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Project: Bare Knuckled Street Fighter

Discussion in 'Modifications and Projects' started by [FLUX], Mar 10, 2009.

  1. The time has come to formalise my next project bike with its own dedicated thread as sufficient parts have arrived to allow me to commence building it up.

    The Scenario

    I don't do many track days for various reasons, so instead I'm primarily a public road rider. I do a lot of riding on tight roads that do get fairly bumpy at times. I'd been looking into motards to suit, but none are really suitable for long distance riding, and they can be a bit exxy for ongoing maintenance, and are too high-strung for the more performance oriented versions unless you're serious about racing. I was an inch away from buying a KTM 690 SMC, but as the door started to close on the deal I got cold feet about the rather high buy price for what is essentially a big dirt bike with road tyres. I felt I could do it better for around the same price if I custom-built my own bike, and started looking for a suitable base bike to mould into what I wanted. As all good projects do, they start with a set of requirements...

    The Requirements

    • * A half-wet weight of no more than 150kg in road-legal trim. Half-wet means all fluids but an empty fuel tank.
      * Reliable torquey motor good for >100,000kms without requiring frequent maintenance
      * At least 60rwhp at a bare minimum. 80rwhp would be nice. 100rwhp would be great. 120rwhp would be wicked.
      * At least a 200km fuel tank range when ridden in anger.
      * A seat comfortable enough to endure a >600km day of riding without longing for death.
      * A front-end biased geometry and seating position. I've tried motards and nakeds. I can ride them well, but I just prefer a high level of feedback from the front end which motards don't seem to offer me.
      * At least a 220kph top speed. While I don't intend to use that capability on the road, I may go to a track and don't want to be running out of puff on every straight.
    The Goal/Vision

    I figured that it's best if I explain the image I have in my head for this project up front, just to avoid confusion. A best one-sentence summary is a cross-up between a motard, a naked sports bike, and a cafe-racer. I considered buying a number of bike new, outright, such as the Street Triple R, the Aprilia Dorsaduro, KTM 690 SMC, Aprilia SXV550, Ducati Monster, and modifying them. The problem with all of them though was that they are all either significantly heavier than my target weight, or moderately powered, or require extensive maintenance. The Street Triple R came the closest to what I was after but still quite heavy and not a chance of hitting 120rwhp. Heck, I realised that I simply wasn't prepared to compromise on anything less than hitting every single one of my requirements.

    Therefore I opted to simply buy a written off damaged '07 Daytona 675, strip it back to its barest essentials, literally cut stuff off it, pep up the motor and the suspension, and cobble it together back into a street legal fashion using brutal can-do DIY bracketry and lightweight aftermarket items with a single minded purpose: "No bling, only zing!". I weighed a stock format Daytona 675 and it came in at 178kgs half-wet. Phew! That's 28kgs that needs to come off! At least!

    The Wreck

    Here's some happy snaps of the wreck I picked up. It's a 2007 Daytona 675 bought as a repairable write-off with a genuine 750kms on the clock. Frame is straight. Motor is good. Someone has clearly made an aborted attempt to repair it, and given up. Half of what they did was an attempt at a cheap fix. I had to clean up some of their lame attempt as well.

    "The Good Side"


    "The Bad Side"


    The Mods
    Stage 1 - Suspension, Gearing, and Steering

    Getting the 675's suspension sorted for tight bumpy roads is a tricky task, but not impossible. Some of you may have seen my thread researching into the rear-end linkage, and I developed some linkage plates that largely address what I feel is a flaw in the rising rate of the linkage that causes the bike to pitch off larger bumps. The linkage plates also add some swinging range to the rear wheel (to 145mm, up from 130mm), allowing for more travel and a better response to series of bumps by keeping the rear wheel planted. Also due to the greatly reduced weight of the bike a softer 230kg rear spring was used. I opted for the Elka 3-way shock unit here, which has proven to be an absolutely excellent easily adjustable unit with good control for longer rides.

    The stock fork springs are 9.0kg items, and I plan to reduce these to 8.5kg items and have the fork stops milled back about 10mm to extend the fork range to 130mm of travel (up from 120mm). The forks have been pulled through to 0mm of gold tubing showing above the triple clamps.

