Nine Second Street Bike
What does it take to run the quarter mile in the nine second zone on a near standard street motorcycle? We find out in the first part of our quest to have a faster Hayabusa than that annoying bloke down the street.
This is Part One of this story. Part 2 is HERE Part 3 is HERE
9 Second Street Bike
What does it take to run the quarter mile in the nine second zone on a near standard street motorcycle?
Well for starters it helps if you have something with an abundance of horsepower, in this case a Hayabusa. Or you could try one of the new 1000cc sports bikes like Suzuki’s GSXR1000 or maybe Kawasaki’s ZX10R. In fact any of the 1000cc monsters from the big four would be capable.
Note the comment “capable”, not necessarily achievable for most, nor easily. So we took a stock Hayabusa, and added a few drag strip related tweaks, and headed to the track to find out how hard it was to achieve.
The bike in question is a 2000 model Busa, with approx 30,000 kms on the clock. Being a refugee from a salvage auction, it was resurrected back to stock, with the exception of the paint work, replaced with a more suitable satin black. The standard mufflers needed replacing, so a set of Yoshi cans were bolted on, however with no re-mapping, they possibly only make it sound better, rather than add any horsepower. Otherwise the bike remained stock apart from a welded back torque limiter in the clutch, a recommended mod for harsh clutch treatment on the big Bus.
The hardest part of drag racing a street bike is stopping the wheelie, as any amount of rolling the throttle off to stop it looping, will kill the time. The easiest way to achieve this, is to lower the bike.
A lower centre of gravity means the bike is less prone to attempt to rotate itself around the rear axle, and more likely to propel you down track in a more socially acceptable time.
As with most late model bikes, the way to lower the bike is to replace the suspension link, or set of links, which drops the rear of the bike by a few inches, and using a “lowering strap” to compress the forks at the front. On some bikes you can get some amount of front end lowering by dropping the forks through the triple trees. Be careful though, too little clearance will result in broken parts in expensive places on the front of your motorcycle after a hard landing from a wheelie highlights your lack of available clearance.
So we used the strap, which looks almost like a normal tie down, but has special mounts for attaching to the forks. These also require care in using, it needs to be routed correctly over the triple trees or frame to work correctly. The supplier of the strap should be able to advise you of the best way to fit it.
We used a set of links supplied by Cyanide Racing for the rear, and a front tie down strap from MPE Racing, both in Brisbane.
Once lowered, and ready for take off, thoughts turned to the gearing, and a quick calculation showed that a one tooth smaller front sprocket might be better than the standard 17 tooth.
Then last but not least, a quick check in the mirror revealed that another vital modification was necessary. A lighter rider. Luckily I had on hand a sub 55kg replacement in the form of Rebecca.
The fact that she had never ridden the bike, or indeed any Hayabusa, would make it all the more interesting.
We decided to take the bike out to Willowbank Raceway, and run it in the highly popular Streetbike Shootout event, and get a few familiarisation passes in first. Bike was half filled with fuel and the rear Pirelli Diablo set at 35lbs for a baseline.
Bec ran it slowly down the track on her first attempt, shutting off at half track, just to get the feel of the bike at 160km/h plus, something that wouldn’t have been required if she’d actually ridden it first.
The next run was a slight upping of the pace, again shut off at 3/4 track to creep up on the feel of the bike. Unfortunately, that run also revealed the bike was trying to emulate Exxon Valdez, as a component required to keep the oil in, came ..out. I had forgotten to tighten one of the inspection bungs on an engine cover, leaving only the inspection hole!
By the time this had been replaced, the Streetbike Shootout was over, but luckily for us, a normal Test and Tune evening session was just beginning.
The temperature had fallen, whilst the track stayed warm from the hot day, meaning conditions were close to ideal for its first full pass. Instructions were given.no burnout..hold throttle slightly above idle, launch on last amber, get to full throttle as soon as possible, and shift at redline.
Rebecca didnt let us down, the big Suzuki left cleanly, if a little slowly, but the timing boards flashed up the results of the first run…9.86 seconds at 144mph.
Our happiness at our ease at breaking into the 9 second zone on the first full run, was quickly dampened by a visit in the pits from track management. To ride any motorcycle that runs quicker than 10.00 seconds down the quarter mile, you are required to have a full ANDRA license, along with a bike tech inspection. As we had neither, our fun for the day was over almost as soon as it began, so it was back in the van for the bike.
How fast will it go? After figuring it might take some time to get into the nines, we’ve jumped a few steps already.
We will return to the track when the required forms ,medicals and money have passed hands, to continue the story…
So far, total modifications are:
- Rear suspension lowering links
- Front tiedown strap
- 16T front sprocket (minus 1 from Std.)
Other popular mods on the Hayabusa are not done, like an air box modification, and the removal of the PAIR (pollution) valve. It hasn’t seen a dyno, or even a new set of plugs yet.
A light and capable rider is a huge plus for running a quick time, a 110kg rider will obviously get a different result.
We intend to squeeze more out of the bike with riding technique, tyre pressure, and maybe gearing.
After that we may think about more power via a pipe and mapping.
More Drag Racing articles HERE
