Getting better low end without going to 15/43
08-18-2010, 02:55 PM
#31
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I get the same answer, and 157, with 15/42 and 641mm tire diameter,which means there's no way I'm hitting 9500 RPM in 6th down the front straight. I think I'm more like 140 MPH. When I get it right coming off turn 15, I might be hitting 145.
I guess I'm geared too tall, but I've got other things to get right, before I worry about that, like getting off the corner faster, which means more throttle sooner and letting the bike run out to the edge of the track better. The gearing is not the problem...
I guess I'm geared too tall, but I've got other things to get right, before I worry about that, like getting off the corner faster, which means more throttle sooner and letting the bike run out to the edge of the track better. The gearing is not the problem...
08-18-2010, 03:13 PM
#32
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A stock Super Hawk will not pull 9800 rpm in 6th gear. That translates to about 177 mph, and the Hawk in stock form simply will not even come close to that. Top speed for a stock Hawk is approximately 152-155 mph, which is about 9500 rpm in 5th gear with stock gearing. 9500 in 6th gear with 15/43 gearing is about the same speed--perhaps 1 or 2 mph faster.
I don't know how one would define most usable power overall.
I don't know how one would define most usable power overall.
For 16/43 it's 167 vs 159, so that just 8 mph... And at that point the hawk will actually pull past redline in 6'th... Making it theoretically faster than both 16/41 in 5'th which is 148 and 15/43 in 6'th which is like mentioned 149... And with a usable first gear...
Last edited by Tweety; 08-18-2010 at 03:31 PM.
08-18-2010, 03:18 PM
#33
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A stock Super Hawk will not pull 9800 rpm in 6th gear. That translates to about 177 mph, and the Hawk in stock form simply will not even come close to that. Top speed for a stock Hawk is approximately 152-155 mph, which is about 9500 rpm in 5th gear with stock gearing. 9500 in 6th gear with 15/43 gearing is about the same speed--perhaps 1 or 2 mph faster.
I don't know how one would define most usable power overall.
I don't know how one would define most usable power overall.
I have dyno charts that show with 16\43 gearing the bike has a top speed of 159mph at 10.3K rpm (when it hits the rev limiter). So turning around 500-700rpm lower with 16\41 gearing is right at 155mph.
I would define the most usable power as a gearing that allows you to reach the rev limiter in 6th but is not too low as to make first gear all but unable.
Really, how is your bike in 1st with that gearing? I know with the higher gearing that throttle control in first is a real fine line between getting good drive and keeping the front wheel kind of close to the ground.
08-18-2010, 03:37 PM
#34
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It's freakin' fantastic. If you're trying to launch hard, just shift more weight up over the tank. I know you think it's too short, but really it's dandy. The only reason I am considering going up to 16/43 is because I'm due for new chain/sprockets soon and with handlebar mod, it shifts rider weight more rearward, making it that much more wheelie prone. Not an issue with clip ons though. Also 15/43 (as I've mentioned before) requires a lot less clutch to get away on a launch than stock (but then again, any lowered gearing helps there).
08-18-2010, 03:40 PM
#35
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My bike ain't stock anymore... 
But I have bounced of the revlimiter in 6'th more than once using 15/43... And that was before some of my engine mods... And I can say for sure that my bike pulls to the revlimiter in 6'th with 16/42 and I have no doubt it will do so on stock gearing either...
As my bike is now, my theoretical speed in 6'th is 178 at the limiter... In haven't actually measured it at that, but I did do 167 on radar on an airstrip about a month ago... And since I wasn't looking at the tacho, all I can say is that I was above 9500, but didn't hit the limiter... And I like the gearing on the street, so I'm happy...
But I have bounced of the revlimiter in 6'th more than once using 15/43... And that was before some of my engine mods... And I can say for sure that my bike pulls to the revlimiter in 6'th with 16/42 and I have no doubt it will do so on stock gearing either...As my bike is now, my theoretical speed in 6'th is 178 at the limiter... In haven't actually measured it at that, but I did do 167 on radar on an airstrip about a month ago... And since I wasn't looking at the tacho, all I can say is that I was above 9500, but didn't hit the limiter... And I like the gearing on the street, so I'm happy...
