Yamaha RD250LC Rebuild and Review … and you could win one!

Yes, you can win this little slice of motorcycle history – Yamaha’s RD250LC – courtesy of Bennetts and BikeSocial. But what was it that made the RD250LC so special?

Yamaha RD250LC history…

Back in the early 1980s, this was where it was at if you were new on two wheels: a ‘race-developed’ (RD) liquid-cooled (LC) two-stroke of some 247cc pumping out 36bhp. Yes, we know the big-brother 350LC would garner all the glamour over the coming years and decades, but remember that in the 1970s and early 1980s, learners could ride sub-250cc machines and that meant you could finally crack 100mph on L-plates… Sure, some claimed Suzuki’s GT250 X7 could do that, but – to be fair – not without a fair wind, a dodgy tune-up whilst going downhill…

When did the Yamaha RD250LC appear in the UK?

In Japan the RZ250 appeared in the first months of 1980, but the UK had to wait until the May of that year for the RD – despite the 250cc market in Britain being one of the most popular – thanks to those learner laws of the time…

When it finally hit our shores it literally made the opposition obsolete overnight, but to be the L-plated king ding-a-ling, you’d be paying £1030 for the privilege – which was a few hundred quid up on the other learner-friendly two and four-strokes available at the time making it the only 250cc machine to bust a grand.

Stripping and rebuilding an RD250LC; everything you need to know

Daryll Young of IDP Moto gives Bertie Simmonds the low-down on how to rebuild a classic Yamaha

What’s the difference between the Yamaha 250LC and 350LC?

First of all, the 350 turned up in the UK a month later than its little brother and by then the order book was full: 10,000 had been pre-ordered across Europe since the bike was seen (along with the 250) at the Paris Show in the Autumn of 1979.

Both the 250 and 350 were developed side-by-side and were the same physical size, as they shared many of the same components. The side-panel stickers would give you the biggest clue, as would a single (250), rather than twin (350) front disc brake set-up. As both bikes had identical ‘italic’ wheels, a plastic cap was fitted on the left-hand side of the front wheel, there was also a different brake master cylinder, too. Still at the front of the bike, the 250cc LC had a single horn, rather than the two on the 350.

At the rear of the bike, the rear sprocket had two more teeth on the 250 and while the 350 had segmented rubber cush-drive in the rear hub between the vanes and the sprocket mounting plate, while the 250 had individually cushioned sprocket mounting bolts. Of course, the biggest differences were internally in that the water-jacketed barrels had 247cc of space inside, not 347cc, complete with different pistons, cylinders, cylinder head and exhaust. The bottom-end was largely the same hence many 250s were later converted to 350s, often sold without telling that to the new owner… naughty! The 350’s 4L0 designation is prominent on engine/chassis numbers while the 250’s is 4L1…

Of course in terms of performance, the 350 was pushing out 47bhp at around 8500rpm with the 250 pumping out a more modest 36bhp at the same revs. To pay for the extra power, you’d spend £100 more on the 350 over and above the 250cc machine’s £1030 price tag.

Think about it for a moment: you’re a learner in 1980 and you get a four-kilo lighter machine, offering more than three quarters of the performance of the 350 for almost 10 per cent less outlay… This made the RD250LC a winner.

Death of the Yamaha RD250LC in the UK

It was the ultimate irony that the learner laws that prompted the RD250LC’s success in the UK would also be the catalyst for its demise.

To have a learner motorcycle capable of 100mph made those in power a little uneasy, especially when looking at accident statistics for learners on two-wheels. From the end of 1982, the law changed to restrict learners to 125cc machines capable of no more than 12bhp.

This killed the RD250LC and its peers pretty much overnight, even if the bike itself carried on in Yamaha’s range until 1986. By then the class was re-inventing itself as a cutting-edge performance class, almost mirroring that of the 250cc GP bikes that were racing. And – of course – the RD250LC was by now well outclassed by newer tackle.

