My new Project.. From Chop to...
Discussion
With my Norley Café racer completed at last, its time to start a new project, I must be mad..
I had an unfinished Evo chop sat in the corner of the garage gathering dust, so decided to do something with it. Problem is I didn't want a hard tailed chop, that's probably the reason its sat unloved for a couple of years. But I did want to build another drag bike. I never got the best out of the last one, now I had the chance to build something better using the parts I had without throwing too much money at it.
What I had was a heavy (but strong) rigid frame with 4 inch stretch, with a 127cubic inch Evo motor (140bhp), a belt primary, 6 speed aftermarket gearbox and 'performance' clutch.
What I needed was a different frame, lightweight wheels and forks and a few bits and bobs..chain, brake lines, tyres etc. One good thing is that when I sold my last drag bike, all the parts specific to racing that were removed, came back to me as part of the deal. That includes the air shifter, foot controls, bodywork and exhaust, it all helps.
To save money and time, maybe I could modify the frame I had, rather than commission a new one? I'd rather get something running sooner and evolve it, than try to build something perfect but take years to do it.
I got my tape measure out and measured the frame dimensions, then put it down on paper. Its not mm perfect, but not too far out.
I had an unfinished Evo chop sat in the corner of the garage gathering dust, so decided to do something with it. Problem is I didn't want a hard tailed chop, that's probably the reason its sat unloved for a couple of years. But I did want to build another drag bike. I never got the best out of the last one, now I had the chance to build something better using the parts I had without throwing too much money at it.
What I had was a heavy (but strong) rigid frame with 4 inch stretch, with a 127cubic inch Evo motor (140bhp), a belt primary, 6 speed aftermarket gearbox and 'performance' clutch.
What I needed was a different frame, lightweight wheels and forks and a few bits and bobs..chain, brake lines, tyres etc. One good thing is that when I sold my last drag bike, all the parts specific to racing that were removed, came back to me as part of the deal. That includes the air shifter, foot controls, bodywork and exhaust, it all helps.
To save money and time, maybe I could modify the frame I had, rather than commission a new one? I'd rather get something running sooner and evolve it, than try to build something perfect but take years to do it.
I got my tape measure out and measured the frame dimensions, then put it down on paper. Its not mm perfect, but not too far out.
If the head stock, top tube and down tubes were cut away, the front end of the frame could be lowered, lengthened, raked and braced to give me a cheap frame to go racing with. A new light weight frame in Chrome moly would cost over a grand, while modding the frame I had would be only £250. The budget for this bike is tiny, I want to get it running as cheap as possible, so a new lightweight frame will have to wait.
First task was to remove the heavy steel rear mudguard, and replace it with a fibreglass one I'd had in the shed for ages. Its a spare for the one fitted to my road bike, made by the German company HPU. Spotted it on Ebay for £30. Still needs mounting of course, already looks much better..
The next issue was the wheels and forks. Ideally I wanted to fit a pair of super light sports bike wheels, 6 inch on the back, with a light slender set of forks. The forks from an XL would do nicely, 39 mm, narrow glide, with the steering stem that'll fit straight into the headstock with no bother.
Well, I had a pair of XL fork legs in the shed, however the chrome was a little pitted, not where it mattered, but still couldn't fit them as they were. Options would be to get the stanchions rechromed for around £135,or buy new stanchions for a few quid more. Either way that's more than I wanted to pay. I'll keep looking for a front end off a middleweight Jap sports bike. I can always change the stem to suite HD head bearings if needed.
As for wheels, my first port of call is to my mate Jeff, he's always got a few bits and bobs in his workshop attic. No 17inch sports bike wheels, but he did have one of his homemade split rim wheels. 17 inches, compomotive rims, just over 6 inches wide. Just the job.. except it was a bit on the heavy side. It will fit the frame with a bit of machining, and it'll need new bearings or top hat spacers to fit the 3/4 inch rear spindle. The clincher was that I did a swap so it didn't cost me any cash. I took it home.
The next issue was the wheels and forks. Ideally I wanted to fit a pair of super light sports bike wheels, 6 inch on the back, with a light slender set of forks. The forks from an XL would do nicely, 39 mm, narrow glide, with the steering stem that'll fit straight into the headstock with no bother.
Well, I had a pair of XL fork legs in the shed, however the chrome was a little pitted, not where it mattered, but still couldn't fit them as they were. Options would be to get the stanchions rechromed for around £135,or buy new stanchions for a few quid more. Either way that's more than I wanted to pay. I'll keep looking for a front end off a middleweight Jap sports bike. I can always change the stem to suite HD head bearings if needed.
