Steve Cooper on his 250/500 two-stroke de­mon build.

Classic Motorcycle Mechanics - - CONTENTS - cmm

Ithink I’m on fairly safe ground when I say my cre­den­tials as a Class One Idiot are now im­pec­ca­bly well es­tab­lished. I coun­sel novi­tiates to only work on one bike at a time, (you mean ‘tell be­gin­ners’, Scoop? Ber­tie) ex­hort those who have been restor­ing for don­keys years not buy a bike in boxes, ad­vise any­one who’ll lis­ten to never, un­der any cir­cum­stances, take some­one else’s aban­doned project and avoid the com­plete but dog rough ‘cheap bar­gain’. And yet I have ac­com­plished the fol­low­ing: • Run four projects at the same time. • Pur­chased a Yamaha AS1 in a myr­iad of pieces all stored in a wet cel­lar. • Ac­quired a Suzuki Rick­man project that had got the bet­ter of its pre­vi­ous owner. • Bought a £250 Suzuki Stinger that was a gen­uine hound. So you would have as­sumed that by now I’d have learnt my les­son wouldn’t you? Fools rush in where wise men fear to tread etc. Have I learnt my les­son? Have I hell! I’ve owned var­i­ous brands of bikes over

the years with the no­table ab­sence of a Kawasaki. A Z1 is both too ex­pen­sive and too large for me; I like Z650s but they’re too much like my erst­while Honda CB750F2N; F se­ries trail ma­chines aren’t what I need right now and most of the leg­endary triples are out­side of my fis­cal abil­i­ties. Please un­der­stand, I don’t need an­other bike, project, li­a­bil­ity (delete as ap­pli­ca­ble) yet I do rather want one… and the no­tion of a stro­ker triple ap­peals but with cer­tain caveats. The 750s are ei­ther too ex­pen­sive or un­wieldy for mug­gins ’ere, the 250s have be­come too pricey for what they per­son­ally offer me, the 500s gen­er­ally don’t han­dle well enough for my style of rid­ing and 350/400 itch is com­fort­ably scratched by my Yamaha RD350. All of which rather lim­its the op­tions un­less one takes a left-field ap­proach and gets in­volved with those that take a lat­eral slant on Kawasaki triples own­er­ship. En­ter stage right Ian Bird and the wor­ry­ingly ad­dic­tive hy­brid he loaned CMM for the Au­gust 2017 is­sue. This bike got un­der my skin al­most from the off and the more I rode it the bet­ter I liked it. Some amal­ga­ma­tions of en­gines and frames re­sult in un­happy bed­fel­lows with poor weight dis­tri­bu­tion and du­bi­ous han­dling while others can be down­right dan­ger­ous. Back in the day, Norvins (Nor­ton Dom­i­na­tor frame with a Vin­cent mo­tor) were the sup­posed pin­na­cle of the hy­brid con­cept yet more than a few were se­ri­ously com­pro­mised by dodgy build qual­ity. The leg­endary Tri­ton (Tri­umph mo­tor and afore­men­tioned chas­sis) came in var­i­ous guises and many were not un­like the cu­rate’s egg – both good and bad in parts. Sim­ply put many

as­pi­rant specials builders can hurl an en­gine into a frame it wasn’t built for but it takes a spe­cific kind of ded­i­ca­tion work­ing to an un­am­bigu­ous blue­print if the end re­sult is go­ing to be a vi­able and safe road ma­chine. I know all of Ian’s bikes are well-built so the 250/500 hy­brid was never go­ing to be a ra­bid hound. The fact that he had the parts on hand to build an­other might have been too much of a temp­ta­tion to re­sist and so it proved. Hav­ing ver­bally com­mit­ted to the pro­gramme a mu­tu­ally agree­able date was se­lected and a se­lec­tion of donor parts laid out on a cold con­crete floor. Key to the en­tire project is a frame with a V5C; at­tempt­ing to con­vince one of the DVLA’S finest about the au­then­tic­ity of a non­no­vaed 250 or 400cc frame bear­ing a 500cc mo­tor of un­cer­tain ori­gins was al­ways go­ing to be sev­eral steps too far for both of us. One for the quiet life me, so Ian man­aged to lo­cate a KH250 chas­sis with said doc­u­men­ta­tion. The KH and later S se­ries frames are gen­er­ally recog­nised as the best han­dling of the breed even if they don’t and can’t run the iconic body pan­els of the first S2, a look I per­son­ally love. For­tu­nately even though Project Hy­brid is obliged to run KH pan­els there’s no rea­son why it shouldn’t ape the ear­lier triple’s looks. As one of these shots shows, we have pretty much ev­ery­thing we need to get un­der way but be­fore we get se­ri­ous the frame needs to be, ahem… gen­tly mod­i­fied. Against all hope and ex­pec­ta­tion the 500cc H1 mo­tor will fit in the phys­i­cally smaller 25/400 frame but there are four sets of brack­ets that need to be ei­ther re­moved, re­lo­cated, re­fab­ri­cated and/or moved. Noth­ing short of a brutish as­sault with a disc cut­ter will ap­par­ently suf­fice but once the old fit­tings are dis­pensed with the half litre mill fits in rather well. In fact the tubes and en­gine look made for each other. Okay yes it all looks a bit snug but there’s a key bonus here that might be eas­ily over­looked. The 500 mo­tor’s new en­forced lo­ca­tion puts more weight over the front wheel which in half litre triple world of­fers a sig­nif­i­cant and sub­stan­tial ad­van­tage – the han­dling is dra­mat­i­cally changed for the bet­ter. Gli­bly ‘all’ that needs to be done from here is to fab­ri­cate a new set of en­gine/gear­box mounts and weld them in place while en­sur­ing the chain lines up. Which is a piece of cake… for some­one else! As we’re us­ing KH run­ning gear ev­ery­thing ought to line up nicely given the in­ter­change­abil­ity be­tween the late S se­ries and the KH250/400S but of course con­di­tion and avail­abil­ity are now key is­sues. We have the req­ui­site num­ber of parts but as yet they’ve only had a cur­sory once over and the lower cor­ner of the tank car­ries a wor­ry­ing amount of filler. The fork stan­chions will need fresh chrome but at least the mud­guards are sound even if they’re not in their first flush of youth; a bit like me to be hon­est. Bet­ter still, a de­cent seat base has been ac­quired which looks as though it was a dealer war­ranty swap out. Bear­ing an au­to­jum­ble price of just £8 it must have been sold decades ago; any­one sell­ing com­plete gen­uine seats for less than a ten­ner a pop would get killed in the stam­pede these days. So we have a set of cases and bar­rels to play around with and for­tu­nately the gear train and crank have been re­moved which fa­cil­i­tates a sig­nif­i­cant im­prove­ment in terms of ma­noeu­vra­bil­ity. With the mo­tor al­ready in pieces it’d be an act of supreme folly not to go through ev­ery­thing with a fine toothed comb. The crank in par­tic­u­lar looks and feels like it has seen bet­ter days so that’s go­ing to be the first big job and doubt­less ex­pense. No one said build­ing a special was go­ing to be cheap or easy!


This is the dream and kinda what Scoop is aim­ing for!

And this is the cur­rent re­al­ity: like a Tamiya kit, but big­ger!

Clas­sic clocks have been found.

One bar­gain seat...

Ev­i­dence on the tank of some dodgy re­pairs: filler ev­ery­where!

The donor mo­tor will need a good clean-up.

Frame brack­ets are at the heart of the trans­plant. Some re­moved, and re-sited but the mo­tor fits well and puts more weight over the front.

Tin­ware for the project looks good.

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