FOAK:Honda CB 250 RS

were they any good?
Thinking of buying one for the 20 mile round trip daily commute.
anything to look out for?


Dave

 

can't remember if there is anything to look out for but the one i had was
100% reliable, great fun, v good mpg and went fairly well for a 250 single,
buy a decent one and i'll be suprised if you have any cause for concern.

 

dave eades says...

I used a 170,000 mile one for a 100 mile a day flat out commute down the
M1, M25 and M4. It wasn't happy doing it, but it managed it. I then
retired it to a 50 mile a day commute, which it was a little happier
with.

As long as the cam and camchain don't rattle, it's had very frequent oil
changes and the mileage looks right then buy it. Other than that, check
the condition of the rear sprocket cush drives. They have a habit of
wearing out and wrecking the rear wheel hub. As does the large circlip
that holds the rear sprocket in place. If the rear sprocket has sideways
moevement then you'll have trouble repairing the groove it sits in and
the chain will wear like buggery. Everything else is straightforward and
the type of things you'd check on any used bike. Just bear in mind that
the CB250Rs doesn't have an oil filter as such, so frequent oil changes
are very important.

 

Steve Dixey says...

What bearings? The cam sits direct in the head.

 

Perhaps he missed a "a lack of" in the sentence.

 

The cam running directly in the head is common to all the models and clearly
a weakness in the design. Cheap oil, infrequent changes or low level can
cause permanent damage.

The cush drive and chain wear problem was solved with the RS-D, along with a
few other niggles. Only issue was they took off the kickstart and added an
electric start with a poor engagement mechanism (sounds like an old Ford
Cortina). Anyway the electric start is fine if the bike is used everyday
and the battery is in good condition - otherwise it's trouble.

There is a way to put the kickstart back in an RS-D but it does require a
little engineering. My sister did it on her CL250 (same engine) with great
success. She was talking about putting some instructions together but, as
she's in the middle of moving house, this isn't likely to be top priority.

 

Yep, same with my Bandit and my FZR.

 

I had an RS-A for a few year - did about 24K on it and sold it at
about 48-50K miles and the engine was still going strong.

I *think* I replaced the camchain early on but ISTR that this was a
precaution really as it was getting near the limit - I never really
trusted the odometer reading.

The alternator died once: replaced from a breakers. Rear wheel
bearings went; rear sprockets were always loose due to worn hub/clip.

It was not fast: it struggled to make seventy into a strong headwind
but it was economical.

The auto-decompressor never worked becaues the cable was seized and
the cam arm inside the RH case had broken off, but it was always easy
to start.

It was comfortable: I once rode with the then GF to Loch Lomond on a
camping trip, and several times commuted to Sheffield from Newmarket
on weekends.

Oil must be changed regularly because there's no proper filter.

I got through one pair of aftermarket shocks during the time I had it.
Oh, a couple of rear wheel spokes broke, but that could have just been
bad maintenance on my part.

The only other mechanical problem I can recall was when it started
fading and misfiring on cold damp days after about ten minutes on the
A14. It had never suffered this before. These days, people would shout
"carb icing!" but I'd never heard of the condition back then.

After much head scratching I found that the carb float chamber
breather was clogged. Once I'd taken it off and cleaned it, the
problem went away. To this day I don't know whether it was the
breather itself, or whether in cleaning it out I also cleared
something else, maybe the main jet feed.

Oh, yes, just remembered: I *think* I've still got a spare rear wheel
and possibly a LH engine cover (no alternator, though), if anyone
wants them.

 

You probably had some water in the bottom of the float chamber that was
freezing in these conditions.

 

If it was in a position to cause trouble, I'd expect it to be more
trouble as a liquid because it could then get sucked into the main
jet. As it was, I don't recall finding any water in the bowl.

 

Not always obvious, it usually looks like a small orange/brown (rusty)
maggot swimming around the bottom of the bowl, if you take the time to look.

 

I know what water in the float bowl looks like.

Like I said, if there's water in the float bowl then it'll cause
problems as soon as the petrol starts getting drawn in quantity into
the main jet, not several miles into the journey, so it's unlikely it
would've been coming in with the petrol because there would've been
water contamination from the start of the journey.

It's highly unlikely it would've got drawn up and in through nearly a
foot of breather pipe, especially as it was clogged.

Anyway, the icing effect occurs at the venturi and the emulsion/needle
jet, not the bottom of the float bowl because:

a) as the petrol is drawn into droplets, it will evaporate too and
that will have a major cooling effect;

b) the venturi's job is to lower the air pressure over the jets. It's
fundamental to a gas's behaviour that a drop in pressure will result
in a drop in temperature;

c) the float bowl gets a continuous supply of fresh petrol at ambient
or more likely just above ambient due to engine heat/ rider's knees
warming the tank, so even if there was water in the bowl, I'd be very
surprised if it managed to freeze. On the occasions it occurred,
ambient was above freezing.

HTH.

 

Agree with the physics of latent heat of evaporation but I've seen frost on
the outside of a floatbowl when the ambient was above freezing; particulary
on my Morini and a friends Ducati 450.

Any water in the float bowl can freeze to crystals that get drawn into and
block jets.

That's as well as any frost that forms directly in the venturi.

The best fix, on top of cleaning any water from the carb/tank, was an
additive sold by VW agents for Beetles, as these are alos known to suffer
from icing.

 

It was somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Dave Emerson"

Methanol. Cheaper by the drum.

--

Dave

GS 850 x2 / SE 6a
SbS#6 DIAABTCOD#16 APOSTLE#6 FUB#3
FUB KotL OSOS#12? UKRMMA#19 COSOC#10

 

Well In reply to all those replies,

I went and bought it.
only problem is, there is a lttle bit of sideways movement on the rear
sprocket (chain seems OK though).
still, it managed the 60 mile trip home without any clitches,
I recieved with it quite a bit of history, and it has has regular documented
oil changes, the last one being about 120 miles ago.
It is the non-electric start version, and goes first kick.
seems good for about 70 mph, which is fine for what I want it for (work and
back, no motorways).
Overall the condition is good, the only non standard part is a motad 2-1
exhaust which look fairly recent.
I also picked up a Haynes BOL with it.
It has almost 12 months MOT and is Taxed till the end of april, all for the
princley sum of £275

thanks for all of the replies
tomorrow I shall be mainly going to work on a little cb 250 rs

dave

 

dave eades says...

Good for you. I have shitloads of 250RS spares if you ever need
anything.

 

Try using top... If you have a long enough, straight enough road and are
mechanically unsympathetic, you can get 'em to nudge an indicated 85+... I
stress *indicated* however...

You seen the prices of the std 2 into 2? The motad is a good buy...

You were ripped off, mate... Lozzo's was *way* cheaper...

Enjoy. They really are *great* bikes and shame the latest 250 jobbies (the
new CBF250 is 20-odd years newer and less powerful, for a start...)

But watch out for the chain going notchy and, as soon as it gets a tight
spot (and it will), replace the bugger 'cos when they snap they can flail
around a fair bit....

Dave

 

Frost or condensation?

Why would it get drawn into the jet only as ice crystals and not when
it was water?