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I've got some time to kill so I guess I'll describe some of the mods I've done to my Hayabusa over the years.
When I first got the bike it had some Yoshamura cans on it but was otherwise stock. I took it to the drag strip and one of my first runs down the track was a 10.10 at something like 139mph. My wife came with me and shot some video (http://homepage.mac.com/emarsh/iMovieTheater7.html). Of course I wanted to get the bike into the nines and so I started to make some minor modifications.
The very first thing I did was to do a "small box" air box modification, make a homemade TRE and put on a PC II. I then added a HMF Bigbird pipe.
The next changes I made was to slam the bike and strap the front end. That was enough to get the bike into the 9.90s. By changing the rear sprocket to 42 teeth I got the bike into the 9.80s.
I made a few other changes that didn't really seem to make a big difference in terms of E.T. I put an intake cam on the exhaust side and degreed it in. This was good for a pretty good bump in quarter mile speed (up to 144-145) but killed torque down low. At this point I was running low 9.80s pretty consistently with some 9.70s.
My next mod was to try a 40 hp dry shot. This immediately boosted my quarter mile speed to about 152 mph but it was hard to get it to help my E.T. much. To build E.T. it's necessary to get the power applied as soon as possible but hitting the 40 shot in first would tend to lead to wheelies. Here's a video where I went 9.53 with a 40 shot but for some reason the MPH isn't very good: http://homepage.mac.com/emarsh/iMovieTheater10.html
When I came on a l long deal on a street turbo kit I bought it. To cut the compression down so that I could use the turbo it was necessary to put a spacer plate under the cylinders. As long as I had the cylinders off I replaced the stock pistons with an over sized set to bump the displacement to 1397cc. I also returned to a stock exhaust cam and degreed the cams in. To hold the power I replaced the clutch springs and added a clutch slave cylinder support. I actually moved up to an 18 tooth front sprocket to make the bike cruise better on the street.
The first time I took my bike to the track with the turbo I just threw a junk tire on. The first time down the track the bike spun the tire to about half track then hooked up and started to pull. The E.T. was terrible - something like a 10.30 but the MPH was about 158. After a couple more smoky runs I managed to run a 9.7 at 160 MPH spinning the tire badly.
The bike was fun to ride on the street, but more for show than for go. Problem is that as soon as it started to make boost it would light the tires up at most any speed below 120. Fun, but not entirely practical. I tried a water injection system to protect the engine internals but didn't use it much.
I added a boost controller and then took the bike out a few more times and managed to get my elapsed times down into the 9.30s with some pretty poor 60 foot times (1.60s). In retrospect I think that going to the 18 tooth front sprocket was a bad move for the track, but at this point my Hayabusa was a street bike, not a race bike. It was not mile per houring very well and when I added a data acquisition system I discovered that my boost was actually peaking at about 9500 and then started to fall off. This caused the bike to feel strong but not really make the power that it should have. The bike started to jump out of gear before I made much more progress.
I pulled the engine and discovered that the shift forks had been pretty badly chewed up. While I had it apart I had the transmission undercut, replaced the connecting rods with a stronger set, did the same with the valve springs and machined the head, cylinders and cases for 1/2" bolts. I also installed a multistage lockup clutch and a low profile oil pan (to get the bike lower).
I have returned to a 17/42 gearset and to make the bike launch I've installed a Penske lockdown shock and cut and lowered the fork tubes. I also replaced a number of fueling system components, such as the FMU, pump, and pressure regulator. Other than that the only significant change I've made was to add a CO2 operated air shifter and some more instrumentation, including a two step. And finally, I did put a low profile front tire on an a matching fender.
So that's more or less it at this point. As time goes by I'm sure I'll make some more changes, but in a way the bike is not all that radical, other than the addition of the blower. If the bike was not lowered it would make a pretty good street bike, except for that bad habit of blowing the tires off.
After months waiting for some parts, I just got the bike on the dyno last Saturday and will spend some time at the track tuning the clutch and boost profile. Hopefully I'll manage to get down the track with some decent times.
In retrospect, some of the changes I made seemed to make a significant difference and others did not. For example, the pipe really didn't make a big change, perhaps a few horsepower, for the cost. It built some more top end but at the expense of a lot of torque down low. Probably the best bang for the buck is the 40 hp nitrous dry shot kit. The down side is that the bottle runs dry pretty quickly.
On the drag strip some of the biggest cheap gains can be had by simply strapping and slamming the bike and putting a 16t front sprocket on. This should be enough to put any good running Busa into the 9.90s - 9.80s or better.
To some extent it is because of my experiences with the Hayabusa that I'm not modifying the Kawasaki. These bikes are well enough engineered that things like a pipe just don't make that much of a difference, unless extensive engine work has been done. I may eventually remove the secondary butterflies on the Kawasaki and remap it, (to increase the low end torque) but that's an article for another thread.