    Gearing is set to what may seem like a crazy low -2 front, +2 rear (14T front / 49T rear). Sixth gear is now like the stock fourth gear. First gear is great for getting off the line and up to 100kph. Heck, from standstill I can fairly easily launch the bike with the front wheel skimming the entire way and cars certainly disappear very quick in the good old traffic light grand prix. Second gear is now like a very tall first, and on tighter roads it is now perfect. The bike now pulls with very strong forceful drive out of slow 30kph hairpins without being peaky or uncontrolled, and without feeling like you're waiting for the engine to spin up into its upper power range. Third is exactly like the old second gear used to be, fourth is now like a short third and ideal for >100kph cornering work. I find that I don't use fifth that much (like a taller stock third), and sixth is purely for highway cruising. You may think that fuel economy has fallen through the floor with these gearing changes, but honestly I've not noticed any change at all. All up I am extremely happy with the gearing selection given the bike's intended purpose. Flat out bouncing off the rev-limiter in 6th gear, it'll do an honest 220kph (mathematically derived), and really I don't go anywhere near that ever anyway, so it's not like the loss in 30kph of potential top-speed is something I'll ever notice at all unless I visit a high speed race-track which is not what this bike is for.

    Steering on tight roads is all about control and leverage. A 675's low and narrow clipons are great for hanging off and dragging a knee around a race-track, but in the real world do impact bar leverage and control at slow speeds unless you hold them pretty much right on the bar ends which is what I found myself doing often. They are also set too low for such work too as the rider needs to sit a bit more upright for balance (I find) and the bar angle is all wrong for doing that. Still, I also wanted to keep the ability to get low and over the front for higher speed corners, so rather than going with full motard style raised bars I've opted for 20mm raised adjustable clipons. This allows me to set the clipons at a very wide stance (almost as wide as a dirt bike), yet still forwards and still somewhat low. The height of the ends of the bars are about level with the top triple clamp and set at a comfortable natural angle that the palm falls flat onto, but are also more forwards than the stock bar angle. All up it's a fairly natural comfortable position that allows for upright shenanigans, as well as hanging off as needs. The total bar width, end to end, is a good 5cm wider than on a stock 675, but also at a more tangentially efficient angle for exerting counter-steering pressure. I rode the stock bike like this for a while in otherwise full 675 trim and I'd have to say that it was one of the single best mods that can ever be done for improving the steering response of a sports-bike on public roads. Steering is now so light, sweet, and controlled you honestly feel like you can put the bike anywhere you want, and if you don't like where you are now, changing one's line a dozen times mid corner to weave through debris while cranked over is an absolute snap. It's hard to fully express just how easy the bike is to steer now.

    Stage 2 - Weight Reduction

    There's a whole host of weight reductions that I've performed on this bike. A fair bit of it has been in simply removing fairings, brackets, all traces of pillion accommodation. As much again has come from replacing the exhaust system with a light-weight aftermarket full system. The rest has been through selective identification of heavy parts and replacement with light-weight aftermarket alternatives. The weight reduction is still a work in progress and incomplete, but I have a good idea of where the bike's at (have weighed at) and what's left to gain from replacement of other parts.


    Current Bike Half-Wet Weight:____151.5kg
    Predicted Weight Loss To Come:____6.5kg

    Stock factory trim 2007 Daytona 675


    Predicted Final Weights of Project Bike

    Dry (Equivalent*):_____133.0kg

    * - This is different to the wet-dry weight difference of the stock bike due to the different battery used.

    Stage 3 - Engine Performance

    To come. Want to first see where I'm sitting with the lighter rear rim, exhaust and a full ECU remap, and the first stage will be to install higher compression gasket, pistons, and valves. I don't want to go too nuts here on engine performance to the point that engine life starts to become compromised, but some more zing especially in the mid-range, and the final target of 120rwhp is where I'm aiming with this. Unsure if I can achieve that though.