08-18-2010, 07:35 PM
#36
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Somebody correct me if I am wrong but doesn't raising your final drive ratio make your bike accelerate faster at any RPM by torque multiplication?
Personally I have a 15/43 setup on my bike and I like it. I can still use first gear for really tight corners and in the city with no problems. The bike had 16/43 final drive when I got it and I liked that too!
Personally I have a 15/43 setup on my bike and I like it. I can still use first gear for really tight corners and in the city with no problems. The bike had 16/43 final drive when I got it and I liked that too!
08-18-2010, 09:18 PM
#38
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It's freakin' fantastic. If you're trying to launch hard, just shift more weight up over the tank. I know you think it's too short, but really it's dandy. The only reason I am considering going up to 16/43 is because I'm due for new chain/sprockets soon and with handlebar mod, it shifts rider weight more rearward, making it that much more wheelie prone. Not an issue with clip ons though. Also 15/43 (as I've mentioned before) requires a lot less clutch to get away on a launch than stock (but then again, any lowered gearing helps there).
No matter how far up the tank I get my bike will happily flip over backwards in 1st if you give it too much throttle. Lowering the gearing would just make this problem worse.
As for needing clutch to get going, either you are going straight up or have some other issue as mine has never had an issue, even with the stock gearing on any hill that can be found in the SF Bay Area.
08-18-2010, 09:31 PM
#39
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With that lets look at you first numbers:
16\41 @ 9500 RPM gives you a on paper speed of 169. Subtract 10% and you are at 152. Most of the tests I have seen state the stock top speed is 155. So like I stated earlier, with my stock set up I was able to get to around 9800RPM (it was over 9500 and less than 10,000 rpm I can't give an exact number as I was kind of busy at the time) but the extra couple of hundred RPM put the bike right at 155 just like the tests.
The next 2 gear ratios you list have actually the right numbers but you got to them the wrong way.
Not only did you leave out tire slip but you also figured out the numbers @9500 RPM and the motor will pull to 10,300 with those gear ratios
So yes I agree that with 16\43 you top out at around 159 (which is what my dyno runs with that gearing show)
Also 15\43 will give you around 10 mph less or around 149.
I guess the problem is using a formula where as I've gone out and done the runs to get the info.
08-18-2010, 09:32 PM
#40
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None of those charts take into account the tire slip generated at those speeds. It's as simple as that.
08-18-2010, 09:35 PM
#41
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08-18-2010, 11:13 PM
#42
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I know tire slip occurs, but I'm very skeptical about it being anything like 10% at top of sixth on the VTR. Maybe on salt.
Numerous bone stock VTRs tested ran 155 mph through the speed gun. 10% tire slip would mean the surface of the tire was actually running about 170 mph. Which would mean a stock 16/41 VTR really would pull through red line in 6th. Except it doesn't.
Numerous bone stock VTRs tested ran 155 mph through the speed gun. 10% tire slip would mean the surface of the tire was actually running about 170 mph. Which would mean a stock 16/41 VTR really would pull through red line in 6th. Except it doesn't.
Now for tire slip. Is it just a coincidence that you take the "paper" top speed with a stock set up (yes the motor will pull to 9500 or a bit higher stock, look at the dyno charts, as that is where the power starts to drop off and we can agree that the motor can pull to the HP peak in 6th, right?)
which by the numbers you posted is 169mph. Then subtract 10% for tire slip and you get 152-153 or right at where the bike tested at. To get to the 155 mph mark you would need to spin just a bit faster than 9.5k
So to end up with a top speed of 155 either the motor can't even pull to the HP peak in 6th or you have tire slip. Which makes more sense?
This is also why the speedo gets more "optimistic" the faster you go.
