Wheel lift during acceleration - Wrist Twisters
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post #1 of 50 Old 01-07-2012, 09:24 PM Thread Starter
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Wheel lift during acceleration

So this may come off as a stupid question but I'm trying to figure something out since I am a fairly new rider. In 1st gear I pretty much roll on the throttle and short shift at like 8-9k because I feel like the front wheel is going to lift and sometimes it does if I roll on too quickly. Even 2nd gear makes the front feel very light and I get that skipping feeling so I don't quite go 100% until the end of the gear. While I like the torque down low it sure feels like I can get myself in trouble pretty quickly. When I drive my friend's CBR600 I am able to rip through the gears because by the time it's making most of it's power the bike is going fast enough and the wheel always stays on the ground. What do you guys do? Are you able to go full throttle in 1st at any point all the way till redline and shift into 2nd going 100%? I'm trying to figure out if it's just in my head that the bike feels like it's going to lift or if it really will, especially during a rapid 1-2 shift. When I see guys doing power wheelies with a 1000 it seems like you really have to twist the throttle quickly and it's not going to lift unless you want it to. So will a roll on to 100% throttle into first gear be possible or do you guys go like 75-80% in first? Or is front wheel lift something I am just going to have to get used to? I'm not asking so I can jump on it tomorrow and go balls out, I more or less want to know the physics of it. BTW, I have a 2011 CB1000R which is basically the same power as most of your 919s. I think it's 124HP and 74FT LBS TQ.

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post #2 of 50 Old 01-07-2012, 09:41 PM
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Yeah try taking 25HP and 6ft-lbs offof those numbers. If I am going hard I still roll on the throttle and can take each gear to red line. I won't snap it because the front will lift with the low end torque. You just have to get use to the bike

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post #3 of 50 Old 01-07-2012, 10:08 PM
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Yeah, you have to smooth your way to red line (though there's not much reason to red line). I've gotten the front up a couple times unintentionally b/c I was gunning it while horse assin' around with my buddy and his 600rr. Once you get in second you should be able to gun it as you please with minimal lift. Ya might get off but not so much as to be scary or uncontrollable. Then again I'm still pretty fresh to my 919 so I could be blowing smoke out my ass!

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post #4 of 50 Old 01-07-2012, 10:10 PM
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Quote:
Originally Posted by Brewcrew02 View Post
Yeah, you have to smooth your way to red line (though there's not much reason to red line). I've gotten the front up a couple times unintentionally b/c I was gunning it while horse assin' around with my buddy and his 600rr. Once you get in second you should be able to gun it as you please with minimal lift. Ya might get off but not so much as to be scary or uncontrollable. Then again I'm still pretty fresh to my 919 so I could be blowing smoke out my ass!
That's good point what is the reason for you going to red line?

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post #5 of 50 Old 01-07-2012, 10:23 PM
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thats the whole point of the 9er... easy power wheelies..... jsut dont do like i did and do an awesome one infront of a cop!

ull get ust to it!

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post #6 of 50 Old 01-07-2012, 10:23 PM Thread Starter
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That's good point what is the reason for you going to red line?

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Quote:
Originally Posted by Brewcrew02 View Post
Yeah, you have to smooth your way to red line (though there's not much reason to red line). I've gotten the front up a couple times unintentionally b/c I was gunning it while horse assin' around with my buddy and his 600rr. Once you get in second you should be able to gun it as you please with minimal lift. Ya might get off but not so much as to be scary or uncontrollable. Then again I'm still pretty fresh to my 919 so I could be blowing smoke out my ass!
So short shifting at say 8-9k is the way to go for the best acceleration?

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post #7 of 50 Old 01-07-2012, 10:28 PM
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The 919 and CB1R motors were re-tuned specifically for more torque, not crazy HP. So you'll have more power down low in the RPM's; that is the nature, and IMO, the FUN of the bike(s).

At higher elevation it becomes much more difficult to loft the front wheel (I'm at ~5k). I can only do it in front gear if I snap the throttle REALLY fast at 4500-4800 RPM's. No where else really does it.

Don't think I've ever gotten the front up in 2nd with stock gearing.

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post #8 of 50 Old 01-07-2012, 11:07 PM Thread Starter
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Originally Posted by g00gl3it View Post
The 919 and CB1R motors were re-tuned specifically for more torque, not crazy HP. So you'll have more power down low in the RPM's; that is the nature, and IMO, the FUN of the bike(s).

At higher elevation it becomes much more difficult to loft the front wheel (I'm at ~5k). I can only do it in front gear if I snap the throttle REALLY fast at 4500-4800 RPM's. No where else really does it.