The Yamaha RD250LC today…

Today you’ll be hard pressed to find a basket case, even if both the 250 and 350LCs were popular production race bikes: many of these have long since been snapped up. Of the bikes that are unmolested, the original source of such machines would be Europe. A legend in the RD community ‘LC’ Kev Schofield reckons the last of the un-adulterated German bikes are long gone. He says: “Bikes have dried up and also become harder to find and import, thanks to the likes of Brexit and COVID-19. I’ve had about 600 bikes from Germany in my time, but this source has pretty much disappeared. My tip: look towards Sweden for good RDs.”

Back in 1990s you could pick a 250LC up for a couple of hundred quid, really nice ones were below a grand: even back in 2013 Niall Mackenzie (former owner of this 250) picked up a tidy 350LC for £1800. Today nice 250s start around £5000, finding a really good one means paying north of £6000 and up to £8000-£9500 for a minter. Instead, may we suggest you join us and give yourself the chance to win this, 1983, 35,000k, unmolested example: this bike –Niall Mackenzie’s old bike – is up for grabs: but first let’s strip it, check it for any issues and give it a bit of a once-over for you…

Above: Niall Mackenzie gets all nostalgic ahead of the PRO-AM series back in 2015

Yamaha RD250LC strip down: first impressions…

We knew where to go to give our RD250LC the once over: IDP Moto in Silverstone. There, Daryll Young has seen the guts of more RDs than he cares to remember. Not only has he owned them and raced them himself, he also put together a fleet of 30 RD250LCs for the reinvented Pro-Am series of 2015: he knows his stuff.

First off we fire her up and she starts after a few kicks, sounding and smelling just like an RD-LC should. Daryll says: “What’s good about this bike is that she’s a matching numbers, unmolested RD250LC. Everything is there and original – of course it’s 40 years old so some things have been replaced. Some bolts have changed and I like to go back to standard. The foot-rests are worn and on the mounts the plating has gone on them. The frame looks pretty good – you don’t want to strip it down and blast/powder-coat it, there’s no need. The barrels have been blasted though – they should be black and we will re-paint those.”

There is some evidence of age and action, such as the scuffed clocks with faded logos. Daryll says: “It’s hard to get MPH clocks but we may replace the clock shells and the trip re-set knob: also some parts around the clocks have rust on them and I like these parts to look new. Indicator bolts are not correct, so we want to replace with originals. The headlight shell is not original, but looks OK, but with a yellow pilot bulb – we will change this! The headlight brackets can be powder-coated when we do the engine covers… We will tidy up the foot-rest mounts as mentioned, as well as the foot-rests/rubbers/bolts: the tie-rod can be replaced and the incorrect rad-cover bolts need replacing too. We’ll clean and powder-coat the kick-start and torque arm and the grab-rail needs to be chrome. Mainly it’s some cosmetics on this to take it up another level for the next owner from Bennetts BikeSocial.”

Yamaha RD250LC strip down: checking the basics…

“This is almost a mini-MoT check before we strip the bike,” explains Daryll. “So, we check that the wheel bearings are OK, that the head bearings are OK, and that the brakes aren’t binding on and that the fork seals aren’t leaking. Make sure the wheels are running free, no play in the wheel bearings, no notchy/loose feeling from the head bearings and look at the swingarm too. The forks look OK and they can pit easily, but you can get new parts to replace them: I can see a little bit of rust on the top of the left leg. Just with these few checks we can see this bike has been pretty well looked after. Being a German bike it is standard – which is good, as you’re not allowed to change things. In the UK so many of the bikes were almost butchered in a bid to make them unique to the owner! The big thing you can see is that the bolts on the engine aren’t original and that’s a common thing as many owners didn’t have the proper tools so they will chew the heads up and replace them with Allen bolts: it costs next to nothing to change this back. With that mileage it will have had pistons and rings, we just want to give this one a tidy up so it’s smart, presentable but more to the point useable.”

