BUILD FEATURE THE PILEDRIVER PROJECTTURE
Ah, if the otherwise pretty unburstable CB/SL350 motor has one Achilles heel, it’s the cam
chain tensioner. Rather than a slipper, Honda used a pair of rubber jockey wheels, similar
to the early CB750s. Over time and repeated heat cycles the rubber becomes brittle,
then starts to break up. Which is exactly what’s happened here. Replacements are still
available; the larger wheel is a mere £5.95, but the smaller one only comes with the metal
support and costs a whopping £49 plus VAT! Gasp.Which indeed it turned out to be. In fact, they were so well stuck I had to prise each plate
apart with a screwdriver, and you can see just how well the friction plates had attached
to the plain steel. Rubbing both sides with a bit of emery cloth solves the problem, then
both sets of plates were washed off in petrol before refitting. Doesn’t look like much, but
just sitting and getting all those plates clean took the best part of half an hour in itself –
one of the reasons why professional rebuilds cost so much by the time they’re finished.The left hand plug thread is even more butchered than this photo makes it appear.
Close inspection of the barrels revealed that this was the source of the water ingress,
it had dribbled past the loose fitting plug, and past the stuck rings and down the bore.
Fortunately, without doing too much damage, the bores look like they’ll hone out and live
to fight another day.Most of the piston rings were also stuck – the best way to unstick them is to add some
heat, then gently tease the gaps with a small blunt screwdriver. Repeated (and very care-
ful) applications of the above eventually saw all six rings free and easy, at the expense of
only a few burned fingertips. A gap test saw them just at the upper end of tolerance, so
the plan was just to hone the bores and refit everything as standard...Several reasons for pulling the primary cover off. Firstly, it holds the centrifugal oil filter,
so that can be stripped for cleaning out. Secondly, I wanted to check the oil pick-up
strainer, it’s not unknown for bits of rubber camwheel debris to cause partial blockages,
and thirdly, the longer a bike’s been stood, the more likely the clutch plates will be stuck
together, so separating them out is usually A Good Idea.The clutch pushrod was
bent and wrapped in tape
where it went through the
damaged oil seal in the
casing. Both easy fixes,
a few taps with a rubber
mallet and a new seal in
the post. The lifting mech-
anism was also worn,
though. As the cable
pulls the arm, the centre
rotates on three balls
and pushes out against a
three-section ramp. But
the centre was a worn
and very sloppy fit in the
casing. Luckily I had a bit
of brass shim the right
thickness, so I trimmed it
to size and fitted it, before
reassembling with lots of
lithium grease. At least
one fix hasn’t cost me
anything then.You can’t win ‘em all. The advance/retard unit was seized solid. So solid in fact, that
despite getting it nearly glowing red, it still wouldn’t budge. In the end I broke it trying. Ho
hum. That’ll be 30 quid on its way to the States for a secondhand one off eBay....but then I saw these 3mm oversize Hap Jones items on eBay USA... Oh heckers...98 | 100% Biker | issue 250 | http://www.100-biker.co.uk