Don't think I've ever gotten the front up in 2nd with stock gearing.
Yea the stock gearing is pretty short, I am constantly hitting the revlimiter in 2nd an 3rd. A shiff light would be nice (its hard to see the electronic blue dash in bright sunlight, though I am able to pretty much pick up the right pitch of the engine to shift). Maybe adjust the sprockets for taller gearing until I can get used to tha. Right now I'm going through the first few gears so fast I don't even get to enjoy them. I'm thinking of doing a full exhaust with a pcIII and it would allow me to add a quickshifter. I could set the milliseconds between shifts at like 75milliseconds. Not having to work the clutch would give me more control and be able to hang on easier.

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post #9 of 50 Old 01-07-2012, 11:43 PM
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Just my two cents here.

If, as you say, you are a fairly new rider, it might be good for you to stay away from red-lining, wheelying tricks and stunts till you've got a bit more experience and a few more (safe) miles under your belt. It's a strange world where 8-9k is considered a short shift.

As witnessed by the video posted in the "mid-day digger" thread, things can turn awful foolish awful fast...

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post #10 of 50 Old 01-08-2012, 03:35 AM
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post #11 of 50 Old 01-08-2012, 05:12 AM
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As mentioned above, watch this video:

https://www.wristtwisters.com/forums/...ger-29058.html

It can all go bad pretty quickly, since you're a new(er) rider I'd take it easy for a while.

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post #12 of 50 Old 01-08-2012, 08:39 AM
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A short shift, as I understand it, is shifting before peak power is reached. Shifting a 919 at 9000 RPM is definitely not short shifting it. Worrying about short shifting is best left to the track, in my opinion. Ride within safe limits on the street, especially if you're a new rider. If you're out in the countryside doin twisties, that's another thing. Too much can go wrong on city streets to be constantly pushing the bike to its limits. Just trying to save you from a hard lesson.

A quickshifter is totally unnecessary on a street bike. Again, just my opinion. You can do a quick shift without the clutch if you're really in a hurry. Under hard acceleration, put pressure on the shifter, momentarily let up slightly on the throttle, and the bike will slip into the next gear. Then get on it hard again. Lots of guys shift this way as a matter of routine. Personally, I save it for special occasions. Lol. Either way, it's a good skill to learn, in case your clutch cable breaks and you have to get home.

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post #13 of 50 Old 01-08-2012, 09:05 AM
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Quote:
Originally Posted by Stutz View Post
go up a tooth on the countershaft sprocket.
That's why I went up a tooth. With a PCIII retune and LeoVince more open exhaust, it will still lift the front wheel in first or second, but, just not as easily as with stock gearing. When I first put on the PCIII with debaffled stock exhaust, the front lifted by accident when I went over the crown in the road at an intersection. Glad there wasn't a officer observing that intersection.

I like the fact that it will wheelie, but, I also like the fact that the higher gearing makes the accidental wheelie less probable. And, a little less rpms at highway speed isn't a bad thing, either.

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post #14 of 50 Old 01-08-2012, 09:12 AM
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I went with 17/44 (up a tooth on both) and am very happy with it.

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post #15 of 50 Old 01-08-2012, 09:22 AM Thread Starter
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Prolly the best advice is just to take it easy. I watched the mid day digger vid, that would be heart breaking and he came out of that super lucky. I mainly wanted to know the physics and it sounds like the wheel coming off the ground is just something that happens when you have a lot of torque. I never thought I would say this but I have more fun on my friend's weaker 600 for this reason. Oh well, I will just take it easy and in time this will be more fun than scary. I may look into taller gearing too, the cb1kr is just way too shortly geared for me.

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post #16 of 50 Old 01-08-2012, 09:33 AM
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Why the relatively "short gearing"? Aerodynamics. The fully faired CBR is geared to take advantage of it's better aerodynamics, while unfaired (yes, even the CB1000) bikes suffer from a case of diminishing returns as speed goes past 110 or so. The air just can't get out of the way, and drag increases to the point of making it impossible to ge much past 150 or so regardless of the amount of power produced. That said, it would be beneficial to go to a 17 tooth countershaft sprocket to help keep the front end on the road.

Roadracing teaches that regardless of where you are on the tach the power produced is a function of how much throttle you are giving it. In other words when exiting a corner you should turn the throttle just enough to maintain an optimum rear slip of ~9% which will give the best drive out while not unloading the front wheel enough to compromise steering.

The rear brake is invaluable in controlling power delivery to the rear wheel if you want to get dogmatic about holding 100% throttle, but it will benefit you to develop the instincts with the throttle to keep the front tire in contact with the road. That's called "feeling traction" and once you have the basics down you will find you will accelerate faster and more smoothly.

