My CN250 Helix

The Front Mudguard

I've managed to convince myself that the Helix needs a front mudguard. Not for weather protection but to smooth the airflow round the front wheel. When I fitted the Pirellis, the crosswind behaviour at speed changed subtly. Instead of a slowish roll from side to side it became more of a quick dart. Now this may have been due to the changed tyre profile, but the Pirellis have a simple deep tread pattern more like current superbike tyres, and I've convinced myself that this is stirring up the air more off the top side of the tyre. Given that the bodywork doesn't extend down enough to shroud the wheel at all and there's no standard mudguard, the top of the wheel (at double road speed) is probably not helping top speed or stability.

Anyway. Over the weekend I bought a Honda CBR600 F1 (jellymould model) front mudguard. This is virtually the same as the CBR1000 of the same era. A bit of inspired bodging with a hacksaw, sureform, drill and a tap has got this mounted using the same mounting points as the little suspension covers. I had to drill and tap the tabs that secure the front of the covers so it's held securely at 4 points. I've also cut off the top and back of the mudguard so there's tyre clearance at full bump. A quick spray with matt black and it almost looks stock. The Helix now has a "beak" below the front bodywork with some vaguely streamlined sides to push the air round the bodywork.

Of course today it's dead calm so it's not a real test, but the bike feels a little more stable at speed and has picked up 1mph on top end[1] I'll have to wait for the more normal UK summer weather of rain and gales for a full test. Later. We had a nice windy day, and I can report that the bike is significantly more stable in sidewinds than before. Looks like a solid win.

[1] This is completely imaginary, of course!

The patent rotating top box/backrest

For this one you need to start with the "tall" pillion backrest. I know some Helix don't have this and I have a sneaking suspicion that the majority of US Helix have the short one.

Anyway, take one dirt cheap Rickman top box. These things are big enough to hold a full face helmet and only cost about £30. They're made from thick black polythene and last forever. You'll find them on the back of most London dispatch bikes. Now if you tilt it forwards so that the lower bottom edge is now on the pillion seat and the base is now hard against the pillion bum stop, it makes a perfect rider's backrest.

If you remove the padding piece from the actual pillion backrest, there are 4 screw holes that can be used for some long bolts that attach the top box through it's base. It's a matter of an hour to get to this point if you're fairly careful about drilling the top box base. Now for the clever bit. The pillion backrest actually swivels on it's mounting point and has two short bars that go forwards and pick up the inside of the pillion handholds. Drill out the bolt holes all the way through the handholds and tap the mounting points on the backrest. You can now bolt a pair of allen head screws from the outside, through the handholds and into the backrest mounts. It's now the work of minutes to whip out the bolts and "voila" the whole top box tilts back to allow room for a pillion and provide a taller backrest for them.

So what I end up with is a comfortable backrest for me, extra space to take a rucksack with a laptop in it and business papers along with some sensible shoes. At the office, the laptop comes out, the M/C boots and helmet go in the top box and the jacket goes in the normal Helix trunk. A quick cigarette and a brush of the hair in the mirror and I can transform myself from greasy biker to City gent in 5 minutes.

The last addition in this area is a secondary brake light. I picked up one of those cheap brake lights designed for the back window of a car and mounted it on the top of the top box right in a car driver's line of vision. The wire runs down the left side, into a hole and down to the rear light connector just forwards of the air cleaner.

By the way, if you ride a Helix and have never had a back rest, it transforms the bike. No longer will you hang off the bars like a monkey suffering back pain but now be able to recline in comfort and smile sweetly at your fellow kings of the road.

Screen, Handlebars and stuff

The Helix as standard has a problem with airflow round and over the screen. At WFO, there's really a lot of turbulence that hits your helmet and makes it bobble around. Sometimes it's enough to blur your vision. So here's what I did.

The first problem is the handlebars are too far forwards, especially with the topbox/backrest. In the bottom of the toolbox I had some handlebar raisers. These are C pieces that go under the clamps and raise the handlebar about 1/2". Then I tilted them back about 10-15 deg. This brings my arms at a comfortable stretch (I should add here that I'm 5'8") so my fore arms are about horizontal. To get clearance you need to take 1/2" or so off the back of the handlebar cover so it doesn't rub on the dash. If you turn the hard to the left, there's now a good 2-3" clearance to the screen.

The next job is to take off the mirrors and drill new mounting holes in the screen. The back ones are now 1" higher and the front ones about 1/2" higher. It's a bit of a struggle to get it all back together but it's possible. The screen is now tilted back quite a bit from vertical. Make sure you've still got clearance on full left lock. The top of the screen is now too low, so either leave it like that for more fresh air or add an old helmet visor to the top. Use Duck tape until you've got the position right, then drill a couple of holes to neaten it up.

Next I cut 1/2" off each end of the handlebars as they're too wide. This means filing off the nubbin in the bottom of the switch gear that locates in the hole in the bars and sliding them inwards a bit. You can't get any more than this as the master cylinder doesn't want to go any further round the curve of the bars. You'll have to shave bits off the covers so they still fit.

Now fit some heated grips and wire them to a switch in the dash with a small LED to show when it's on. There are two accessory outlets under the left side of the dash. Bizarrely the switched one has no fuse, while the unswitched one is fused. Wire them to the switched one, so they go off with the key but put a fuse in the circuit.

