WEIGHT BIAS FORWARD?

[OB_Dirty Pete]

I have not read in any source what the front/rear weight balance of the Busa is, compared to other bikes.

Does anyone know the answer or have the facilities to determine this? I'm not sure I'd trust my bathroom scales, or whether that simple a weighing is the right way to do it.

I feel the bike is quite biased to the front compared to other sport bikes I have ridden.

At the track, the Busa is unusually hard on front rubber. But I feel more comfortable pushing the front on this bike than any other I've ridden. It pushes out really progressively.

My track instructor thinks it's because The Lump (British for motor/tranny) is heavy.

I also suspect the forward weight bias, if that IS the case, has a lot to do with the bike's rock steadiness at high speeds. The steering damper helps of course, but lots of bikes have that and still get head shake at 140 mph plus.

Busas will go to the redline in 5th and never shake.

Maybe it's not all aerodynamics?

The bike does not wheely like a GSXR1100 and many other bikes. It goes into front pushing sooner than others do.

What do the engineers in the forum, like Bob, have to say?

 

[Gixx1300R]

I read somewhere that the Busa is balanced 51/49

 

[OB_Dirty Pete]

OK, sounds like perfect balance. So why am I getting my heavy front tire pushing? Is it just because other sport bikes are lighter, or perhaps I'm crowding the front end as a rider.

I weight 190 and never let my ass touch the hump on the street or track.

I've always got my crotch in contact with the tank. For this I pay a pain penalty sometimes.

Where do others of you put your weight on this bike while you're into heavy cornering?

 

[Frank Adams]

peter,
turn down your fork springs one line on each side at the top of your forks and you'll see that you have a hole new ride...

 

[OB_Lisa]

Here is a link that may give you a little advice on suspension changes....
http://www.motorcycleworld.co.uk/biketests/mcn/solo/hayabusa/close.htm
About midway down the page it talks about changing the compression and rebound, haven't tried it myself, but probably will on the next big ride I do. I find the rear end gets very squirly with hard braking.

 

[OB_Dirty Pete]

HAYABUSA AND FRANK... je suis idiot!

I wrote that request for a clarification of Frank's pre-load adjustment info at work while my bike was at out of sight at home and remembered the adjustment nut layout from memory...incorrectly. Stupidly, in fact.

Of course you're right and pre-load is on both sides. I did that a long time ago and after some fiddling, have been satisfactorily adjusted at three lines showing for months.

Too bad. I was hoping Frank had another secret adjustment for me!

BOB and BADBUS: I think you're right. On the Busa it's easy to forget how much weight you're carting around, as the bike handles so nimbly. The extra tire damage must be occurring on the turn ins and during apexing when the front is fully loaded, and not when the tire is being pushed on the exit. On exit, the front is pushing because it's unloaded, not because the front end is heavy.

Thank you all for your input.

Tires: A tax on Hayabusa owners



[This message has been edited by Dirty Pete (edited 02 September 1999).]

 

[OB_Dirty Pete]

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[OB_Dirty Pete]

FRANK, I reefed all my suspension settings down very tight a long time ago, front and rear. I'm as tight as I can bear it on the street, which is perfect for long, fast tracks.

Sorry, I don't understand what you are suggesting. The only front adjustments I'm aware of are rebound and compression damping screws on each fork leg, and the single pre-load nut in the middle of the triple clamp, which you can adjust line by line. How can I "turn down the fork springs one line on each side at the top of my forks?" Is this this an internal adjustment that requires disassembly?

LISA: Thank for the URL, that setting was my start point when I tightened up my suspension months ago. As for your squirrely rear end, are you using rear brake? If so, you may decide to train yourself to use front brake only after reading the debate on that subject in emattson's topic named "Add your safe riding tips."

Also, since you are using your Busa on the track (are you still track riding it after your spill?) I would recommend you tighten up your suspension right away. The settings in your MCW URL would be a little too tight for you at 160 pounds, so just back them all off a little and make that your starting point.

 

[OB_badbus]

51/49 weight bias is at rest. There is a lot more weight on your front tire under extreme braking into corners. The Busa is a heavy bike with lots of speed, getting that puppy down to cornering speed is not an easy thing to do for such a soft compound tire. I think this may be causing the accelerated front tire wear and pushing.

[This message has been edited by badbus (edited 02 September 1999).]

 

[OB_hayabusa]

Sorry Dirty Pete, the centre nut is not the Preload adjustment, that just holds the front of your bike together.

The front preload adjusters are the gold hex nuts under the rebound damping slots. If you turn these clockwise you increase the preload.

 

[OB_VegasDude]

Hey dirty pete, i just learned a suspension secret, I lost 12 lbs in the last three weeks.........helped considerably.........

 

[OB_Boss]

Head Stem lifter I have won't lift Busa!!!
Weighed front wheel on scales (attached to bike of course) and there is 109 Kg of weight on the front wheel????????? Boss

 

[OB_Bob]

The Bus weighs 550 lbs. plus you-740 lbs. moving at high speed. Physics is your problem. Not much you can do, other than optimize you entry speed BEFORE the turn.
The engine/trans. in this bike have an unknown weight for me. Anyone know? This could be the price for 1300 cc's and 165+ HP.
True SuperBikes weigh, as you know, ~400lbs.
#1 BUSA goal was straight line speed performance, everything else is a compromise.
Bob

 

[OB_Dirty Pete]

Terra, your point about 600 vs 1300 front contact patches is true and revealing. I hadn't thought of that. It explains my earlier complaint about not having this problem with other sportbikes.

In track cornering, I dive in going as fast I can and get on the throttle as early as I can. You have to do both.

Could you please explain in more detail what you did to your rear rotor? I'd like to neuter that sucker too.

[This message has been edited by Dirty Pete (edited 03 September 1999).]

 

[OB_Dirty Pete]

Vegas...no poop, dude.

There's a couple miles an hour hanging around my belly.

I'm no chub (6', 190), but could take 15 pounds off and save some front tire rubber!

And eating lettuce is cheaper than buying titanium...

 

[OB_terra1]

If you are pushing the front, you might try a slower corner entry with earlier throttle, which will shift weight rearward and unload your front tire. Obviously don't overdo it or you overload the rear, but the rear is much wider and has a bigger contact patch.

The real problem is that 600s and 1300s have the same front tire contact patch -- wider ones don't turn. Less weight the only real solution.

The front/rear brake debate -- I never used a back brake because they lock up easily. I locked up the Busa approaching a stop sign the other day by accident. One thing no one mentioned is the rear brake itself - I think most of them are way too powerful on street bikes.

I rode an RC30 with a rear brake you virtually couldn't lock up, gave enough confidence to touch it mid-turn. I wouldn't try that on the Busa. I just sliced my rear rotor in half [lengthwise -- saved a pound or two] and hopefully can make it usable over 20 mph, my present speed limit on back brake use.