Aditionally, as stated in previous responses the engine really doesn't have to be wrung out all the time -- if you keep it between 6 to 8 grand that's right in the fat part of the torque curve and the most controllable region.

One last thing: I absolutely agree about the awful trend of blue lighting instruments -- they might look trick, but human eyes have several undesirable reactions to blue light that in the short term cause a general decrease in visual acuity, and in the long term can cause retinal damage. Worse, in even relatively low levels it also significantly decreases scotopic (night) vision by washing out the retina. Personally, I know that the headlights that trend more toward the 400nM end of the spectrum make seeing detail at night very difficult despite their subjective brightness. The proliferation of blue LED's used as indicators on home electronics is getting quite irritating to many people, and there is a growing movement to convince manufacturers to curtail their use of them. An article on the subject: Artificial Lighting and the Blue Light Hazard
Frankly, I would look into replacing the blue lights in the instruments with a different color such as a yellow / green (the colors the eye is most reactive to) or red, though if it's an ELD it may not be possible.

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post #17 of 50 Old 01-08-2012, 03:26 PM
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rob.... seriously is there anything you don know?

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post #18 of 50 Old 01-08-2012, 03:31 PM
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rob.... seriously is there anything you don know?

I asked Rob that exact same Q a few threads ago....lol
https://www.wristtwisters.com/forums/...tml#post478305

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post #19 of 50 Old 01-08-2012, 04:07 PM
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[QUOTE=jay313;481412]A short shift, as I understand it, is shifting before peak power is reached. Shifting a 919 at 9000 RPM is definitely not short shifting it. Worrying about short shifting is best left to the track, in my opinion.

Wrung out safely on a private road, or on a track, short shifting sometimes has to be done, just like selective over-rev is used from time to time.

Short shifting in nothing more than shifting below the RPM that gives the most advantageous driving force thrust for the next gear.
One needs to have the torque curve, the internal drive reduction ratio, the gearbox ratios, the final drive ratio, and the tire diameter, in order to be able to figure it all out.
There's a really slick XL sheet kicking around that does all the number crunching for you.
Generally, that RPM will be past peak HP.

If you shift a 919 at a tach indicated 9000 revs, it is being short shifted.
1 peak power is higher than 9000
2 as a rule, the factory tach over reads, mine is high by 300 or so revs up in the 9s.

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post #20 of 50 Old 01-08-2012, 05:40 PM
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i think youll find the more you ride...its,,,not that easy to power wheel every time with 919.....leaning foward will stop wheel lift period on 919....plus if banging gears at redline and your worried about a little wheel lift...you shouldent be riding a bike...wheel lift is what its all about if pushing a bike hard......most ask why my wheel wont lift...i smell a rat

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post #21 of 50 Old 01-08-2012, 06:15 PM
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Quote:
Originally Posted by OSUBUCKEYES View Post
So this may come off as a stupid question but I'm trying to figure something out since I am a fairly new rider. In 1st gear I pretty much roll on the throttle and short shift at like 8-9k because I feel like the front wheel is going to lift and sometimes it does if I roll on too quickly. Even 2nd gear makes the front feel very light and I get that skipping feeling so I don't quite go 100% until the end of the gear. While I like the torque down low it sure feels like I can get myself in trouble pretty quickly. When I drive my friend's CBR600 I am able to rip through the gears because by the time it's making most of it's power the bike is going fast enough and the wheel always stays on the ground. What do you guys do? Are you able to go full throttle in 1st at any point all the way till redline and shift into 2nd going 100%? I'm trying to figure out if it's just in my head that the bike feels like it's going to lift or if it really will, especially during a rapid 1-2 shift. When I see guys doing power wheelies with a 1000 it seems like you really have to twist the throttle quickly and it's not going to lift unless you want it to. So will a roll on to 100% throttle into first gear be possible or do you guys go like 75-80% in first? Or is front wheel lift something I am just going to have to get used to? I'm not asking so I can jump on it tomorrow and go balls out, I more or less want to know the physics of it. BTW, I have a 2011 CB1000R which is basically the same power as most of your 919s. I think it's 124HP and 74FT LBS TQ.
You're a fairly new rider and seem to have already habituated having it pinned all the time.
On a one litre bike no less.
I wonder how long you'll be able to ask questions.

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post #22 of 50 Old 01-08-2012, 08:07 PM
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I went from a 600 to a 1000 3 years ago. I can see your point in the 600 being "easier" to ride than the 1000. The big difference between the two is the torque and upper horsepower. If I was going through the twisties with the 600 at around 6000 rpm and cracked into the throttle, the thing just dipped in a little harder and went. Do the same thing with the 1000 and there won't be enough tire touching the ground to turn at all. That motor is making all kinds or horsepower at 8-9 grand, which is hard to control. Best advice is just to play with it when you are out and about and no one is around. If your revin' 8-9 in town, your asking for trouble. Respect the power or it will bite you in the butt.