As for wheels, my first port of call is to my mate Jeff, he's always got a few bits and bobs in his workshop attic. No 17inch sports bike wheels, but he did have one of his homemade split rim wheels. 17 inches, compomotive rims, just over 6 inches wide. Just the job.. except it was a bit on the heavy side. It will fit the frame with a bit of machining, and it'll need new bearings or top hat spacers to fit the 3/4 inch rear spindle. The clincher was that I did a swap so it didn't cost me any cash. I took it home.
I had my local bike shop fit an old tyre from their scrap pile, didn't cost anything, and it'll only be used for setting up. First problem is that the split rim wheel leaks like a sieve, it will need much better sealing before its used. Second issue is that the hubs will need to be shortened to make room for a caliper mount, not really a problem, just more work. The third problem is that my rear mudguard (which I really like the look of) is a few mm too narrow. I'll have to widen it some how.
I started work on the bike last month, I booked the frame in to be modified with CCD down in Norfolk in Sept (I took it there yesterday). Which gave me a month or so to work on the bike before I had to dismantle everything to take the frame to CCD. I asked around fro advice on widening the fibreglass seat unit, bought some resin, matting and 5m of Roven tape (similar to matting but much neater to use).
Step one was to cut the unit in half length ways, and use a couple of temporary brackets to position the two halves an inch or so apart.
Step one was to cut the unit in half length ways, and use a couple of temporary brackets to position the two halves an inch or so apart.
With the fibre glassing out of the way, I could do a few easier jobs. First I made a new mount for the air shifter ram. This is a ram which uses compressed air to allow clutchless gear changes at full revs using a button on the bars. When you hit the button, a switch cuts power to the coils for a fraction of second as the air ram changes gear. The compressed air is held in small cylinder and needs to be refilled with a hand pump before every race to around 150psi. The air shifter only works one way, so I'll add a small hand lever to let me change down after the run. 
The gearbox comes with a pulley fitted out of the box, but I'll be using chain not belt final drive, so I took the gearbox to my local bike shop where they kindly removed the pulley nut for me, so Icould fit a sprocket I had left over from my last drag bike. To remove the pulley nut, it needs a very deep socket, which I don't have. I didn't ask them to torque down the nut yet, as it may need a small spacer behind it to get the chain alignment right.
Back to the rear wheel. The hubs were removed to narrow them enough to make room for a caliper bracket, and also to lose some weight. That done, I now needed a caliper. A lightweight Brembo would do nicely, but there most be a lot optimists on Ebay as they wanted far too much for a used caliper, I ended up buying a new one for £80.
Coming up to date, I'd given myself a headache by using a one off billet rear wheel, I now needed a matching front wheel. The hubs and centres could be made, its the rims that are the tricky part. Suitable split rims aren't easy to find, and if you do find any, they aren't cheap.
But I had a cunning plan, involving the sacrifice of one of these.. a 17 inch gold Astralite that had seen better days, which came off a mates old Z1 drag bike. New Astralites are being made again such is the demand, and go for over a thousand quid a pair. I was reluctant to destroy mine, but needs must.
But I had a cunning plan, involving the sacrifice of one of these.. a 17 inch gold Astralite that had seen better days, which came off a mates old Z1 drag bike. New Astralites are being made again such is the demand, and go for over a thousand quid a pair. I was reluctant to destroy mine, but needs must.
The wheel consists of two sides which are riveted together at the rim, with an alloy hub sandwiched in the centre. We drilled out each of rivets, separated the two halves, then cut the outer rim section from the wheel halves.
Next we machined a new billet centre (the spokes), which was drilled with 80 blind holes (40 each side) to match the rivet holes in the rims. Usually with split rim wheels, the rims and centres are drilled and held together with bolts and nuts. But my mate Jeff insists on doing it his way. The holes in the rims are bevelled to take countersunk socket head bolts, while the billet centres aren't drilled to take a nut and bolt, but drilled and tapped by hand. This means there are no nuts needed, all you see if 40 countersunk socket heads on each side of the wheel.
This is a work in progress pic of the new wheel. The centre spokes need to machined to match the rear wheel. and reduce the weight a little
Next we machined a new billet centre (the spokes), which was drilled with 80 blind holes (40 each side) to match the rivet holes in the rims. Usually with split rim wheels, the rims and centres are drilled and held together with bolts and nuts. But my mate Jeff insists on doing it his way. The holes in the rims are bevelled to take countersunk socket head bolts, while the billet centres aren't drilled to take a nut and bolt, but drilled and tapped by hand. This means there are no nuts needed, all you see if 40 countersunk socket heads on each side of the wheel.
This is a work in progress pic of the new wheel. The centre spokes need to machined to match the rear wheel. and reduce the weight a little
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