Mr B’s Project Drag Bike
The Accidental Drag Bike
This bike was planned to be a road legal lowrider, but having dry built it over a year or so, I finally pushed it outside, where I could stand back and admire it.. erm… except I didn’t like what I saw… too much rake, not enough stretch.. not good. Soon after, a mate bought the frame, forks and wheels, which left me with a 120 cubic inch (2000cc) Merch Evo style motor and a six speed gearbox. They sat in the garage for another year while other projects filled my time and emptied my wallet. Eventually, a local bike engineering shop, RRACE, convinced me it would be a good idea to go drag racing. They had a spare Daytec frame, I had a big inch motor that would do the job, so a deal was done. I swapped a tuned XL1200 Sporty for the frame, and all the parts and labour to build up a complete rolling chassis. Using the forks, wheels and brakes, from a ZXR12, and lots of 1-off machined parts, the plan was to build a compact, lightweight machine that would be competitive in the NAST Supertwins race series. Where it would be racing against tuned V-Rods, TL1000s, Aprilia RSVs and so on.
See www.supertwins.co.uk for more details.
It was always going to be quick for a ‘Harley’, but it also had to look good. I was trying for a cut down, light, slightly retro feel, but still recognisable as a ‘Harley’- a Bobber in fact. But not some copy of a style from half a century ago, no, this bobber used modern parts and technology, hence its new nickname the ‘21st century bobber’. Some elements have been blatantly copied from Mark Van Dr Kwak’s famous Shovelhead, as found on his equally famous website www.DBBP.Com.
Machining and Fabrication
It took about 18 months before we had a running bike, mainly because I had to spend a year working abroad, which slowed things down. Jeff Hill at RRACE spent many happy hours making the small, but vital one-off parts I had designed. That is, I drew out the part, showed it to Jeff, who told me why it couldn’t work, then he went off and made a much better version. A casual observer looking over the bike wouldn’t see much to shout about, but there’s a hell of a lot of thought and labour gone into making the bike strong enough to cope with the drag strip, and getting the right ‘look’. Here are some examples of the time and effort that goes into the build….
The Swing Arm & Jockey Wheel
The elegant but heavy Daytec swing-arm was replaced with a braced JMC alloy jobby, found gathering dust in another mates garage. This required a fair bit of work to fit, along with the need for a jockey wheel to allow the chain to clear the arm’s under brace. This contraption cost a hundred quid from Germany, and consisted of a 50p skateboard wheel, a spring and a few pieces of cheap steel plate. It didn’t fit. Load of crap. In the end the only thing used was the skateboard wheel; everything else had to be fabricated from scratch.
Steering Damper
I had a lovely LSL damper kit from V&M Racing, which had been destined for my old Vmax, but for various reasons it had never been fitted. I’d been itching to find a use for it for ages, and now was my chance. A 46 mm fork clamp came from Demon Tweaks for £18, but fitting the damper to the frame took a lot more effort, as I didn’t just want a crude tab welding to the down tube. A mounting bracket was milled from chunk of billet alloy, which in turn was bolted to the fame via a couple of threaded lugs welded to down tube. These are hidden from view by the bracket. Very neat and very expensive.
Fuel Tank
The Sportster peanut tank is another cast off. To fit it to the softail frame, first the original mounts had to be cut off the backbone (I did this bit by hand – took two bloody hours!). Next, four steel cups were turned up on the lathe which were welded into the underside of the tank. These cups are threaded to take four rubber tank bungs, which then fit snugly inside the cups, hence they are ‘invisible’. Finally, a couple of sturdy mounting brackets were made to bolt the tank to the frame, which were cross drilled for lightness, and cos it looked good.
A new and bigger breather pipe was set into the tank top, as the original wouldn’t be big enough when the motors running flat out with nitrous, oh, forgot to mention its got NOS as well.. Next something a bit different for the filler cap. Everyone said it should have a aero style flush filler – very racy. But no, I wanted something with a bit more retro ‘bobber’ character. After a call to John Williams at the Tank Shop up in Dumfries, and even more milling and welding, that’s what I got. Common enough on 70’s Italian superbikes, but I’ve never seen a Monza cap on a Harley before.