    What it looks like now (9th March 2009)

    Click on images for larger pictures:


  2. interesting project stew, looking good so far
  3. It's hideous. I love it.

  4. niiiice!!!
  5. Wait 'til you ride it mate, you'll be expectorating another ten lines of drool. Just let me get this injection mapping sorted and the suspension dialled in a little better to suit the MUCH lighter weight. The fuelling is decent now, but it's missing the famous mid-range punch of the 675 triple motor, and instead feels more like a Gixxer 750 spinning up. The suspension is about 4-5 clicks away from perfection.
  6. Wow, mean lookin' lil' bugger. :)

    I love the "good side"/"bad side" photos of the original Daytona too!
  7. You're planning on ruining motorbikes for me, aren't you Stew?
  8. Stew, that is going to be an awesome bike. I love that pipe, looks (to me) a mix of retro and modern.

    I wonder what caused the bike to be a write off?
  9. I'm a noob.
    Today I discovered the Daytona 675. It's got many features that appeal to me but mostly the "narrow" aspect of the bike.
    Today I discovered your thread.
    Today I learned the meaning of jealousy.
  10. LIKE.

    When's the production model coming out? :LOL:
  11. Thanks guys. Here's some links to some full-quality pictures taken in the cold hard light of day, which exposes a number of wiring sins, my "masterwork of bodge" home-made custom fender/instrument brackets, bug-splatter, and so on. You'll also have to forgive my camera's absolutely shite ability to reproduce the redness of the tank in bright sunlight. What appears as deep red to the naked eye, comes out as yellowish-orange with this camera. :roll:

    Oh, and don't look too carefully at the front rim either. :oops: :wink:

    Pic 1

    Pic 2

    Pic 3
  12. Never was a fan of street fighters, and those photos remind me why.
  13. When I were a wee lad, I used to judge books by their covers too. :LOL:
  14. That ZARD would have a nice tune on the triple stew. Not like you to have a multi colored bike tho?
  15. Looks, schmooks, this is awesome. I love the build your own ethic, chasing the ideal. Kudos.

    Is there a point where the lack of weight compromises the bikes stability? Do you think it will need a higher spec steering damper? You've still got clip-ons, so I imagine your body weight over the front helps.

    Are you gonna chop the sub-frame to save a little extra? Too many questions. Best of luck with it.
  16. Cheers mate.

    Actually it has no damper. I removed the stock unit. I've altered the geometry to tilt it backwards a little more which stabilises the bike. As it stands the bike has about a 55% frontal weight bias, which may seem odd but it helps the bike to accelerate more quickly as the front doesn't pick up anywhere near as easily as you might think for such a light bike with a powerful motor. Make no mistake, the front gets light but the wide handlebar stance makes it a snap to control. Rode over some pretty nasty bumpy roads yesterday and the front didn't even shake once aside from a quick singular twitch back into line when the front wheel touched down again after momentarily leaving the road a few times over the bumps under acceleration.

    The bike never feels unstable as such. It moves around more than a heavier bike does for sure, but it's more of a "reed in the wind" kind of comparison, rather than fidgety, twitchy and flighty.

    The bike is fitted with an aftermarket sub-frame which weighs about 1200g in total by itself. The ducktail is light-weight fibreglass and weighs about 500g. The rear fender bracket for the indicators + rego plate weighs just 200g. The under-fender has been chopped back and weighs about 300g, and holds the battery which is a 4.6Ah dry SpeedCell type that weighs just 600g. The rider's seat is the only other thing. ie. there's not a lot left to lose from the rear.
  17. looks great stew!

    who's going to be building the motor for you?

    back yard is coming along nicely as well :cool:
  18. What brand is the CF front rim Stewy? I like. A lot. (The whole bike that is) :)
  19. I have a pretty fair idea that's what gives good feel and feedback from the front end as well. My 400 has a distinct front weight bias and I've yet to ride anything that offers the same sort of feel at the limit of sports tyres traction. Could be wrong though :)
  20. Aah, heya flux ol forum buddy.. Here you are whoring up your new baby..

    Not enough to win bike of the year on the triumph675.net forum.. You're going to try for it again eh? haha