Don't know what to tell you. With 16\43 you can bounce the motor off the rev limiter with no real problems. With 16\41 and a stock motor it runs out of steam around 500-700 rpm before that.
08-19-2010, 12:32 AM
#43
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I always assumed the 155 mph top speed reported was either obtained in 5th gear, or 6th gear power peak, reported between 8600 rpm and 8800 rpm depending on the dyno and year of bike tested. Calculated rpm at 155 in 6th (without tire slip) would be between 8700 and 8800 rpm. The 169 mph I cited would be 9500 rpm in 6th, not HP peak.
You also ignored that if you factor in the standard 10% tire slip the numbers you posted for top speed with a stock motor in 6th @ 9500rpm now comes directly in line with the 155 published top speed.
I don't know what to say about tire slip. It would vary depending on tire construction and grip, be affected by ambient temperature, road surface temperature, the material the road was surfaced with and the texture of the road surface. I think you'd need an accurate tachometer and speed gun each feeding data to a computer in real time to measure it. I don't pretend to know for sure, I just doubt it's as high as 10%.
Then I guess we are arguing theory vs practical testing. While you state you assume the rpm for top speed and also don't care about it, I have gone out and done it.
08-19-2010, 12:42 AM
#44
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08-19-2010, 10:40 AM
#45
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You are right, but if I remember correctly, You've reported your VTR has been dynoed at 112+ HP. The highest I've ever seen reported for a stock VTR is 104.8, with most all others at 98-102. Like I said, I'll take you at your word for your bike. And yeah, the whole thread is about "theory". Consider that a VTR with 10-14 fewer HP than yours might not pull 9800 rpm in 6th with stock sprockets. If one ever has, I've never heard of it.
I was figuring out gearing long before I did any motor work. I'm pretty sure I could get it to the rev limiter with 16\41 gearing now. Also it might be I had a bit more top end as the cams are a bit bigger in these early models.
08-19-2010, 02:36 PM
#46
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Bone stock my bike went beyond redline in 6'th, but never made it to the limiter... Can't say exactly where it died out though, but somewhere between 9500-10000, so around 9800 sounds feasible...
08-19-2010, 02:55 PM
#47
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At least I'm not the only one who was able to run it up like that.
08-19-2010, 04:49 PM
#48
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I understand the concept and variables. Poking around the web I found technical pages with the formula.
What I was hoping to find was something like a chart- typical sport bike experiences slip ratio of "x" at 140 mph, "y" at 150 mph etc., or at least an example of a similar bike where they collected the data and ran the equation.
I came up with jack squat.
What I was hoping to find was something like a chart- typical sport bike experiences slip ratio of "x" at 140 mph, "y" at 150 mph etc., or at least an example of a similar bike where they collected the data and ran the equation.
I came up with jack squat.
http://www.gearingcommander.com/
08-19-2010, 05:19 PM
#51
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Maybe this thread will be more on target with you.
http://www.f1technical.net/forum/viewtopic.php?f=6&t=6300&sid=2cb20c49b68f1e543f496 9213d4c1687
No offense taken.
http://www.f1technical.net/forum/viewtopic.php?f=6&t=6300&sid=2cb20c49b68f1e543f496 9213d4c1687
No offense taken.
Last edited by RWhisen; 08-19-2010 at 06:05 PM.
08-19-2010, 06:02 PM
#52
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Tire slip is very real.
08-19-2010, 08:10 PM
#53
Paul
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I thank ya'll for the help! I ordered a couple of different sprockets so that I can experiment a little bit with the different combinations. Hell, i'm just enjoying myself doing stuff to the bike so I guess we'll see which set up works best for my application.
08-19-2010, 09:16 PM
#54
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Never said it wasn't real, just want to know how real at given speeds.
If it's "10% real" on a VTR going 150 mph, what would it be for a 'Busa going 190? You'd think real enough that somebody, somewhere would have measured it and posted the results by now. Not hard to do if you've got a data logger and GPS or a speed gun. I'm surprised I can't find a single report about it on the web.
