There are two distinct and separate ways of looking at the RS250. The first sees it as an eminently usable device with plenty of power and delightful handling. The second view sees it as a good idea spoilt by poor detail design which makes it a very dubious secondhand buy.
Of course, the truth is that both views have equal validity. when it's running well the RS is a great bike to own, when the various faults rear their ugly head, it's a pain in the arse. That so many people are so loyal to the things, just goes to show how good they are when they are working properly.
The RS engine is one of those quirky designs that Honda so favoured in the late seventies and early eighties. It shares a lot in common with the 250 SuperDream. The major problem comes from Honda's old trick of having the bearing surface for the camshaft as part of the cylinder head. By twenty grand the surface is worn out. Good heads are hard to find in breakers, while some of the machining shops that fit sleeves in the head don't do a very good job.
Other problems come from camchain and tensioner at 18000 miles, piston and bore wear at twenty five grand, and balance shaft and chain wear at any time it feels like giving trouble.
For a single cylinder engine, the RS is very complex with too many valves, exhaust ports. balance shafts and quick wear chains. The result is an engine that is not very economical but can have a surprising turn of speed.
The bike averages 60mpg. The best that can be achieved is 80mpg, but this requires moped speeds, so isn't really relevant. Thrashing the bike along at maximum revs and illegal speeds gives just 50mpg.
Because the RS has a decent riding position, with well placed footrests, flat bars and usefully shaped tank, it can be cruised at up to 80mph. At such speeds the balance shaft doesn't do much to absorb the vibes and it becomes quite intrusive with a few thousand miles wear. It doesn't do much damage to chassis components. With just 300lbs to flick around the handling is jolly nice for most of the time.
The engine is used as a stressed member and helps give a rigid feel to the chassis. The shocks are the usual throw-away junk, the forks are OK when new but get floppy and imprecise after fifteen grand. There's plenty of feedback from the road to make wet weather riding pleasant.
The front disc is the usual rubbish. The calipers seize up on their sliders after eight grand, pads last for 7500 miles and stripping down the brake is about as much fun as selling used bikes in Cardiff. The rear SLS drum is nothing to write home about, with a disturbing tendency to lock up without warning. Rear tyres go for ten grand, front for twelve, chains last for around 10000 miles.
The RS seems to appeal to the same kind of people who buy MZ250s, who will probably be used to indulging in frequent maintenance and engine strip downs. The comparison with the MZ is also pertinent because both bikes have a nice feel out on the road and a great deal of versatility. The RS can be screwed along the motorway fast lane, hustled along country lanes with the best of them and rushed through town with the ease of a trail bike.
It's just a pity that there are so many mechanical problems to overcome to enjoy the Honda properly. It's possible to get hold of 1980 or '81 bikes for around £100, but they are going to be in quite a bad state, unless you're very lucky. Try to find a bike relatively free of vibration, as this is as good a guide to a decent bike as anything. Any engine noises should be viewed with grave suspicion.
If you don't know anything about engines, avoid this one.