When I first got the bike it had some Yoshamura cans on it but was otherwise stock. I took it to the drag strip and one of my first runs down the track was a 10.10 at something like 139mph. My wife came with me and shot some video (http://homepage.mac.com/emarsh/iMovieTheater7.html). Of course I wanted to get the bike into the nines and so I started to make some minor modifications.
The very first thing I did was to do a "small box" air box modification, make a homemade TRE and put on a PC II. I then added a HMF Bigbird pipe.
The next changes I made was to slam the bike and strap the front end. That was enough to get the bike into the 9.90s. By changing the rear sprocket to 42 teeth I got the bike into the 9.80s.
I made a few other changes that didn't really seem to make a big difference in terms of E.T. I put an intake cam on the exhaust side and degreed it in. This was good for a pretty good bump in quarter mile speed (up to 144-145) but killed torque down low. At this point I was running low 9.80s pretty consistently with some 9.70s.
My next mod was to try a 40 hp dry shot. This immediately boosted my quarter mile speed to about 152 mph but it was hard to get it to help my E.T. much. To build E.T. it's necessary to get the power applied as soon as possible but hitting the 40 shot in first would tend to lead to wheelies. Here's a video where I went 9.53 with a 40 shot but for some reason the MPH isn't very good: http://homepage.mac.com/emarsh/iMovieTheater10.html
When I came on a l long deal on a street turbo kit I bought it. To cut the compression down so that I could use the turbo it was necessary to put a spacer plate under the cylinders. As long as I had the cylinders off I replaced the stock pistons with an over sized set to bump the displacement to 1397cc. I also returned to a stock exhaust cam and degreed the cams in. To hold the power I replaced the clutch springs and added a clutch slave cylinder support. I actually moved up to an 18 tooth front sprocket to make the bike cruise better on the street.
The first time I took my bike to the track with the turbo I just threw a junk tire on. The first time down the track the bike spun the tire to about half track then hooked up and started to pull. The E.T. was terrible - something like a 10.30 but the MPH was about 158. After a couple more smoky runs I managed to run a 9.7 at 160 MPH spinning the tire badly.
The bike was fun to ride on the street, but more for show than for go. Problem is that as soon as it started to make boost it would light the tires up at most any speed below 120. Fun, but not entirely practical. I tried a water injection system to protect the engine internals but didn't use it much.
I added a boost controller and then took the bike out a few more times and managed to get my elapsed times down into the 9.30s with some pretty poor 60 foot times (1.60s). In retrospect I think that going to the 18 tooth front sprocket was a bad move for the track, but at this point my Hayabusa was a street bike, not a race bike. It was not mile per houring very well and when I added a data acquisition system I discovered that my boost was actually peaking at about 9500 and then started to fall off. This caused the bike to feel strong but not really make the power that it should have. The bike started to jump out of gear before I made much more progress.
I pulled the engine and discovered that the shift forks had been pretty badly chewed up. While I had it apart I had the transmission undercut, replaced the connecting rods with a stronger set, did the same with the valve springs and machined the head, cylinders and cases for 1/2" bolts. I also installed a multistage lockup clutch and a low profile oil pan (to get the bike lower).
I have returned to a 17/42 gearset and to make the bike launch I've installed a Penske lockdown shock and cut and lowered the fork tubes. I also replaced a number of fueling system components, such as the FMU, pump, and pressure regulator. Other than that the only significant change I've made was to add a CO2 operated air shifter and some more instrumentation, including a two step. And finally, I did put a low profile front tire on an a matching fender.
So that's more or less it at this point. As time goes by I'm sure I'll make some more changes, but in a way the bike is not all that radical, other than the addition of the blower. If the bike was not lowered it would make a pretty good street bike, except for that bad habit of blowing the tires off.
After months waiting for some parts, I just got the bike on the dyno last Saturday and will spend some time at the track tuning the clutch and boost profile. Hopefully I'll manage to get down the track with some decent times.
In retrospect, some of the changes I made seemed to make a significant difference and others did not. For example, the pipe really didn't make a big change, perhaps a few horsepower, for the cost. It built some more top end but at the expense of a lot of torque down low. Probably the best bang for the buck is the 40 hp nitrous dry shot kit. The down side is that the bottle runs dry pretty quickly.
On the drag strip some of the biggest cheap gains can be had by simply strapping and slamming the bike and putting a 16t front sprocket on. This should be enough to put any good running Busa into the 9.90s - 9.80s or better.
To some extent it is because of my experiences with the Hayabusa that I'm not modifying the Kawasaki. These bikes are well enough engineered that things like a pipe just don't make that much of a difference, unless extensive engine work has been done. I may eventually remove the secondary butterflies on the Kawasaki and remap it, (to increase the low end torque) but that's an article for another thread.
