very cheap as a stopgap measure. The answer sat in the corner of my sponsors showroom looking very capable of it’s intended purpose, the only trouble was it was a different purpose than the one I had in mind for her. She was a brand new, but no longer the latest thing, 1979 YZ250 F Motocrosser and the plan was to convert her for single cylinder racing as frugally as possible.

That evening the air-cooled YZ was transported to my home ready for the conversion, nothing was committed to paper throughout the work, and everything was created as a rough sketch and then straight to metal. The whole project was going to be carried out at my parents house in the 4’ x 6’ “Potting shed” located at the bottom of the garden. The massive front forks were the first to go, replaced by a pair of RD250 B tele’s, these served to drop the front considerably and steepen the head angle. The only modification necessary was to swap the RD bearings for the YZ taper rollers and the rest just slotted together. The RD front wheel was also used complete with it’s TZ like disc brake. The plastics were put back into stock at the Yamaha dealer along with all of the other unwanted parts, these parts alone, being classed as consumables and always in demand, were eventually sold covering the initial cost of the bike.

YZ250REverything used to convert the bike was second-hand apart from a new pair of 18” Michelin PZ4 tyres, so the cost was very low indeed, certainly no more than a few hundred quid, if the parts had been sourced from a breakers yard. An after market aluminium RD petrol tank fitted almost straight on as did a TZ350 seat unit. The TZ350 E fairing was not so easy however as the original crosser pipe travelled up the front of the left side and across the top, exiting just under the seat. This meant that a large hole had to be cut into the fairing and in the absence of things like a Dremel back in those days meant lots of cutting by hand to get it just right. The bike was so short in comparison to proper road race bikes that the screen and upper parts of the fairing had to be reduced in size to enable me to get behind it, once again a treacherous job armed only with a hacksaw blade.

A pair of loops were fabricated out of Reynolds 531 tubing and welded onto the lower frame to facilitate the mounting of rear sets, while at the front, a fairing mounting stem and a lock stop was also welded on to the front of the headstock. Clip on handlebars finished off the racer look and an RD master cylinder provided the necessary pumping power for the front master cylinder.

YZ250RHaving already committed to using the crosser rear wheel, an effort to save time and cost, this provided us with a lovely wide alloy rim and adequate drum brake set up that needed no extra time or work leaving me free to concentrate on the rest of the bike. The original fitment 52 tooth rear sprocket made way for the smallest gear wheel that would fit onto the YZ wheel hub, a specially made 36 tooth affair that still required a little bit a metal removing from the hub to stop the 520 chain catching.

Everything that I deemed unnecessary was taken off and put back into stock leaving us with a very bare looking machine indeed. The airbox was the last item to go to be replaced by a piece of rubber matting across the rear frame members to stop stones and the suchlike flying off the rear wheel into the massive 38mm Mikuni carb. The standard CDI ignition was left in place and, despite recommendations from many to rig up some kind of tacho, I never actually bothered with one. All in the entire bike weighed in several pounds lighter than the standard YZ, even with the race fairing attached.

Yamaha YZ250RBy now, exactly a week after the project started, the bike was starting to look quite business like, even though the brand new YZ engine had yet to be started. That opportunity came on following the Wednesday afternoon at a local airfield. My friend and team mate, Wayne Mills took his TZ125 Yamaha along to compare it with the YZ, back then the 250 singles mainly ran with the 125 class so it was a good comparison, I also rightly guessed that Wayne wanted to assess the potential of the YZ in the process. Back then most races were started with a dead engine so it was crucial that the big two-stroke single could be push started alone, I spent a while perfecting that technique while Wayne warmed up the water-cooled TZ125.

Initial acceleration of the YZ was far superior to the Pukka TZ racer and top speed seemed comparable. Providing no attempt was made to over rev the single and the next gear was punched in early she kept on pulling, producing a real threatening droning sound as it accelerated through the box.
Back home after that initial test and I was fired up with enthusiasm, a few phone calls that evening got me a ride the following Sunday at Cadwell Park. The rest of the week was spent painting the fairing, and applying sponsors logo’s and then it was loaded up ready for the off.

Yamaha YZ250R - Cadwell 1980At the track, practice went well and no further adjustments were deemed necessary, although it rained all day, and being too young to ride on the road, I had never ever ridden in the wet, to say I was bricking it would be a gross understatement. The flag dropped and off sped the pack up into club hairpin, while my YZ droned on somewhat left behind. Once out of the tight hairpin the engine cleared and started to pull more strongly. The first race started reasonably well with me in the mid field for the first lap, I slowly picked off a few on the second lap and quickly found myself with no one to chase down. Bugga me, I was leading and real panic set in. The YZ won all of her races that weekend, as well as proving very competitive in the open classes particularly in the wet. I found the grunty two-stroke perfect for the twisty Cadwell club circuit, as I remember the singles lap record was something like 1min 17sec back then and the YZ was doing those times in the wet.

