Scoop’s chas­sis rolls.

Classic Motorcycle Mechanics - - CONTENTS -

There’s some sub­stan­tial progress this is­sue and only the odd im­ped­i­ment or curve ball to queer the pitch – I’m get­ting se­ri­ously worried! Ian Bird is do­ing the lion’s share of the work as I stand by oc­ca­sion­ally blind­ing him with flash guns and pre­tend­ing to help. He’s delv­ing through his seem­ingly end­less boxes of New Old Stock (NOS), lightly used yet ser­vice­able parts, se­ri­ously used but pos­si­bly vi­able parts and, fi­nally, old tat but not quite scrap yet parts. Each of th­ese has the po­ten­tial to add some­thing to the re­build. Ob­vi­ously, the crank is sorted – it’s a gen­uine amal­ga­ma­tion of new (rods/pins/ bear­ings etc) com­bined with qual­ity used fly­wheels that have been scrupu­lously cleaned. The same goes for the en­gine cases that are prob­a­bly brighter now than they were when new. The gear train for the H1 mo­tor is mainly from the used sec­tion of Ian’s spares depart­ment but noth­ing is be­ing taken at face value. Ev­ery cog, shim, shaft and cir­clip is painstak­ingly in­spected and eval­u­ated. Some might ask why we’re tak­ing a chance us­ing sec­ond-hand parts, but here’s the re­al­ity of it. Each time you re­build your old en­gine and re-use vi­able com­po­nents you are also us­ing sec­ond-hand com­po­nents. The only dif­fer­ence is you’ve used them be­fore and have a level of faith or be­lief in them. Ian’s stock has come from good mates, trade con­tacts and trusted traders. In sit­u­a­tions like we have here, NOS is not al­ways an op­tion. That said, the gear­box bear­ings are fac­tory fresh from Z Power – why com­pro­mise when there’s no need to and the costs are rel­a­tively low? Hav­ing checked, ap­proved and/or swapped out the trans­mis­sion’s giblets they all go to­gether on their re­spec­tive shafts and get an­other crit­i­cal eye­ing-up. Next the gear se­lec­tor forks are in­stalled in the up­per en­gine case ready for the main and layshaft to be lo­cated and checked one fi­nal time. In or­der to

com­plete the en­sem­ble the crack shaft assem­bly is care­fully placed into the up­per case en­sur­ing the var­i­ous lo­cat­ing pegs, dow­els and C-clips are prop­erly homed. There’s been a spate of gear­box bear­ing fail­ures within the Kawasaki triples com­mu­nity of late, which ob­vi­ously caused some con­ster­na­tion. It turns out folk had been buy­ing the cor­rect spec­i­fi­ca­tion bear­ings re­plete with the ap­pro­pri­ate lo­cat­ing groove. How­ever, it turns out the groove wasn’t in the cor­rect place, it was frac­tion­ally out but still al­lowed the case to be as­sem­bled – such fun! The up­per en­gine case, which was po­si­tioned up­side down, is also rest­ing on some strate­gi­cally placed wooden blocks. Th­ese al­low the three con­rods to hang free in the breeze so there’s no like­li­hood of them get­ting dam­aged when the lower en­gine case gets tapped into place. Think­ing ahead can save time, tem­per and money! The lower crank­case is in­stalled over the nu­mer­ous studs and onto a joint that’s al­ready care­fully been treated with an ap­pro­pri­ate sealer. The var­i­ous nuts and wash­ers are added, tight­ened and torqued down in se­quence, so we grab a brew and smile that self-sat­is­fied grin and a job well done. At least un­til we go back for a fi­nal san­ity check to find that there’s an is­sue se­lect­ing gears. A small yet per­fectly formed cloud of pro­fan­i­ties gath­ers over the work­shop! A long story cut short it fi­nally turns out that one of the se­lec­tor forks has the tini­est of bends in it. It wasn’t some­thing spot­ted dur­ing the var­i­ous in­spec­tion stages, nor was there any ev­i­dence of the blu­ing or over­heat­ing you oc­ca­sion­ally see on the ends of the fork’s fin­gers. Dis­as­ter is averted with an­other se­lec­tor fork taken from stock and

