Project Moto3 .................................

The end’s not yet in sight, but progress has been made this month.

Fast Bikes - - CONTENTS -

W e’re get­ting there. One bit at a time (lit­er­ally), but the Moto3 bike’s build is slowly start­ing to pick up pace. If you’re up-to-date with our tale of woe so far then you’ll know we’ve had more co­nun­drums than a fat kid in a sweet shop, but we’ve made some bold de­ci­sions and the re­sults are pay­ing off. We went on a bit of a wild goose chase with the yokes, but since de­cid­ing to set­tle with the stock GSX-R600 units, a lot of the po­ten­tial prob­lems have dis­ap­peared; such as wheel spac­ing. That was prov­ing a right nightmare, ow­ing to the fact that the Gixer forks’ ra­di­ally mounted caliper was de­ter­min­ing the dis­tance per­mis­si­ble be­tween the fork legs and the wheel’s spokes.

Any­way, with­out wish­ing to sound like a par­rot and go over it all again, we fig­ured out our best path and I’m pleased to an­nounce that we now have a func­tion­ing spin­dle (com­plete with spac­ers) ma­chined and look­ing dap­per. Hooray! Clive, who’s been the brains be­hind this build, did all the work­ings out and came up with a de­sign that saw a boss, with an in­ter­nally tapped thread, ma­chined into the far side fork leg bot­tom, into which the threaded end of our spin­dle could lo­cate. It cracked me up when I saw how he’d drawn it on some old scrap of paper, but it did the trick and the unit works a treat – so much for CAD and all that.

The other big bit of news this month is that we’ve got a new steer­ing stem pin. Be­cause the GSX-R600 stem was too short to be utilised on the RM-Z’s frame (and the RM-Z’s stem was a mil­lion miles out from fit­ting the GSX-R’s yokes), we were left with no choice than to draw up an­other de­sign and get the de­sired unit pro­duced from scratch. Clive’s mate stepped in to lend a hand with this lit­tle num­ber, and the end re­sult is we’ve now got a stem that meets the cri­te­ria a treat. It’s per­fect, just like the new steer­ing head bear­ings we fit­ted into place be­fore as­sem­bling the yokes and stem bolt into their new home.

You’re prob­a­bly won­der­ing why I’m get­ting so ex­cited about such sim­ple progress, but for a mo­tor­cy­cle that’s need­ing so much tweak­ing and mod­i­fy­ing, the pro­cure­ment of these key parts is huge news. They’ve been blight­ing the build from day one, like a po­lice­man’s pres­ence at a co­caine party. But we’re over that now and things are look­ing up. The front wheel is in and looks rather dap­per in its new home, de­spite the fact the front tyre’s

balder than Wayne Rooney – pre-op. New tyres are very much needed, es­pe­cially as we’ve now found a 3.5in rear rim to suit the build. The front’s a 3in item, which we’re hop­ing to run a 100-pro­file tyre on. At the rear, the 3.5in rim should take a 120-pro­file hoop. I’m guess­ing at sizes right now, but I’ve fired a few emails to much more knowl­edge­able peo­ple than I to work out what the best op­tions are go­ing to be. In the­ory, we want to be run­ning the small­est tyres pos­si­ble, as it’ll help this baby turn sharper. Not that we’re ex­pect­ing it to be a pig, with its feath­er­weight mass and 1300mm wheel­base. Or at least it bet­ter not be!

While the front wheel’s fit­ting a treat, the off­set of the Aprilia RS125’s domed brake disc ro­tor isn’t suf­fi­cient enough to slot ex­actly cen­tral in the caliper. This means were hav­ing to get the drill out and bore holes on the op­po­site (and prouder) side of the rim, which we’ll tap so we mount the disc to it. It’s not a big job, but it’s ex­tra work that we could have done with­out. At the rear of the bike, the new rim looks spot on for our de­sired di­men­sions. The has­sle is the RM-Z’s stock caliper, which is sim­ply too big. We’re go­ing to have to find a donor off a scooter, or some­thing small: if you’ve got any sug­ges­tions, we’re all ears.

As with the front wheel, the rear wheel’s stan­dard bear­ings are go­ing to be re­placed for the largest units we can fit. We’ve ended up with a 17mm spin­dle up the front, and hope­fully we’ll be able to mir­ror that at the back. Be­cause the rear swingarm’s already slot­ted for a larger di­am­e­ter spin­dle, Clive came up with a top-hat de­sign that will act as a spacer to adapt the bore to suit our needs. As soon as we know what size spin­dle we’re go­ing with, we’ll just drill the cen­tres of the top-hats to suit. Sim­ples. But that’s a job for next month, along with a whole host of other bits. Now we can crack on with a whole host of jobs, so the bike should start look­ing more fin­ished soon. It’s been one hell of a ride, but we’re chuffed with how things are go­ing. No one ever said this was go­ing to be easy, but I know it will be worth it.

We’re not break­ing out the cham­pers just yet...

The disc needs to run dead cen­tre in the caliper.

Ready for some rub­ber!

Easy, right?

It fits! Thank fork for that!

Next on the agenda: chain align­ment. Gold medal dis­cus! A tapped in­sert means the spin­dle screws in the fork bot­tom. With the new stem in place, the yokes bolt to­gether a treat. The spin­dle’s milled from solid. Ready for the scrap pile. Clive couldn’t con­tain his ex­cite­ment.

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