Finally, while you have the mirrors off bend the stems in a bit. Careful you don't go too far as there's a limit to the adjustment on the mirrors themselves.

The end result. Smooth airflow, comfy hands in the winter, and a narrower machine that can squeeze through smaller gaps. The mirrors are just right so they go over car mirrors and underneath van and SUV mirrors and the widest point of the machine is your hands so it's all easy to judge. The riding position is now perfect for me. I can lean back on the freeway and relax completely with my feet up and forwards, or lean slightly forwards for maximum swerve control in traffic.

I took the cover off the seat and attacked the front riders part with an old hacksaw blade. I've cut the centre of the seat foam down and forwards onto the hump so that there's now about 1/2" of foam instead of 3" I shaved the sides down till it was comfortable but left them a bit higher. The cover goes back on with a staple gun. There are some funny strings that go from the cover through the foam and through the base. *DON'T CUT THESE* Just remove the clips that hold them on the bottom of the seat. I've ended up with a bucket shape seat that makes you a bit more secure, lowers the CoG and is still just as comfortable. It's a good idea to do the seat before you mess with the screen extension so you get the height right. An alternative to the old visor would be a Givi screen and I bet the same effect could be had with that.

Small Stuff

Let's see now, PFM front disk with EBC Kevlar Green pads. This all works pretty well. The old disk was completely shot at 30,000miles. The biggest hassle was the brake caliper. It's supposed to slide on a pin and a steel cylinder that should move in the aluminium caliper. Of course after a few hard winters, it all corrodes together. Anyway, with the EBC pads and cleaned up caliper the brakes are a vast improvement. One of these days, I'll probably put steel braided lines on, but I just haven't got round to it yet.

The petrol tank takes ages to fill the last 3" above the steel cross piece. I've taken a punch and made an air hole just below the weld where the neck joins the main tank. Now I can get the tank completely full in a reasonable time.

The airbox has an oil separation tank attached to it at the front. A breather pipe goes from the cam cover into this and there's two pipes out, one to the air intake and one that goes down near the wheel with a plug. The problem is that the tank is a push fit onto the airbox mount and comes loose. Any oil blowby then sprays all over the belt cover. I cut a piece of an old oil bottle and epoxied it in to the end so that it's sealed even if it comes loose.

Helix have a nasty habit of vibrating the spark plug cap off the spark plug. This seems to be partly because the cable is a bit short, but also because the standard cap is a joke. I fitted an NGK cap and used a file to notch the plug electrode so that the spring has something to catch on. Sorted and no more wet weather misfires.

The two bolts at the front of the exhaust which attaches it to the engine can break or vibrate free. I know of three bikes that have had this happen. I replaced them with longer bolts (85mm?) and put locknuts on the other end. It's a bit of a pain to do them up, but worth it for security.

Last but not least, the scoot is covered in Schwa (gray) Alien head stickers! One big one on the back with "Stay Awake" underneath (Invasion of the Body-snatchers anyone?) and on the steering head is the message "Remain where you are while vehicle is in motion""

The Baglux Lap Cover

Before I start, I should tell you that these things are extremely weird and not for use if you mind people looking at you.

Baglux sell these heavy black nylon covers with nylon fur on the inside. They attach to the bodywork just below the handlebars and down each footwell and then back towards you covering your legs and lap. The instructions are in French and a bit vague so people have a bit of trouble understanding how to fit them. Once you understand it's pretty easy. Once I'd fitted it the first time I went for a ride and was horrified to have it flap away above 50mph making the whole scoot flap with it. Hmmm, more work needed.

The first thing was to stiffen the sides. I folded each side up diagonally inside and used haberdashers pop rivets to keep it folded. The sides now run from my lap down to the feet area. Then there's a piece that your supposed to tuck into your jacket or over your head. This bit was folded and again held with pop rivets. This all nearly did the trick and was now stable to 60mph. The final trick was to add a clip to hold the foot ends to the bodywork a bit further back than the standard springs. Perfect. Stable at 75mph.

I only fit this in the winter (November to March) but it's brilliant. You look like you're in an old people's wheel chair, but there's nothing like being warm and dry. It takes a slight nack to bring your feet back and down to put a foot down, but after 5 miles in traffic it becomes second nature. I find I can ride in jeans in light rain and it's warm enough down to about 0 deg C before I have to think about breaking out the heavy duty clothing.

I think I should tell you now what the scoot gets used for. I commute about 23 miles from home to work everyday through North London. It starts with about 8 miles of WFO dual carriageway, slipstreaming the cars at 70-80 mph. Then there's 7 miles of 2 or 3 lane traffic which is all lane splitting at 40-50 mph, finally 8 miles of dense cut and thrust through traffic. This takes a lot of nerve and aggression to make time between the cars, round the 'peds and bicycles, over pavements and trying to avoid being rammed by suicidal M/C messengers. The modified Helix is the perfect Urban Assault Weapon for this stuff. Very few bikes can get away from me in traffic.

It works even better with some sounds and I usually wear a CD Walkman playing some late 90s dance music (Drum'n'Bass, Trip Hop and Big Beat). This evening I was starting to think about a paint job. I fancy a camouflage pattern but in fluorescent oranges and blues. Clearly time to calm down... God knows what the company's management think about all this but I guess they just put it down to "character".

Drop me a line at julian_bond@voidstar.com if you want further details.