Yamaha RD250LC bodywork strip down…

Daryll says: “Let’s have a look under the tank, panels and seat, seat first: it’s quite common for lugs to be broken, but this one is fine. I would guess it’s had a new seat-cover. The tool kit has gone – that doesn’t surprise me but you can buy these new. Wiring looks good under there too… You have to be so careful removing the panels as they can crack around the grommets and the right-hand panel is normally cracked – as you need to remove that more often for the oil-tank, but this one is fine.”

Apart from the normal issues with bikes laid up with fuel in the tank (rusting) the fuel taps tend to seize up and leak fuel into the crankcases on RDs. The thing to do is replace the fuel-tap with a pattern one – Tormax ones work best, according to Daryll.

“It’s good to see this has the original rear shock with original sticker on it,” says Daryll. “If the shock still works we’ll clean it and leave it as it is. Also we can see the air-box is standard and not drilled full of holes as a performance modification! The cover over the coils is missing near the headstock – that’s common. People try and 3D print them but it doesn’t work. Those iconic italic wheels are in good condition and just need a clean-up.”

Yamaha RD250LC engine strip down…

Starting with the exhausts, Daryll mentions a few things to watch out for: “These exhausts are notorious to get to seal. They have two gaskets: one gasket in the cylinder and one in between the flange and cylinder. Often these are bodged and can rattle loose but these are sealed quite well. You’ll often find exhausts can weigh a bit more than normal as they’ve been filled or are full of carbon, but these are in pretty good condition, although the right-hand one has some damage on it.”

Time to drain the coolant, let’s get the radiator shroud off first. Daryll explains that - considering this would be marked in the event of a crash you’d think they could be rare as a result – but you can still buy them from Yamaha for around £70. “We’ve got a few of these sat on the shelves. Draining the coolant, we can see it’s pretty fresh and nice and clean – always a good sign, head off next, remembering to crack the bolts off from the centre, in sequence.”

Daryll adds that the original metal covered plug caps have been replaced: “The originals would arc out over time and weren’t great, so these waterproof NGK ones are better. The bolts should be olive green, so we will replace them. We can’t get the original finish but can get them close. The original process was nasty and used cyanide, which you can’t do now for obvious reasons.”

The head is finally removed and Daryll is happy: “There are no signs of any damage or issues here, looking into the barrels the pistons look clean and it seems it’s had a recent re-bore in the last few thousand miles. This is good for us and the new owner.” Carbs look good too: “These have come off easily. The carbs can get blocked hence people ultrasonically clean them. We’ve heard our bike run sweetly, so these just need a clean in the hot washer and the replacement of some parts, such as the tick-over/air-screw. We will check the floats and needles too, but this one hasn’t been leaking fuel.”

The barrels are now off so we can have a good look inside the guts of the RD and Daryll is still beaming. “That re-bore does look fresh: the size is 54.5mm or thereabouts, so it’s on its second oversize (0.5mm) which is good. You can go to 2mm over on these. There’s also no movement on the little-end bearings so there’s not point going any further now with the motor.”

Yamaha RD250LC brakes strip down…

Despite the brakes not binding on during our initial look-over the RD, Daryll did find a few things amiss. He said: “You can see the piston in the caliper isn’t in a good state and it’s been attacked with some pliers and is stiff. We may as well strip and rebuild it, new seals and piston: even the pattern caliper rebuild kits are good. The pads are fine but cheap enough to replace and we will paint the caliper too. Niall Mackenzie put on original rubber lines, which is nice, but at some point someone has snapped the mounting lug for the hose clip on the right fork leg and replaced it with a split-pin. We may have to replace the whole leg as we want to do the right thing by this bike and the new owner.”

So, that’s it… Daryll is impressed with the condition of the BikeSocial Yamaha RD250LC and is now in a race against time to ensure it’s ready for the London Motorcycle Show at ExCeL, in London over the weekend of February 11-13. The competition is open to every BikeSocial Member by clicking here, but be warned, it ends on 31st March 2022.