Author Topic: TOP SPEED (Read 17708 times) Tweet

BiggerDanno · « **Reply #25 on:** November 20, 2004, 04:33:09 PM »

Quote from: Geri

My own bike =193mph on the limiter, proven by the fact that it went 180mph dead through the traps on 17/43, fitted with an Avon ST though, which may be smaller than the BT56J, but I dunno if that is worth 3mph. Also the limiters must have some variations bike-to-bike, so I'll not argue with ya

Are you trying to say that you are on the limiter at 180 with 17/43 gearing?

The difference between 17/40 and 17/43 speed is only 4 mph, not 13 as you seem to imply. Theoretcial top with 17/43 is 187, with 17/40 = 201. If you are hitting the limiter at 180 with 17/43 or at 193 with stock gearing, something is wrong with your bike. If it is a restricted bike, then it will top at 186 with stock gearing.

busarush · « **Reply #26 on:** November 20, 2004, 04:43:51 PM »

Geri, are you quoting INDICATED speeds or GPS? HUGE difference as spelled out earlier in this post.

Pete · « **Reply #27 on:** November 20, 2004, 04:50:49 PM »

Nothing wrong with my bike (until I started building my turbo that is

)

On my first ever turn at flyers I had no idea what to expect, so I fitted 17/43 gearing. Big mistake, I kept going though the traps at 180mph dead. I realised that I was on the limiter and then put it to standard, bingo 193mph. A while later I got to wondering if I had gone for higher than stock gearing whether i would have gotten a higher speed, so I used Dognosh's gearing calculator to work out if I was on the limiter at 17/40. Here is the result:

First I knew the gearing was 17/43, and the speed on the limiter was 180mph from my timing ticket, so assuming that the rev limit was 10,600rpm I set the tyre diamete to a value that gave me a top speed in 6th of 180mph (the rev limit might be different to 10,600 but for these purposes it doesn't matter so long as I don't change anything but the gearing, some say it is 10,800 that may be true but then I would have simply reduced the tyre radius to get the 180mph correct. Here is the result for 17/43:

Now I change the gearing to 17/40, and sure enough, bang on 193mph, what my ticket said.

This proves that I was on the limiter in top on 17/40 doing 193mph. It also shows the difference between 17/43 and 17/40 to be 13mph.

Geri

Pete · « **Reply #28 on:** November 20, 2004, 04:52:20 PM »

Quote from: busarush

Geri, are you quoting INDICATED speeds or GPS? HUGE difference as spelled out earlier in this post.

Timing traps at a flyer meeting

Steve A · « **Reply #29 on:** November 20, 2004, 04:57:04 PM »

Mile and a half distance ??

busarush · « **Reply #30 on:** November 20, 2004, 04:58:24 PM »

So you're saying you did this run with a Turbo or stock bike. I'm confused.

Pete · « **Reply #31 on:** November 20, 2004, 05:00:41 PM »

Quote from: busarush

So you're saying you did this run with a Turbo or stock bike. I'm confused.

Sorry busarush, I'm still working on the turbo build. This was on my bog stock-engined bike, small airbox mod, Akropovik exhaust, TRE, pair valve removed, std ride height, no mirrors or numberplate.

Steve: about 1.5 miles run-up yes

DaveO · « **Reply #32 on:** November 20, 2004, 05:15:50 PM »

I can see 193 on a piped/tuned stock engine busa in 1.5 miles...ridden/setup well.

The main reason that a "stock" Busa cannot pull redline in top is the POWER CURVE. A stock Busa makes peak power at 9800 RPM...and falls off dramatically to it's 10800 limiter, usually losing about 10 hp.

So to get maximum speed out of a "stock" Busa you need to gear it for higher top speed...so it can hit it's peak power..I believe that is what Scott did(smart bugger).

As for top speed on stock gearing....it totally depends on rear tire circumference. Normal is close to 200....I hit the limiter at 201(GPS) on my bike during a test session with 17/39 gear.

With 18/40 I have pulled OVER 215 @ Maxton....with an ECM I modified....in a mile.

Dave

busarush · « **Reply #33 on:** November 20, 2004, 05:55:38 PM »

Geri, at what altitude did you do your 193 with 17/40?