the er­rant one lobbed into the waste bin where it’ll never waste any­one else’s time ever again. Fi­nally, the last job on the en­gine is to fit the gear se­lec­tor shaft, pri­mary gears and the clutch bas­ket. The plates and springs will stay in their re­spec­tive bags un­til we progress be­yond the next part of the build. This in­volves get­ting arch stro­ker fan Rob Pem­ber­ton of SPA Mo­tor­cy­cles to check deck heights and ma­chine/ad­just ac­cord­ingly, bore the bar­rels to suit new pis­tons yet to be ac­quired (more bloody ex­pense) and sub­tly port the en­gine. In re­al­ity what Rob will be do­ing is to re­move any bar­rel-to-bar­rel vari­a­tions or dis­crep­an­cies and mov­ing the flow dy­nam­ics just be­yond blue print­ing. He’ll also be re­work­ing the Kawasaki cylin­der and re­mov­ing their clas­sic ‘top-hat’ com­bus­tion cham­bers. The man has done a huge amount of work on stro­ker heads and, cru­cially, gets the best out of the en­gines with what passes for petrol th­ese days. Even more im­por­tantly, Rob’s prag­matic ap­proach to stro­ker fet­tling means he adds to the re­li­a­bil­ity side of the equa­tion, rather de­nud­ing it. His work on my Yamaha RD350 has al­ready made me a firm fan. Else­where and away from the en­gine, progress has been made on the chas­sis side of things. We now have a rolling chas­sis and I have to say it looks good and espe­cially so when you con­sider that the orig­i­nal KH250 wasn’t far off a canal find. Yes, there’s ev­i­dence of rust pits here and there, but most will be cov­ered with pan­els any­way. The front-end looks im­pres­sive and Ian’s had the disc very gen­tly blasted to re­move all the cor­ro­sion. It’ll need a gen­tle hand on the brake lever at first but it will soon smooth down. Han­dle­bars are a Net­ley Marsh au­to­jum­ble buy and are sup­pos­edly for a Norton, more heresy! The clock and head­lamp brack­ets look the busi­ness in satin black and now house some very tidy used clocks that Ian has do­nated to the cause… an­other spares bin raided then! If you study our open­ing shot care­fully you’ll see the KH250 chain guard my lo­cal met­al­smith Iain Cameron mod­i­fied for me. It now has those char­ac­ter­is­tic pressed out holes that were a fea­ture of the ear­li­est triples. Call me a diva if you like but I reckon they set off the rear end of the bike nicely, as do the re­mote reser­voir rear shocks, so it’s a damn shame the left-hand one fouls that chain guard! It’s so far out it’s im­pos­si­ble to bolt it in at the bot­tom with­out bend­ing the chain guard. There’s noth­ing for it but to look again for an­other set of alternative shocks that will fit, but that’s the only back­wards step so far with this cur­rent fet­tling ses­sion. To end on a pos­i­tive note, the ex­change seat has re­turned back from Phil Turner at P&K Clas­sic Bikes. As hoped the orig­i­nal foam was in good con­di­tion so it was reused. The base now sports some fresh black pow­der coat­ing and the pre­vi­ously ripped KH cover has gone to be re­placed with new vinyl that runs the same em­boss­ing as used on the first S2 triples – one more sub­tle nu­ance that cries back to the early, manic triples. So that leaves the paint kit to be sorted, the en­gine to get to Chel­tenham and some new pis­tons to buy, plus the wiring. Old bikes aren’t cheap any­more and I’m be­gin­ning to won­der if they ever really were!

Thanks this month to

P&K Mo­tor­cy­cles, SPA Mo­tor­cy­cles, Kawa Triple parts.

The cases have come to­gether at last!

Gear train apart...

...and now sorted.

Bot­tom end/gears in...

...gear train comes to­gether.

Scoop loves it when...

...beau­ti­ful parts seem to fit...

...like magic!

Phil at P&K does the busi­ness...

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