All of a sudden people wanted to look at her and discuss how she had been built, future starlet and friend Alan Carter, who became the youngest ever Grand Prix winner the following season, blagged a ride up the paddock road. When he returned from his several wheelie ensconced runs up and down the road he knew how I had been able to hold my own against his Pharaoh Yamaha’s.

Yamaha YZR250R - Mallory 1998After a few meetings the deep treaded Michelins were getting tired from all of this super high speed cornering stuff, so they were replaced with very soft compound Dunlop’s, a five-inch KR124 was fitted to the rear, and a triangular KR96 to the front. This combination was nothing short of awesome as the rear would slide controllably under power and the huge contact patch of the front simply refused to let go, the tenacious grip allowing me to brake fully even at full lean. In fact I never fell from the YZ in over thirty meetings on her even though she rode around, under and sometimes even over any thing in her way. She was, and still is a great machine. The YZ attracted quite a bit of interest from the press of the period with several articles appearing about the old gal and her successes.

The following season arrived and my plans had changed completely, I had missed the first half of the year due to a badly broken leg, (skiing not bike racing) I no longer required an LC as a new TZ250 had been purchased and the open class and beyond beckoned. I ran the YZ alongside the 250 TZ at club level for a while, and the crosser made a good back up bike especially if it rained. If I had stopped on the TZ like I had the YZ then I may well have followed Mr Carter into Europe but alas, the TZ and I spent much time looking at each other, usually whilst spinning up the track. Compared to the TZ, which seemed to literally eat parts, the YZ cost very little maintenance wise; in fact I only ever fitted one set of rings in two seasons racing.

I made a further two versions of the YZ for other racers in 1981 and the original YZ was also sold during that season.

Yamaha YZ250R EngineThat was the last I saw or heard of the YZ until an ad in MCN caught my eye some seventeen years later. It read “YZ250 single racer £285 ono.” I phoned and arranged a meeting with the owner, imagine my surprise when it turned out to be my old bike. She was a wee bit forlorn sitting in several boxes completely in bits. Lots of little parts were missing but the welding on the frame was definitely mine, nobody welds like that, believe me, although, so I am told, sparrows do a good impersonation.

A bit of fast-talking got my partner to “agree” to a “low cost” restoration project to get the YZ back into it’s original condition. “Honestly dear it will only cost a few quid, honest”. Back at the ranch and the project was laid out on the workshop floor to be assessed. She had gained a few go faster mod’s in our time apart, now sporting Astralite wheels, rear disc brake and a Motoplat ignition. The major problem was the lack of exhaust pipe, an original genuine Yam one was still available, but the list price of £700 was not in keeping with the intended project so I had to give up the idea of a faithful reproduction, opting instead for a low slung pukka race pipe made by Abcon at Nottingham. Dimensionally the new pipe is the same as Barry Sheene’s TR750 Suzuki racer but to fit this length within the dimensions of the short MX chassis meant the tailpipe almost sticks out illegally beyond the rear tyre, that is why the original YZ pipe twisted and turned around the frame in an attempt to absorb the length and keep it within the rules.

The engine was completely rebuilt as was the chassis parts and what we ended up with was a very pretty and functional looking motorcycle indeed. Imagine my delight when the FRC club announced the introduction of a singles class for the 1998 season. A wee bit more fast-talking convinced the better half that it would be a real shame if the old YZ never got to run on a circuit again. “I think” she agreed that I could have the one outing on her.

Original 1980 Yamaha YZ250R Magazine ArticleLuckily push starts have long gone for all but a few classes, so the YZ could be started with the engine running. Thank god for that as I was feeling my age even if the YZ wasn’t. That first meeting in 98 showed that the old girl could still give even a modern 125 machine a run for it’s money and the year ended with the vintage MX bike winning the singles championship outright. Consumables were not a problem and Yamaha UK could still supply pistons, rings and gaskets from stock, this proved the YZ to be a real cheap clubman’s proposition even today.

She has not been run since that 98 season and now stands proud in my office as a testimony to what can be achieved if you are deep enough in the brown stuff. Just as a matter of interest it was always a few mph quicker without the fairing on and the left hand holding the fork tube, flat track style! Unfortunately that left us with nothing to mount the all important sponsors logo’s so a fairing was a must.

Yamaha YZ250R Gallery

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