Pete · « **Reply #34 on:** November 21, 2004, 02:56:19 AM »

Quote from: busarush

Geri, at what altitude did you do your 193 with 17/40?

Sea level pretty much, since the airfield is the coast

Wolf · « **Reply #35 on:** November 21, 2004, 07:47:30 AM »

Quote from: BiggerDanno

Mine will do 194 at sea level

Mine did 194 as well on GPS when it was stock (TRE). Altimeter 30.30 and 52 degrees F at sealevel.

Wolf

BiggerDanno · « **Reply #36 on:** November 21, 2004, 10:05:30 AM »

Geri, since your bike is not quite stock, I can believe that you hit the limiter, but what I don't understand is why it would hit it at 193 with stock gearing. Since you are calculating it from hitting the limiter at 180 with 17/43 gearing I must assume there is something wrong in the numbers.
The only variable would be tire circumference which you adjusted. Try the same thing on the one below and see if it shows the same speed.
Try this calculator, which shows stock gearing speed to be 201 vs 17/43 = 187. http://home.cfl.rr.com/redbusa/GearSpeedCalc/index.html

Pete · « **Reply #37 on:** November 21, 2004, 12:58:29 PM »

Set the tyre circumference to 74.2 and my figures are correct. It works out as 17/43 = 180mph and 17/40 = 193mph. We weren't getting any decimals back so it isn't exact, also we must account for variance in tyre scrub but it figures out right to within 1mph.

I have since run faster on the same engine with more tuning. 198.001 last meet and 200.2 the prvious (with a decent tailwind). This is with PC2 and mapping, BMC race filter, lowered till it was almost touching the deck , showing 175bhp at the wheel (our 175bhp is more like 170 over there as I understand). I was 4th with 198mph and there were 13 stock-engined busas over 193 at the last meeting.

oilheadron · « **Reply #38 on:** November 21, 2004, 03:17:12 PM »

Geri by tire scrub I assume you mean rear tire slippage due to drive forces. It IS present at those speeds. That would mean of course that even if the tire circumference you plug in happens to be exactly correct at top speed (considering the very slight tire diameter growth) there is still a discrepancy due to slippage. This means that the engine rpms are slightly higher at any given mph than paper calcs would suggest (or conversely, of course, that the bike will encounter the rev limiter at slightly slower speeds than calculated). We've had this argument on the board before, and some stubborn folks just can't or won't grasp it

, but it is a scientific FACT, has been proven a million times with precise bike telemetry, and your results are indirect proof of the same.

DaveO · « **Reply #39 on:** November 21, 2004, 03:43:10 PM »

Geri,

74" tire circumference sounds a little small to me. My usual on a fresh tire(depending on type) is ~76".

Oihhead,
I too was curious about how much slip was occuring at Maxton on my bike. My estimates were way high...In actuality my tire slip vs real was almost zero....prob due to growth offsetting the slip.Obviously there is good traction....well worn concrete!!!

I.E. My datalogger shows my terminal speed at 213.5@11000 rpm.....and Maxton's timing lights had me at 212.7xxxmph...The correlation between my datalogger, my shiftlight and the timing lights was scary accurate...when their lights caught my bike with consistant entry/exit speeds..

FWIW...I have checked the accuracy of my light/datalogger rpm with a precision freq counter....they are within 20rpm.

Dave

oilheadron · « **Reply #40 on:** November 21, 2004, 04:38:37 PM »

That definitely is some good traction. My slippage WAGPOOMA (wild-ass guess pulled out of my ass) was about 1% but you're seeing less than half that.

Edit: Wait a minute, you're seeing less than .5% net discrepancy, but the slippage could still be relatively high depending on the degree of tire growth, right?

We need to figure out a way (almost certainly done a long time ago by somebody at some level) to take pics of the rear tire at top speed and accurately determine the growth.

DaveO, did you see the Shiftpoints article in the Feb./04 Sport Rider??

DaveO · « **Reply #41 on:** November 21, 2004, 05:22:18 PM »

oilheadron,

The accuracy was usually within one mph....which as you stated is .5%...Like I said"scary accurate". I did spend most of the season correcting my shiftlight, and datalogger to be this accurate.

I saw(and copied) the shiftpoint plots....we use similiar on the 1K SS team...I.E. "angular velocity" charts.