Rear Fender x 3
I got myself into a right mess with this. Tried to be a bit too clever, by using a MV Agusta F4 tail section, it could be made to fit ok, and the length was spot on. But I didn’t realise how wide the thing was, and it looked ridiculous with the slim XL tank. Second try was a cut down conventional fender. This one looked ok, but was a touch too narrow. So Jeff split and widened it by an inch, and while he had the welder fired up, he also added a bead along the edge, just like on Discovery channel. Was I happy now? Nope. Still wasn’t quite right. Finally, I bought yet another fender, this is mounted via a couple of composite alloy side plates, which took more hours of milling.
5th Gearbox Mount
When a wider wheel is fitted to an Evo softail, the gearbox has to be moved over to the right, so the drive belt or chain clears the rear tyre. This move is achieved by simply bolting the gearbox to an aftermarket mounting plate, which has its four mounting holes drilled the required amount to the right. So far, so easy. But the gearbox has a fifth mounting stud over on its left side. This stud normally bolts to a bracket welded to the lower frame rail. With the gearbox moved to the right, this fifth mounting stud has nowhere to go, and is usually cut off as it interferes with the rear shock which sits directly beneath the gearbox. Losing the fifth mounting point isn’t a problem on a standard Harley, as the box is still firmly held in place by the four remaining studs and the inner primary chain case. But with four times the power of a standard big twin, something had to be done to keep the box from going awol. So a Delkron inner primary was fitted, and a replacement 5th mount fabricated. I’ve seen a few different brackets used to replace the 5th mount; they all looked a bit whimpy to me, more for show than go. Therefore something a lot more substantial was machined from high grade alloy, again it doesn’t look that special, but a lot of work went into getting it right. It looks like a high tech horseshoe cradling the lower half of the box. You can see it immediately behind the exhaust outlet in the picture below. Also on view is the 1-off stainless exhaust system, rearsets, catch tank, designed by me, and all made by Jeff Hill. Also note the twin outlet fuel tap, one to the carb, and one to the fuel pump for the NOS system.
The Rule Book
The ACU technical manual has been downloaded and carefully studied. All was going to plan until I found out that the series, in which I intended to race, had changed the rules for 2007. Now I didn’t need lights (good), but I did need a front fender (bad), since the forks have been shaved. Just means the front end will have to come apart yet again, to have a bit of plastic fixed to the underside of the fork brace. Bikes also need an ignition cut-out, attached to a lanyard around the riders’ wrist. So if you fall off, at least the motor dies, even if you don’t. It also needs an engine breather catch tank, of at least 550ml. An odd size, till I realised it’s a pint in old money. Having worked out where all this stuff was going to go, my lovely simple bike is starting to get a bit cluttered. Its been a squeeze to find space for the electrics and the nitrous system..
The Last Tricky Bits
The last tricky bit was to make the linkage from the rearset gearlever to the gearbox. Not easy as the oil tank and primary cover are in the way. To make matters more complicated it had to have a reversed change pattern and an airshifter. The latter is a simple air powered ram, activated by a button next to the clutch lever. The idea is that you change gear with the bar mounted button, while keeping the throttle wide open. A small electronic black box disables the spark to the motor for a split second, to unload the gears and allow the next cog to the selected. Well that’s the theory, cant say I’m looking forward to trying it out for the first time. Below is an old photo showing the left hand side of the bike, we’ve since changed the colour (to Ducati red), modified the gearchange, and lots more ....
Above..catch tank (upright), and pressure tank for air shifter (horizontal). Also the stainless 2-1 exhaust (no baffles..its a bit loud), S&S Super G carb, steering damper and oil cooler. This was taken before the NOS system was installed.
