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 by Don SmithAs you look into your garage and stare at your new GSX1300R Hayabusa you can honestly say to yourself that you own the most powerful, fastest and quickest production bike ever made. And now with the new upcoming (self imposed) speed limits on sportbikes the 1999-2000 Hayabusa could go down in history as the fastest internal combustion motorcycle ever mass-produced. So what is next you ask? More horsepower of course!! As you may know the Hayabusa comes with about 155hp and over 90 lb/ft of torque. In 1997 you would have had to buy a Honda Blackbird and cashed in your retirement to get this kind of performance with a naturally aspirated engine. Well that was then and this is now. If you are happy with the performance of your Hayabusa you can stop reading here and just look at the photos. If you want to build the only non-turbocharged , non-nitrous bike capable of beating a Busa then read on. As a basic bike I am assuming you already have a full aftermarket exhaust, either a Power Commander II or access to a Yoshi box for EFI tuning. So I will not be discussing the finer points of exhausts or fuel management. I will say that there are several HP hidden in the bike that can be extracted with the right combination of fuel and timing changes. (I can't tell all my secrets) I have the Yoshi full exhaust system with the stainless header and the polished aluminum canister and have been very happy with it. Now enough about the basics. Let's get to the good stuff. If you want more than 165 or so horsepower you need to get into the engine, deep in the engine including an overbore of the cylinder and valves seats if you want to exceed 200 hp. The goal I set for my bike was to gain an honest 20-25 hp at the rear wheel and not give up so much reliability that I could not still ride it 300 miles or more in a day if I so desired. I settled on a mix of parts and machine work that reached the target HP I was looking for. Your specific performance goals may be different so you may have to go more or less radical with your parts and machining. The first thing I decided on was the cam. After looking at the main two cam manufacturers for the Hayabusa (which is Yoshi and Web Cam). I settled on the Web Cam 536/577 grind for several reasons, one of which was cost. With Yoshi you are getting new billet cams so they are more expensive. With Web you remove your stock cams and send them in and they are welded up and reground and hard plated. I also felt that the Web cam lift and duration specifications were a bit more aggressive than the Yoshi and would be better suited for producing the kind of power I was searching for. See the chart below for a full comparison. I also ordered the adjustable sprockets from Web for easy cam timing adjustment and had them welded by the engine builder to prevent slippage. And finally related to the cam I had a manual cam chain tensioner installed upon re-assembly.
As mentioned earlier I selected Wiseco pistons for my project. As many of you know both JE and Wiseco are making stock bore and oversize pistons for the 1300. I decided not to go with the overbore route in order to keep costs down and maintain reliability as much as possible. As you may know the Hayabusa cylinders like many modern sportbikes are coated. Meaning if you bore it, you then also have to have it replated. The specifications of the pistons are very similar with the JE weighing in at 239 grams and the Wiseco at 223. However the Wiseco had 13.0-1 compression and the JE at 12.5-1. It is not a huge difference I know, but if you want to make big power you need all the cylinder pressure you can get. Below is a photo of the Wiseco I used. I think you will agree it is a beautiful forged piece. I could not find a factory published specification on the stock Suzuki piston so I took them to a local analytical laboratory and weighed them at 222.57 grams.
Just as I have mentioned it is important to
select good parts it is even more important to get a good engine builder. All those
expensive parts are worthless if they are not assembled using the care of a surgeon. It's
the little things like using proper assembly lube and proper torque specs on the head and
cylinder. Adjusting the TPS, synchronizing the fuel injection system, degreeing the cams
and a hundred other things I will never even know about. So for those duties I turned to
one of the most respected builders I could find. He is a one-man shop in Atlanta, GA. and
due to current workload he has requested to remain unnamed. If you really can't stand not
knowing who he is email me (rotts4u@aol.com
) with your project needs and I will see if he is taking any new customers and get back to
you. You can imagine how many inquiries an article like this generates but he just does
not have the staff to handle the workload and extra phone calls it can create.
I could go on an on trying to describe what
186hp feels like but I won't even try. The bike lost a few hp below
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Due to the
design of the Hayabusa frame it is necessary to pull the engine in order to remove the
head. Unlike other bikes which can sometimes have the head removed while in the bike. The
lump on the busa is just too big. While it was out I also took the opportunity to remove
the PAIR air injection system to save a few more pounds. This modification should only be
done on a bike slated for "offroad use" because it is not EPA legal. While the
bike was apart I also installed a second radiator fan on the other side of the bike in
anticipation of the added heat on the already marginal cooling system. While on the
subject of cooling I am also now using the non glycol product sold by Evans that is
reported to increase cooling ability of the stock system as well as increasing the boiling
point to 364 degrees. (
Using the web 536/577 cam you can get
by with the stock springs but they are close to coil bind. So I opted for a new set of
springs. So far everyone is pretty tight with their information on sources for Hayabusa
springs. When I asked Web for some advice on springs as well as who to do the
head-machining Web was quick to point me toward KWS Motorsports in Charleston SC
(843-566-0004). I had met Kevin the owner of KWS last October in Daytona and even that
early in the Hayabusa's life Kevin was offering a full engine kit so I knew he had the
experience on this bike. So the head was shipped to him for some minor combustion chamber
blending and a radius valve job. He also had a source on the valve springs. One thing that
I think is important when building anything as complex as an engine is to make sure all
the parts work well together. You can not always add up parts selected at random and hope
they result in a good engine. Kevin has built many Hayabusa engines using the Web cams,
his springs and the Wiseco pistons, both in stock bore and oversize. So he knows what he
was talking about. Below is a photo of the springs. The old factory springs on the left
and the new KWS springs on the right.
As you know if
you are going to make big power you have to get it to the ground and the stock Hayabusa
clutch design prevents a good drag start. If you are an average street rider or roadracer
the stocker should be left. However if you want to hit it hard when the tree turns green
there is only one way and that is the Brock Davidson clutch modification. It is not an
expensive modification but it really makes a difference.
6000 rpms and the peak moved up from the previous 9899 rpms to 10,257.
Indicating the bike is breathing much better now than before. Since engine machine work
and costs vary from one area to another I am not going to quote any exact costs. However
to get you in the ballpark I will tell that you before you enter into this type of project
you need to budget in the range of $2800-$4000. If you are able to pull the engine
yourself and reassemble it you can save yourself some serious cash. So if you want to beat
a Hayabusa my advice is to get your own Hayabusa and get to work. Otherwise the only ass
that gets smoked this year could be your own.