BACKWITH A BANG
You might think not much has changed with Bruce’s project, and to a certain extent you’d be right, but the ball’s very much rolling…
H ave you ever watched one of those Grand Designs housing programmes and wondered why the hell they’re bothering? Surely, the easier thing to do is just rock up at an estate agents and take your pick of homes. The only reason I make that reference is because it’s very relatable to my own little project. For £14k(ish) you can buy a base model Moto3 bike from Padgetts that looks the tits and is ready to rock.
And for even less than that you can buy an abundance of track bikes that would smoke my bike’s prospects without a modicum of hesitation. And yet here I am, balls deep in bills, stress and excuses, not a lot further to completing a bike that is little more than a pipe dream. So why bother? I’ve asked myself that question many times so far, but each time I catch a glimpse of this wannabe GP-bike and it makes me feel all warm inside. That’s not because I’ve pissed myself (again), but more owing to the realisation that this bike is morphing into something very special. Admittedly, it’s taking it’s time but that’s the nature of a custom build… as I’m quickly finding out.
You’ve got to be yoking!
So what’s happened since we last caught up? Well, I’ve had a haircut; I went to see the in-laws; my dog got some flea treatment. But enough about my wild lifestyle. As far as the bike goes, a lot, and a little has changed. Confused?
Well, see, there’s not a great deal of visual progress to show off, but like a graceful swan that’s smashing the backdoors out of its paddle limiter sub-surface, we’re really making progress with the Moto3 bike; you just can’t see it. Let me start by updating you on the yokes. As we’ve opted to run some trick looking GSX-R 600 forks, we also thought it wise to use the same model’s yokes. But that bit didn’t work out. While the Gixer runs a 3.5in front rim as standard, our little pocket rocket’s being kitted with a featherweight 2.5in jobbie, that takes the front tyre’s sizing down from a 120-profile to a very modest 90-profile.
Why have we done that? It’s a combination of saving weight and maximising the agility of the bike. The truth is a bike of this size doesn’t need massive wheels, and the unsprung mass we’ve saved by going down this route is huge; we lopped off 1.5kg. But by going down to such a small wheel, we ended up with a rim that was being shouldered by forks so wide apart it looked like they were bolted to some other bike. It just looked crap, with the only solution being to produce some bespoke yokes for the bike. And let me tell you that’s not cheap. They’re being CNC’d out of billet aluminium, with the width being reduced by 10.5mm each side. The end result will mean the forks sit a lot closer to the wheels, which is awesome, but the three weeks it takes to make them is not so awesome. More on those next month.
Wheelie good news
Back to those wheels. Technically, I don’t own them, but my good mate Clive, who’s the real mastermind behind this build, has kindly loaned me this pair of beauties that fit as standard in a Honda RS125. They’re perfect for the stringent Moto3 regs that insist on a 2.5in front rim and a 3.5in rear. Believe me when I say that I looked everywhere for an elusive set of rims meeting those measurements, but it would appear they’re only present on racing motorcycles.
So, if you know of any RS125 rims for sale, drop me a line as I’m after some. But, remember, we’re mates, so best prices and all that. If there was to be any downside to the RS’s rims, it would be their spindly spindles. Like the overly big rims, a bike of this size doesn’t need massive spindles, because it doesn’t have the weight to warrant them, but Clive was a little concerned by the OE 15mm bearings fitted to his wheels, so took the decision to max them out as far as possible. That in its own right cost a bit of time, but he came up trumps with some 17mm diameter bearings, which have now been bashed into place.
It’s only a 2mm gain, but that kind of thing can make a big difference. As for the actual spindles, it obviously means we need to go about making bespoke ones for both the front and rear fixings. That’s no easy job, with the front end being compromised by the 22mm apertures for the standard GSX-R spindles, while the RM-Z’s swingarm has recesses of about the same size. We’ve had to go back to the drawing board, but we think we’ve come up a design that we’ll get machined from a length of solid… again, at the price of both time and money. But we need the wheels and spacers sorting pronto, because without those little gems in place, we ain’t going nowhere.
The only other potential headache is sorting the chain alignment. It’s going to be tighter than a gnat’s chuff, but we’re hoping we can adapt the spacing of the front sprocket to give us more tolerance with the rear sprocket’s alignment. If that’s even slightly long, we’ll end up mullering the power output oil seal’s gasket.
It’s not all bad
Yep, it’s all good fun. But the challenge of a build like this is perversely endearing. You scratch away for answers that are inevitably there; even if they appear annoyingly elusive to start with. But some bits have been much more straightforward to sort, with the braking situation being one of them. We’ve invested in an awesome Frando radial master cylinder, with a 15mm piston.
They’re also available in 17mm and 19mm fitments, but the guys at Venhill, who retail the systems, advised us that bigger isn’t always better. Too much power and our featherweight bike will just endo itself silly. Especially considering we’ve opted for a single GSX-R 600 Tokico caliper up front, with more stopping power on tap than an Armco barrier. And to make the anchorage even more profound, we’ve fitted Venhill braided hoses to the mix.
As this is a custom build, we first had to measure what length of line we needed, before calling through a measurement. As well as doing kits for just about every conceivable model on the market, those guys also offer lines to custom lengths, which meant there was no problem sorting this.
What did present more of a problem was the mahoosive front caliper, which was grinding like R-Kelly all over the front wheel’s spokes. No one needs that in their life, so we opted to create a 6mm aluminium spacer to push the rotor off of the rim. This has proven to be just the ticket. And we’re hopeful that the narrower yokes will have brought the relationship between the radially mounted –fixed position – caliper and the disc rotor into perfect correlation. One thing’s for sure, the gap’s set to be a whole lot narrower than what it was. But if it’s not cock-on, we can always blame the engineer that’s making them. Or just adapt the 6mm disc spacer plus or minus a few millimetres. We’ll figure it. Same goes for the distance of pad coverage on the rotor. It looks like we might need to remove a small amount of metal from the fork mount to get the caliper closer to the disc, to maximise pad coverage of the disc. But it’s too hard to tell right now. Life’s going to be so much easier when we’ve got a few parts back.
What’s next?
Assuming you’ve not fallen asleep and you’ve grasped all of the previous matter, you’ll grasp that we’ve still got a shit load to do. And we haven’t really got started yet, as the distraught looking remains of a motocross bike highlight. But I’ve faith it will all come good, and next month we should be able to show you more visual progress of all we’ve been doing. One thing I’m particularly excited about is the bike’s new bodywork. The missus was less excited when I told her I’d spent over £800 on a TYGA bodykit, but she spends a lot more on her haircuts than me, so it really does all balance out in the wash. If you’re not familiar with TYGA, they’re market leaders in the production of proper trick looking bodywork; both of the road and race variety.
I checked out their website and felt spoilt for choice with the kits on offer, but the one that really got my endorphins going was the NSR300GP kit. It looks awesome, and I’m sure it will look even more awesome once Clive’s had chance to work his magic spraying the bodywork. As with everything, we’re not expecting the fitment to be straightforward and there’s a chance we’ll have to cut the entire fairing in half and remove a section from its centre, because it’s likely to be too wide for our project bike, but we’ll only know when we get hold of them. And when we know, we’ll let you know. So keep tuned.
WE MAY HAVE TO CUT THE ENTIRE FAIRING IN HALF AND REMOVE A BIT FROM THE MIDDLE