Su­per Profile

Just when the world got used to 250s be­ing the ideal tri­als ca­pac­ity up popped the 325 Sherpa.

Classic Dirtbike - - Contents -

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...

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.