Although you wouldn't know it, it's actually been six months since I wrote the frame article. The reason? A major motorcycle accident. Well, as I'm sure you can imagine, smacking yourself into the front of a car has fairly disastrous ramifications on your life, some of which I wasn't expecting but then you can never pre-empt the actions of scum, but some of the more obvious ones regard the ability to move - or not, as the case may be. Anyway, I'm finally in a position to get back to working on my idea of the ultimate streetfighting, throat tearing, 'don't fuck with me' barking mad road bike. So, as the last time you read all about the outrageous Steelheart Engineering built frame, it's now time to move on to the monstrous soul of the machine - the engine. First off, it's not a gixer (GSX-R) 1100. Okay, so it looks like a gixer, will go even better than one and will certainly sound like one, it's not one. It is, in fact, a GSX1100F which the sport-touring fraternity will know as Suzuki's 'Power Screen' GSX. Admittedly, there's not a lot of difference between the two engines (although the 'Power Screen' is a lot cheaper to insure, which is what the insurance company class this bike as); change the carbs, cams and crank and you've got a gixer. Two of these changes have already been made to the bike, but one hasn't and won't be until next year. And until the crank is replaced next year the engine has to be limited to 200bhp. Why? Because unlike the gixer that has straight cut gears, the 'Power Screen' comes with helical gears which basically means anything over 200bhp will result in the clutch basket suddenly making an unexpected appearance to the outside world half way through a race. This is not something I personally want to experience as I'm sure you'll understand. But why isn't the crank being replaced now? Simply, I want to get to a point where 200bhp is no-longer enough power on the strip through learning how to race rather than trying to go faster by upping the nitrous. Once my times have stopped improving, which will hopefully be just into the nine seconds region, then and only then will I actually be able to put all those extra horses to good use. Plus, by winter the engine will need to be completely stripped, just in case, anyway. Right, time for the technical reasons behind everything that's been done to the engine. No matter what you do to a motorcycle engine to increase its power, without first working on the head, any other modifications will not achieve its full potential, especially if the mod is a big bore - in the case of Fatalistic Attitude, a Wiseco 1216cc kit. Put simply, without improving the engine's ability to feed the combustion chamber with enough petrol/air for the increased bore size you'll actually end up with less power in the upper rev range. A couple of bike comics last year tested 'tuned' Fireblades for bhp, torque, standing quarters and outright top speed. Every single one that had been stuffed full of go-faster parts, race cans, dyna jet kits, carbon fibre this and titanium that, all went slower than the standard bike. Why? Because the one thing they'd all ignored was the engine's inability to feed itself enough petrol/air mixture to cope with the modifications that had been made. The first part of an engine the fuel mixture hits is the intake port. There are two schools of thought when it comes to tuning this part of an engine. The first is that the port walls should be mirror polished as this increases the flow rate, while the second school believe that, although the port walls need to be smoother than standard, rather than mirror polished they should be smoothed using 1200 grade sand paper. When the fuel mixture travels through the intake port the main flow is in or near the centre of the port, much like a river where water flow is much slower near the bank, however, the fuel flow wets the port walls which results in what's known as a 'boundary layer'. No matter what you do there will always be a small amount of petrol that separates from the mixture which forms puddles on the boundary layer. Polished intake ports allow large puddles of petrol to form which obviously burn inefficiently yet roughened walls, although producing a minutely lower flow rate can help re-introduce the puddled petrol back into the fuel mixture flow. The boundary layer increases in size as the flow increases which can adversely effect the flow's efficiency, even to the point where the boundary layer is no-longer on the intake wall surface, creating whirlpools of fuel. This can be lessened by contouring the port - although I want to write an in-depth article, I think a line has to be drawn as to how deeply into the subject I'm prepared to take you, so I'll leave the explanation at that. Next component on the fuel's journey is the inlet valve itself. This really is where any gains made in both the carb and the intake port can easily be lost yet, unsurprisingly, it's also where more large power increases can be gained. In this case, the flow is mostly affected during low and medium valve lift which is why a multi-angle valve job which balances the valve, valve seat and combustion chamber thus improving the amount of fuel entering the cylinder is incredibly important. As full valve opening only happens once per cycle yet half valve lift actually happens twice, the efficiency of the valve and valve seat is paramount. One misnomer though is that the larger the valve, the more fuel that enters the cylinder. This is not correct. Flow efficiency is relatively dictated by intake tract pressure, and as we all know a large diameter hole will produce less pressure than a smaller one. This is a general statement, however, but if the valve is too large for the corresponding cylinder bore then you'll actually get less power increase than you would if you'd left the valve at its standard size. Of course, once you've got a cylinder full of fuel you then have to make sure that after it's ignited the engine can expel the waste gasses as quickly as possible. The optimum performance you really need is for the exhaust ports to be in perfect harmony with the inlet ports, or put another way, the flow into the cylinder should be equal to the flow out. One thing that isn't required in the exhaust port is the ability for it to keep the air/petrol mixture perfectly atomised which means, unlike the inlet, the exhaust port should be highly polished for maximum flow. Polishing also keeps the temperature high which again increases the flow rate, as well as minimising carbon build-up. As carburettor design is a massive subject on its own, I'm just going to explain why highly tuned motors should run smoothbore or flat side carbs (although, technically speaking, flat sides are smoothbores) rather than butterfly and shaft versions, okay? Smoothbore carbs have a very clean surface, hence the name, where the slide is usually raised directly by the throttle cable, although on Fatalistic Attitude I've used CV flat side carbs. Flat side carbs give far superior pressure drop which increases the venturi's ability to deliver large quantities of fuel at a quicker rate. Obviously, this results in excellent throttle response, as well as improved tractability at low revs not to mention improving peak power. Now to the final component - camshafts. Camshaft design is not an exact science but instead requires a balance between fuel flow rate, bore, stroke, compression, rpm, carb size, exhaust, overall bike weight and the specific purpose of the engine as a whole. The fact the cams also dictate both the torque and bhp curves, there is simply no choice open to engine tuners except trial and error. In this case, rather than having new cams designed, both Big 4 and myself have chosen to use stock GSX-R cams until a time when any problems we may encounter during the coming racing season have been ironed out. Originally, I was going to go into great detail on camshaft design, but after realising just how big an undertaking this would be, camshaft design has been relegated to the same pile as scavenging, squish bands, acoustic wave tuning of intake tracts, combustion efficiency, flame propagation, how to reduce internal friction and design changes required for different fuel types. If these subjects really interest you, there are some excellent books out there that are written by true genius'.