Just when the world got used to 250s being the ideal trials capacity up popped the 325 Sherpa.
We have an in-depth look at the 325 Sherpa, Bultaco’s answer to those who wanted more… more… and yet more.
If you’re going to have a 325 Bultaco restored then it is possible the workshops of the man responsible for its inception could well be the place to go. Alongside the Sally Miller Museum is a wellequipped workshop where all sorts of magic happens and machines from the dawn of motorcycling time are resurrected for display in the halls. The team… Bob Stanley and Sammy himself… are hands-on restorers and occasionally dabble in customers’ machines, as well as museum stuff.
It is to Bob to whom we turned for information on this particular restoration, which was completed at quite a rate of knots. It did help the bike was all in one piece and didn’t seem to have been abused in its life. Said Bob: “Sometimes a bike does escape the fate of many trials machines and gets pushed to the back of a shed or garage and is then not looked at for years rather that than be passed on until it’s being raced round a field shedding bits left right and centre.” He continued: “The more we looked at various bits the more it seemed to bear out that theory though it did need lots of tlc.”
Taking the frame as the starting point it was checked over on a surface table, measured up and all datum points noted, it was found to have a ‘straight’ frame. “We did put new swinging arm bushes and then sent the whole lot off to be powder coated in...” there’s a pause here while Bob ruffles through the build notes... “coated in…aha… Ford Silver Fox which is the closest we can get to the original colour.” A set of steering head bearings pressed in finished the frame and once the fork yokes were polished the corresponding inner race was pressed over the stem for the lower bearing and the top one slipped. The frame was ready to go.
Forks tend to suffer a lot of abuse on offroad bikes and the hard-chromed stanchions were quite badly pitted so were stripped, ground true and re-chromed. Don’t mistake the chroming used on stanchions to be the same as decorative plating used elsewhere on things such as gear and kick-start levers, it isn’t it’s an engineering process and allows fine tolerances to be built up depending on how long the stanchion is in the plating bath. In this way any slop in the forks can be cured. The alloy sliders were vapour blasted and polished, new seals were fitted, the stanchions slipped in, the bottom bolts tightened to locate the damper rods and a set of new springs went in the tubes, along with 150cc of oil in each leg meaning the forks were ready to fit. Suspension restoration at the other end involved re-
chroming the springs and painting the bodies of the dampers.
Bob carries on speaking about the wheels. Bultaco championed a hard chrome plating on the insides of the drum for a braking surface. Depending on who you speak to it’s either a great surface or a ridiculous way to finish the inside of a drum. Problems start when the chrome peels off and starts ripping the brake shoes apart, then the braking goes and something has to be done. Luckily for the owner of this bike the chrome was deemed good and left in place. Had it not been then there are two options, pressing in a cast iron liner with an interference fit or metal spraying the surface. The former can be done with the wheel fully built while the latter needs it stripping down. “Once we found the chrome plate was okay we just needed to polish up the original rims, fit new
bearings and lace up the wheels with new spokes. The brake plates were polished and new shoes went in.” Anything else, “Oh yes, the tyres were perished so new ones and tubes and security bolts too were fitted.”
At the time this Sherpa left the factory, in 1974-75, Bultaco was still using alloy mudguards with a distinctive shape and rib. The original rear guard was salvageable… eventually… but the front guard was too far gone but luckily it seems the tooling Bultaco used still exists and new guards made using it are available now.
Stripping the engine on a bike as old as this is always an interesting experience. On this one the crank and big-end were fine enough to reuse as was the piston, all the bearings inside the engine were replaced as a matter of course and the biggest task was de-gumming the gearbox. “The old EP oil had emulsified in the box and it had left a tide mark on the inside of the cases, so we cleaned it all out and found the bits to be pretty un-worn. All the clutch parts were fine too. We just put a new chain on when we rebuilt the engine as well as new crank seals as the originals were like wood,” laughs Bob, adding: “I’ve seen some seals go hard before but this was way past that.” The finish on the engine cases, barrel and head are a combination of blasting, vapour for the polished parts and something slightly more aggressive for the painted barrel. “Once the outer cases were blasted, we had them polished and they look fine now.”
Electrically speaking new points and condenser brought the sparks to life and assembly could begin. Bob also added that the various levers were chromed and the fasteners were zinc plated – zinc being the ‘new’ cadmium and a less-poisonous substance.
We’ve left the tank seat unit until last for good reason, it’s glass-fibre and the stuff which passes for petrol these days doesn’t react well with it. I wondered if the insides had been treated with a sealer but no, it seems there is ethanol-free fuel available if you know where to look… “No I don’t, before you ask.”
The tank was rubbed down and re-painted in the smart red scheme Bultaco was noted for. To finish the unit the seat was recovered and fitted back in place, to make a good job superb.
The final task was to fit new cables all round and then the bike was ready to go.
Words: Tim Britton Pics: Sammy Miller Museum The ultimate weapon in the Seventies. Wonder what happens if we put the flat tracker piston in here?
Brakes are still on the proper side at this time. Glass fibre fuel tanks were outlawed for road use in the UK. Exhaust routing is tight.
It wasn’t just the editor who was smitten by this Spanish beauty...