Let there be light.

After yesterday's realization that I had made a mess of my gearing calculations, it feels good to be able to report that the Bates 5 3/4'' old school headlight I bought from a German web shop, looks perfect in its new home between the [still prototype] fork legs of my tracker. Next week it will be adorned by a mesh grille taken from Triumph's accessory program.

And if you think you've already seen that particular combo (black Bates light /Triumph Scrambler mesh) on a street tracker somewhere, you've probably visited the fabulous website of the bike brand with the most pretentious name in biking history: Deux Ex Machina. Their super cool "Mono" has exactly the same combo. In fact, I sent them an email about where that cool mesh came from, and they were kind enough to send me in the right direction.

Originally, I had planned on using a front number plate with a small projector light poking through one of the digits, but since Richard Pollock of Mule Motorcycles thinks number plates on street trackers look "goofy" [see sideburn #3], I went with this setup instead:o)

Bollocks!

Me and my big mouth. I should have used one of those gearing calculators after all (see last post). Instead of lowering the sprocket ratio by 15% I should have increased it by 15%. In other words: I need a larger rear sprocket than standard for my now larger wheel (too make it spin slower). Not a smaller one (which makes it spin faster). In fact, I need a 52 tooth rear sprocket (if I use my 16 tooth front). Learning by screwing up. Now, where did I put that phone number to Talon again?

BTW: does anyone need a 42 tooth rear sprocket for a PM-wheel. Never used...

Gearing.

In its original state, my Husqvarna SMR ran a 48/17 sprocket combo. But that was with the dinky little 17 inchers. Now, with the huge 19-inchers, and the swollen Maxxis flat track tires, we need a different gearing altogether. There is no shortage of "gear calculators" to be found on the web and some are really OTT (here's one), but some simple maths is actually enough.

Here goes: The stock sprocket ratio is 48/17=2,83. The standard tire (150/60-17) had a circumference of about 1,92 meters.The new tire has a circumference of about 2,20 meters, i e about 15% bigger. That means we need to lower the sprocket ratio by the same amount (15%) to get the same "total gearing". 2,83/1,15 comes out to about: 2,46, which is our target ratio. I wanted to keep the front sprocket with 17 teeth and only change the rear sprocket. So I chose a 42 tooth rear sprocket, giving a sprocket ratio of 2,47 which is pretty close to what I need. I've always thought that the original gearing was a little long and I have a 16 tooth front sprocket in reserve should the gearing turn out to be on the long side.

BTW: does anyone know of a company that sells stainless Allen bolts with "countersunk" heads in 7/16''? The ugly hex bolts I'm using now have to go. I've been googling furiously, but to no avail.

The missing link.

My 570 Husqvarna engine has two exhaust ports and two 32 mm stainless exhaust headers. These two headers continue separately all the way back to the muffler (image here), which limits the choice of aftermarket mufflers to a a few specially made for the SMR/TE570. All of these have the same problem as the standard muffler: they are very long and looks terrible on a flat tracker. So, in order to run a smaller and better looking muffler I needed to somehow link the two header pipes into one larger pipe. And as it happens, the more recent Husqvarnas share the 32 mm headers, but use a 2-into-1, Y-shaped connector pipe followed by a larger diameter link pipe back to the muffler. For some reason, this 2-into-1 pipe is not availble as a spare part from the dealers – You have to buy the whole system... But as usual, Ebay came to the rescue, and I was able to find this stainless little time saver (It saved me the work of trying to find suitable stainless tubes, bending and welding them). The part number is A0868. Next up: trying to decide what type of Super Trapp muffler to order...

Rear light.

Another piece of the puzzle falls into place. I've been looking for a rear light on ebay for for some time, but not been able to find a suitable one. They were either too large – most jap/standard bikes use huge rear lights – or just too flimsy/ugly. I've also visited my local breakers yard looking for something that might fit, but to no avail. However, a trip to a nearby place catering to cruiser/chopper types (let's keep that one under wraps shall we), solved my problem. I would have prefered a red lens since I think clear lenses are bit chav, but none was available. So this one had to do. At least it looks well made, and I think the rounded shape snuggles up quite well under the seat unit. I know from experience that the vibey Husky engine kills off lightbulbs at a frightful rate, so I've put some extra rubber bushings between the lamp housing and the "carrier" to protect the diods. The "carrier" (professional builders look away now) started life as a bracket inside a PC, but an hour or so of cutting and drilling later, it now serves a bigger purpose in life. Isn't recycling great?:-)

Heads up.

Now, this may be totally obvious for those of you who've already built a couple of street trackers, but I must admit to have been a little dumbfounded about how to best attach the seat unit and seat pad.

My seat pad from "First Class Glass" came with a set of rubber mounts and screws. You're supposed to push the rubber mounts into the seat base from underneath, make corresponding holes for the screws in the carbon fibre seat unit (the central of the three holes in the picture), thread the screws through the holes and into the rubber mounts. As you tighten the screws, the rubber mounts inside the seat padding expand and lock everything in place. So far so good. But how do you fix the seat unit in place on the frame, without bulky screws and washers between the seat pad and the carbon fibre? An email to the ever helpful J-W of Dutch Brothers gave me the answer: BigHeads. Mine are – as you can see – home made (from stainless), but they do the job perfectly.

Radiator protectors, part 3.

The radiator protectors are now bent into shape and they actually fit perfectly. When painted/anodized black I think they will look quite good. However, if you are going to do this yourself, don't go for 2,5 mm aluminium sheet like I did – it's too stiff and makes the bending very tricky indeed. 2 mm sheet is quite enough, or even 1,5. It's not meant to be bullet proof after all.

And one more thing: I designed little "notches" into the design (see earlier post), to guide me when bending. In retrospect, that was unnecessary and the notches "flared out" in the corners and looks unsightly after bending (probably because of the thick material). I will ask Kent to fill the notches with some weld and then I'll file and sand them smooth again before I send the pieces off to be anodized.

The protectors will restrict the airflow through the radiators a bit, but since the engine has two quite big coolers I think I will be allright. As long as I don't drive too slow:-)