At the time (April 04) my Busa did not benefit from using the SR plot...since my bike made peak power @ redline....HOWEVER now that it revs higher...I should go back and replot the shifts...they are VERY critical at Maxton...esp the 5-6th shift.

Dave

Pete · « **Reply #42 on:** November 21, 2004, 05:36:27 PM »

Quote from: DaveO

Geri,

74" tire circumference sounds a little small to me. My usual on a fresh tire(depending on type) is ~76".

Dave

I only changed the tyre circumference to get the speed on the program correct as recorded by the timing gear on that gearing, in order to compare it to the new recorded top speed on the stock gearing, I haven't a clue what the actual tyre circumference was, just adjusted it to make the known numbers (gearing&mph) line up

We have had long and hard debates over on 200mph.org regarding tyre growth and slippage at speed.

Geri

oilheadron · « **Reply #43 on:** November 21, 2004, 05:43:14 PM »

Quote

1K SS team

WAZZAT??

oilheadron · « **Reply #44 on:** November 21, 2004, 05:59:35 PM »

Quote

they are VERY critical at Maxton...esp the 5-6th shift.

That's very interesting that you mention that because with a stock-motor/trans Busa that's usually the only shift that you DON'T take as close to the limiter as possible. As you obviously know.

DaveO · « **Reply #45 on:** November 21, 2004, 09:53:34 PM »

Geri,

I have massaged the circumference before to match the speed....thought I was adjusting for tire slip. It wasn't UNTIL I had the datalogger setup and tested for accuracy that I found discrepencies with the timing lights in the traps...at that time I THOUGHT it was tire slip..

If it wasn't for the datalogger showing me what ACTUALLY is occuring....As anyone who runs topends knows...you really can't keep an eye on your tach/speedo etc very well.

Oilhead,

1K SS team.....Suzuki 1000 supersport team that I worked with this season. Also helped Vince W. with his 600 SS effort. Dustin ended up 3rd in points...Brock was 5th I believe. BOTH Dustin and Chip broke into the 8's at Gville last round....gearing/setup/and rider ability were crucial...

On the 5-6th shift...my bike likes to be overreved to allow it to fall HIGHER in the power curve into 6th gear...mine makes peak power ~11k...On a stocker it is different.....

Dave

oilheadron · « **Reply #46 on:** November 21, 2004, 10:13:36 PM »

Right. That's why I said what I did about a stock motor (implying a "stockish" state of tune).

Do you have a good feel for how much tire growth you're getting? I bet the bike tire manufacturers know a great deal about it whether they'd care to divulge that info or not.

DaveO · « **Reply #47 on:** November 21, 2004, 11:38:08 PM »

oilhead,

I do not have a accurate idea of how much growth is occuring at the 3000rpm+ my rear wheel is spinning. The growth for a slick, or MCR2 is substantial I am sure. IMO the growth for a stiff sidewall tire like the Battleax 014 I use is prob much less than the MCR2.

I honestly don't think the growth (on the 014)is that much...since my tire shows a good pattern of "migrating" the rubber radially around the circumference after a 210+ pass...which tells me it is sticking very well. I am sure there is some...but in my case it appears to offset the growth almost perfectly.

I would speculate that not all bikes/busa's are hooking as well as mine,(meaning they ARE slipping).....esp from the performances I have seen from other bikes...with more power...going slower than mine.

If you can't put it to the ground.....

Dave

Twisted · « **Reply #48 on:** November 22, 2004, 01:16:45 AM »

in 1999 one of the US mag(cycle world?) doods did 192 with a 10mph tailwind on a copper...

Busa@11K · « **Reply #49 on:** November 22, 2004, 07:22:22 PM »

Quote from: $$$

in 1999 one of the US mag(cycle world?) doods did 192 with a 10mph tailwind on a copper...

I believe it was Cycle World that measured an actual 194 on a stock 99 Busa ... no tailwind on that one. You're thinking of the 200+ mph recorded in the UK I think had a tail wind helping them out.

Also, I believe the Busa is in the Guinness Book of World Records as doing 194 bone stock, and holding the "fastest production motorcycle" category.

News:

Author Topic: TOP SPEED (Read 17708 times) Tweet