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GSXR 750 K4 Modifications


By: Jay Adair | Published 08 June 2006, 16:05 | Views: 17,062 | tags: bike reviews, suzuki, gsx-r 750
Like most bikers, when I bought the 750, I had every intention of keeping modifications to a minimum as so not to get carried away with spending money on something I probably wouldn't get a full return on. But like someone famously said 'no battle plan lasts the first encounter with the enemy', and in my case, this meant the track. I was becoming more and more taken by trackdays, so with this in mind it was quite easy to justify a few modifications that would make the bike easier to ride fast, or if the worst were to happen, to minimise crash damage. To this end, I start modifying the bike to make something special in my eyes and that I felt utterly comfortable on, whilst at the track.

The following is a break-down of the modifications I had done since purchasing the bike, and the reasoning behind them (to follow). The majority are performance-orientated, but I give in from time to time and add some cosmetic items to improve the overall look of the bike, in my eyes.

If I stopped to calculate how much I've spent on top of the bike purchase amount with these modifications, I'd probably have a heart-attack. At the end of the mods (the bike has now been sold), I'm left knowing that I owned a bike that made me smile every time I looked at it, and made me chuckle every time I rode it hard. The money aspect doesn't come into it, it's a labour of love and I'd do it again, and again...

View the K4 750 Gallery.

* Akrapovic carbon fibre bolt-on exhaust
* Ohlins 46PRXLS rear shock
* Brembo 19x20 radial master-cylinder
* Power Commander 3 USB
* Custom fueling map for PC3
* Dynojet Quickshifter
* BMC race air-filter
* Woodcraft clipons
* Renthal soft-grips
* Gilles rearsets
* Watsen front flusmount indicators
* Custom toe-guard
* SJP quick-release tank posts
* Digi Gear indicator
* Goodridge braided hoses
* SBK3 performance brake pads
* Full R&G crash-bung kit
* Onboard video system
* AFAM 520 race chain
* Renthal sprockets
* Numberplate holder
* Suzuki carbon accessories
* Pillion-peg removal
* Metzler Racetec tyres
* NRC armoured engine cover
* Harris exhaust hanger
* Suzuki Gel-Seat
* Puig tinted double-bubble screen
* CRG fold-up clutch lever
* Tapeworks.com overlay decals
* Braking wavey rear disc

Akrapovic carbon bolt-on exhaust

This was the very first bolt-on to go on, after exactly 4 miles and twenty minutes from picking the bike up from the dealer, the standard exhaust was taken off and the Akrapovic added. It makes the sound of the bike come alive, much deeper sounding on low-rpm and screams silly when you're nailing the bike. This gives a performance increase of about 4bhp over stock and is much lighter that the stock item. It's as much a cosmetic modification as anything though. You can't go wrong with an Akrapovic item, they're very well made and last the course.

Ohlins 46PRXLS rear shock

This was one of the latest additions to the bike and came about through being advised that these shocks are significantly better than the stock items when at the track, where the stock one can overheat and not provide as good damping, meaning you can get better traction and adjustability out of the Ohlins unit. Looks amazing on the bike and provides a very plush ride.

Brembo 19x20 radial master-cylinder

The stock Nissin radial master-cylinder is certainly not lacking, it allows the bike to have one of the best braking setups on any production bike, but the Brembo unit provides increased power whilst retaining the levels of feedback provided by the stock unit. It also looks incredibly trick and compliments the whole braking system upgrade.

Power Commander 3 USB

This was a new item to be added, and as of yet isn't running a custom map, so isn't adding anything to the performance of the bike. Once the custom map is created (very soon) then I can expect a much smoother power delivery, better throttle response and a performance increase.

Dynojet Quickshifter

This plugs into the Power Commander and allows full-throttle up-shifts, which makes the bike much smoother to ride around the track. It gives you some extra speed on the straights, but more importantly when you're in a corner and want to change up, it won't unsettle the suspension as you won't be letting off the throttle. It also sounds amazing coming down the straight for spectators.