Putting a Softtail on a Diet
I mentioned that getting the bike as light as possible was a big priority, with a target of 500 lbs or less, ready to run. This compares to 682 lbs wet (654 lbs dry) for a 2007 softtail standard. Dry is without any fluids; fuel, oil, brake fluid, even battery acid. When the bike had to be hoisted off its workbench, the wheels were gently lowered onto the bathroom scales I’d brought along. The readings were 107 (rear) + 85 (front) = 192kg. Or 423 lbs. not bad at all, though it still has to have a few electrical bits and bobs fitted. So I reckon it’ll run out at about 470lbs wet.
Back in Black?
Under the workshop lights the black bodywork looked suitably mean, but on the day it was finally rolled out into the winter light, it just looked dull and boring. While it was off at SpodMoto of Warrington www.spodmoto.co.uk having its electrickery and NOS installed, the tank and rear fender were taken away for fresh paint. It didn’t need a super trick paintjob, since everyone told me race bikes attract scratches and chips as they’re man handled into vans, trailers and workshops. If black was no use, then it would have to be red, something similar to my 131 road bike. A new paint shop had opened its doors this year, just a couple of miles away from me, so I decided to give them a go. Check them out at www.graphicaairbrush.co.uk The new paint has been done at below cost, as a rolling advert. The only problem I’ve had is convincing them not to go overboard with an intricate design. It has ended up a bit more intricate than I had in mind, but not as much as they would like.. so I guess we’ll call it a draw. It’s now painted with a Ducati red base, gold details, with a pearl over the top, even the ‘decals’ aren’t stuck on, they’re painted. They also did my old Simpson lid to match.
One big problem was how to get the motor run in. Its not road legal, yet the big motor really needs at least a thousand miles before it can be run in anger. The expensive solution was to stick it on a rolling road dyno for 500 ‘miles’. So now the carb and ignition are set just right, and a few niggling problems have come to light. These are best found now, then on the racetrack. It got so hot, that the paint on the oil tank blistered. We didn’t redline the motor or use the NOS on the dyno, but it still put down 115bhp at the rear wheel, with a flat torque curve, starting at over 100 lb/ft at 2000 rpm, peaking at 124 lb/ft at 5000 rpm. We should get a bit more when it’s fully run in, and I can take it to 6000 rpm. Then the NOS system will give an additional 60 bhp to start with.
The first outing will be at Santa Pod, on er.. Friday 13th June. Just hope I’m not crap at this drag racing lark.
Mister B.
UPDATE:
The Saturday we had to go thru scrutineering.. Got thru that ok.. Then I had to do 3 'observed runs' … the first was just a burnout, and go up to the lights correctly..pre-stage, stage, and go. Then bimble up the track at 40mph… The second was the same, but this time I was allowed to do a quick run but only up to 1/8 mile.. Then I had to back off.. The last run of the day.. we were the very last one to go in the day.. My first a full power run.. we did ok, so were allowed to compete on the Sunday.. The only problem we had was just the rev counter not working.. Maybe cos I crashed it on the Friday evening.. When I was showing off to Tim's dad (Tim was my crew for the weekend..couldnt have done it without him.. He is a partner at SPODMOTO in Warrington, who did a lot of work on the bike), in his dads farmyard..the bike suffered a couple of bent levers.. Soon sorted.. Farms have a decent workshop.. While I was patched up by his mum.. Was only wearing jeans and t-shirt.. Took the skin of the back of me hand and shoulder..it bloody hurt.. Then during the weekend, putting on my right hand glove (and taking it off again) was pretty painfull.
Still we were thru to out first race.. Against a CX 650 turbo café racer.. Which we won… except I has disqualified due to a small error by my mate.. 'The Crew'.. He forgot to close my visor after the burn out.. I couldn’t do it.. And when he finally realised, he reached over and snapped it shut.. But too late, I already had the front wheel on the 'Blue line'.. After which he aint allowed to touch me… oh well, meant I could relax and chill out at last…
