Project Moto3 .................................
The end’s not yet in sight, but progress has been made this month.
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!
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.