If it's "10% real" on a VTR going 150 mph, what would it be for a 'Busa going 190? You'd think real enough that somebody, somewhere would have measured it and posted the results by now. Not hard to do if you've got a data logger and GPS or a speed gun. I'm surprised I can't find a single report about it on the web.
The 10% number is just the standard constant that is used to figure out true top speed. If you looked at the site I posted, the default for tire slip is..... you guessed it 10%
You don't seem to care that when you take the numbers you posted about the top speed of a SH and then subtract 10% the numbers are basically what the posted top speed is.
I guess I've had enough of this now. Just like you couldn't believe my bike could turn more than 9500 in stock form in 6th, nothing I can write will make you believe what I am saying. So you can hunt forever for an exact number.
08-20-2010, 01:46 AM
#55
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If so it's your fault. I didn't think tire slip could be that great a factor, and yeah if it is, I wonder what it would be for faster, heavier bikes etc. Obsessed? I don't know. When you read a road test don't you like seeing the the E.T. and trap speed in hundredths of seconds and mph? Is that obsessive? Please don't take it personally, it's my nature to be skeptical about claims until I find other sources of verification.
It does feel like that unless you are given the percentage of slip down to the third decimal place you can't accept that it is actually happening. Doing the math and showing you the results were not good enough for you. So keep searching the web, I'm sure if you read it there it has to be right. I could talk a bit more of the faster and heavier bikes but you wouldn't believe me anyways, so why bother.
So for me this no longer feels like a discussion but some sort of pissing contest. If you want to think I'm just making this **** up, fine.
I do really have better things to do than to beat on this anymore.
and a PS for you,
I really don't care about E.T.s printed in the mags, in fact I never even look at those numbers as I don't drag race my bikes.
08-23-2010, 07:37 AM
#56
Paul
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I got a couple of different sprockets, so I'm going to try out some of the different "combos" (namely 15/41 and 16/43). We'll see how she goes. I live in Florida so I would like a little bit of extra low-end power, but due to the amount of long / straight roads 16/43 may prove to be better for my application. Thanks for the input. I didn't even give much thought to the idea of a lightened flywheel before. Are they pretty pricey? Is there a way to "lighten" them without ruining them?
08-23-2010, 12:08 PM
#57
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I got a couple of different sprockets, so I'm going to try out some of the different "combos" (namely 15/41 and 16/43). We'll see how she goes. I live in Florida so I would like a little bit of extra low-end power, but due to the amount of long / straight roads 16/43 may prove to be better for my application. Thanks for the input. I didn't even give much thought to the idea of a lightened flywheel before. Are they pretty pricey? Is there a way to "lighten" them without ruining them?
Well I wasn't going to get sucked back into this thread but oh well.
As for gearing, there really isn't a whole lot of difference between those two ratios. In your case it would be more how you want the bike to handle.
With 16\43 you will shorten the wheel base slightly which will make the bike turn quicker but will also make the bike a little less stable (that's why it turns quicker).
The 15\41 set up will lengthen the wheel base making it turn slower but it will be more stable, which might be better for your roads.
Lightening the flywheel is pretty simple. If you do a search, there are many threads about it. As long as you have an impact gun and a good torque wrench it should be no problem.
08-23-2010, 02:17 PM
#58
Paul
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I found the threads about lightening the flywheel. As far as what was stated earlier "Advance your exhaust cams 4 degrees". How Is this done, and what will this do? Ya'll are definately a wealth of knowledge. I've learned more in a couple of weeks then I have in years regarding the mechanics of bikes.
08-23-2010, 02:47 PM
#60
Paul
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I have done timing advances on cars (Chevy Monza and 57' Chevy) but i'm not sure it's something that I want to mess with on my bike yet. I think that between new pipes, jetting, different sprockets, and possibly lightening the flywheel, I should be set for a while. Hopefully I can find a shop in my area that will do the flywheel. I'm still a bit leary about having someone taking material off of the flywheel but I guess I could just start off small and go from there.