BMC race air-filter

This air-filter is free-flowing than the standard one, letting in more air, so you get a bit more kick up the top-end of the power-band. This compliments the Akrapovic exhaust nicely as the engine can breath easier overall, giving more power. It's also washable, so you just take it out, throw it in the washing machine and you save yourself £50 a go on new filters.

Woodcraft clipons

These race items are totally adjustable for length and angle, so you can get a much better arrangement for your arms. Having them wider means you have more control over the bike and more leverage, making it easier to turn the bike mid-corner with some counter-steer. The bars themselves just unslot from the clamp, so if you do drop the bike, you just spend £8 on a new bar and plug it all in. You don't need to take the tripple-clamp off to do this. They also look quite trick up-close.

Renthal soft-grips

These simple items take five minutes to put on the bike and give a bit more feedback and are gripper, so make the bike a bit easier to control. It's a small benefit really compared to the other mods, but it helps it all come together, and compliments the clipons.

Gilles rearsets

I'm quite happy to admit that these are every bit as much for asthetics as they are for performance. The standard rearsets that Suzuki provide are ugly and completely spoil the look of the bike in my opinion. These rearsets are completely adjustable for peg position and lever heights. Having the pegs higher and further back means you are in the race-position all the time and make the bike a bit easier to flick from side to side, which is very useful on the track. They're also pretty much indestructable and the pegs don't brake off easily in a spill, unlike the stock ones.

Watsen front flusmount indicators

Mr Watsen runs a small firm in Canada making these indicator units, they're in high demand and people wait about six months to get hold of some. What makes them special is that the build-quality cannot be bettered and they really compliment the lines of the bike. They're powerful enough and come with resistors to slow the flash-rate down to standard. They're expensive but then so was the bike in the first place, why add cheap tat to an expensive bike?

Custom toe-guard

To get this fitted onto the swing-arm, I had to force a thread onto a drain-hole, use some loctite on the bole to secure it and then superglue the remaining length was super-glued on. I had to paint this item black myself, but if you notice the bottom edge, it's been scraping when the bike's lent right over in a turn, so needs touching up. It gives the bike that race look and theoretically will prevent my toe going into the sprocket if I were to come off the bike awkardly.

SJP quick-release tank posts

These are another cosmetic item that give the bike a race-look. A friend out in the states makes these sort of items for a reasonable amount and make the bike a bit easier to work on as less tools are required to dismantle the bike, plus it looks tidy.

Digi Gear indicator

The gear-indicator was added mainly for the benefit of the onboard video system, so I could get a picture of the gear, revs and speedo, meaning I could review my performance later on. It's also quite useful on the road, stopping me searching for a seventh gear all the time, and making sure I'm in first when at a traffic-light, stopping any embarrasing stalls from whilst pulling away in second.

Goodridge braided hoses

People often don't understand just how much a joy it is to ride a bike with strong brakes. When you're on the track and want to out-brake someone, you need power and feedback, so you can trail the brakes up to the apex of a corner. These braided hoses go some way to improving strenth and feedback, but mainly help to eliminate brake fade later in the session.

SBK3 performance brake pads

These go hand-in-hand with the above and increase overall stopping power, allowing you to brake later and make a corner.

Full R&G crash-bung kit

I've always sworn by R&G crash bungs, but actually tested their effectiveness after three weeks of having the K4, I low-sided the bike at Silverstone GP whilst doing a very wet-trackday on near slick tyres, not good. The bike slid along the ground at about 45mph before hitting the grass and stopping. Only the fairing and swingarm bungs were worn, and the engine cover scratched. The fairings were completely untouched! The cover got a good sanding and a respray and was as good as new.

Onboard video system

I have an onboard video system fitted to the bike to allow me to review my track performance and see where I can improve, and also to have some fun and share the footage on my site. This is documented in detail in another article, go check it out.

AFAM 520 race chain

The race chain is a 520 format, which means it's thiner and lighter than the standard 525 format one. This means it'll accelerate quick and carries less momentum, allowing the bike to be more agile and stop quicker. Also, just like the MotoGP, AMA and BSB Suzuki bikes, it's blue. Some people like it, some people don't. I really like it.

Renthal sprockets

These are lighter than the standard ones and look a bit nicer, but the main reason for having them installed is to change the final-drive gearing of the bike. These bikes have a very high terminal speed, which won't be achieved on U.K circuits, so why not take some of that top-end speed and use it lower down? By having a one-tooth less front sprocket, the bike accelerates quicker, but at the expense of some top-end speed. This is one of the best and cheapest performance modifications you can do to a bike. Go give it a go, you'll be doing power-wheelies everywhere.

Numberplate holder

Who wants a giant air-brake on the back of their bike? Let's see those natural lines Mr Suzuki wanted us to appreciate. This was a £12 Motrax item bent and cut into shape. Not all mods have to cost a lot.

Suzuki carbon accessories

These really finish off the bike from the riders point of view, they smarten up the instrumentation and protect the gas cap from damage. Another cosmetic indulgence.

Pillion-peg removal

These get changed on and off fairly regulary for taking friends out, but when they're not on, the lines of the bike are much smoother and it looks a bit racier. I have a black exhaust bracket to go in place on the right-hand-side.

Metzler Racetec tyres

I normally run Super Corsas now on track and road, but thought I'd try out Metzlers new tyre. Pirelli and Metzler are effectively the same brand, their tyres are made in the same factory, so it's not much of a leap of faith. These new tyres are exceptionally sticky and keep VERY warm for a longer amount of time whilst inbetween sessions, meaning you don't have to take it easy for the first two laps, you can just ride hard to the front, and then give it near 100% after the first lap. They have amazing mid-corner grip and also slide well, rather than just give without warning, or high-side you. I had these sliding out of three corners at a trackday at Silverstone GP the other week.

NRC armoured engine cover

The engine covers on modern sportsbikes are made to be light, not strong, so it can be a real dissapointment to lowside a bike, sustain minimal damage, only to notice that you've put a hole in the engine cover, ending your riding for the day. These armoured items are far stronger and able to take much more damage that the stock item, a race-proven design.

Suzuki Gel-seat

This was bought for a long ride which won't happen, but it's amazing how much better than the stock one it is. It's far more comfortable, looks very nice and is well finished. It also has the added benefit of being quite slippery with leathers on, so on the track when transitioning from knee to knee in fast corners, I won't have to hover above the seat, I can just slide over, making me less tired through the session/day.

Puig Double-Bubble screen

I picked this up off eBay as there are no UK distributers. It pushes the air when at speed, over your head, so there's less buffeting, which means it's easier on your neck and quieter, so you can concentrate on going faster. I waited a while to get one of these as I wanted to see how they looked on other peoples bikes, as after-market screens have a tendency at times to ruin the look of a bike, but I like this one.

CRG fold-up clutch lever

The idea with this addition is that in the event that the bike is dropped of if a spill happens, the lever end will fold-up when struck and if all goes well, not break off leaving the rider with no clutch control. The design makes it very nice to grip and is fully adjustable for span by rolling the dial on the top face.

Tapeworks.com overlay decals

The fairings have the '750' and 'GSXR' as orange coloured by default, but I wanted to change this, so tapeworks.com in Southern Carolina, USA, was enlisted to make some overlay decals to change the colour to a chrome look, which makes a subtle but yet very important change to the look of the bike. Obviously there's no performance benefit here.

Braking wavey rear disc

This item is lighter than the stock item and as the edges are waved, they brush against the caliper discs increasing the bite a small amount, though mainly it's a cosmetic addition, but any reduction to the unsprung mass is a good thing obviously.


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» Jay's GSXR 750 K4

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