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post #23 of 50 Old 01-08-2012, 11:14 PM Thread Starter
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I went from a 600 to a 1000 3 years ago. I can see your point in the 600 being "easier" to ride than the 1000. The big difference between the two is the torque and upper horsepower. If I was going through the twisties with the 600 at around 6000 rpm and cracked into the throttle, the thing just dipped in a little harder and went. Do the same thing with the 1000 and there won't be enough tire touching the ground to turn at all. That motor is making all kinds or horsepower at 8-9 grand, which is hard to control. Best advice is just to play with it when you are out and about and no one is around. If your revin' 8-9 in town, your asking for trouble. Respect the power or it will bite you in the butt.
I do somewhat regret not buying the 600 first. I think less torque gives you a good safety margin and in hindsight would of bought the cbr600rr I was looking at. I'm stuck with the cb1kr now and will just have to take it easy. After seeing the mid day digger video it really shows how quickly you can get in trouble and that you don't have to be driving "really crazy" to wreck. I took it out again today for a nice relaxing ride and for now I'm fine with that until I improve my skills. Thanks for the advice everyone.

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post #24 of 50 Old 01-09-2012, 07:48 AM
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Quote:
Originally Posted by OSUBUCKEYES View Post
After seeing the mid day digger video it really shows how quickly you can get in trouble and that you don't have to be driving "really crazy" to wreck.

If you don't define that example as "really crazy", please reconsider.

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post #25 of 50 Old 01-09-2012, 08:33 AM Thread Starter
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If you don't define that example as "really crazy", please reconsider.
Not getting into a debate on what is crazy. Check out youtube and you will find many riders doing much more insane things and causing themselves to wreck. The mid day digger guy was just getting a little cocky and bit it. Now doing that stuff in a school zone and city streets is completely idiotic and he is lucky he didn't kill a child. I'm not going to sit here and defend myself, I have acknowledged the advice given here, and taken it to heart.

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post #26 of 50 Old 01-09-2012, 08:44 AM
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good definition...

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post #27 of 50 Old 01-09-2012, 09:00 AM
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Quote:
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Not getting into a debate on what is crazy. Check out youtube and you will find many riders doing much more insane things and causing themselves to wreck. The mid day digger guy was just getting a little cocky and bit it. Now doing that stuff in a school zone and city streets is completely idiotic and he is lucky he didn't kill a child. I'm not going to sit here and defend myself, I have acknowledged the advice given here, and taken it to heart.
Generally, the right hand is what gets one into trouble.
I mean the twist and the lever, not just the twist.
Obviously, the right hand can only do what brain says to do, but I think relating it to the right hand is more insightful.
Try to develop the lever expertise first, and get it to as high a level as you can as soon as you can.
Twist basics are good enough now.

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post #28 of 50 Old 01-09-2012, 01:29 PM
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Quote:
Originally Posted by OSUBUCKEYES View Post
I do somewhat regret not buying the 600 first. I think less torque gives you a good safety margin and in hindsight would of bought the cbr600rr I was looking at. I'm stuck with the cb1kr now and will just have to take it easy. After seeing the mid day digger video it really shows how quickly you can get in trouble and that you don't have to be driving "really crazy" to wreck. I took it out again today for a nice relaxing ride and for now I'm fine with that until I improve my skills. Thanks for the advice everyone.
Since you feel 'stuck' with a CB1R, I'll take it off your hands for my 919. It's a pretty sweet setup, straight trade. It'll drop you 20HP or so and should be more in your realm.


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post #29 of 50 Old 01-09-2012, 02:05 PM
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Since you feel 'stuck' with a CB1R, I'll take it off your hands for my 919.
...always thinking of others. What a sweetheart!

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post #30 of 50 Old 01-09-2012, 02:26 PM
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...always thinking of others. What a sweetheart!

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post #31 of 50 Old 01-09-2012, 02:37 PM
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I think the shift point calculator and gearing calculator would be worthy additions to the Drop Box.
Agreed ?

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post #32 of 50 Old 01-09-2012, 02:38 PM
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I think the shift point calculator and gearing calculator would be worthy additions to the Drop Box.
Agreed ?
Most definitely!

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post #33 of 50 Old 01-09-2012, 04:46 PM
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Most definitely!
Check out new Drop Box Folder called "Calculators"

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post #34 of 50 Old 01-09-2012, 04:50 PM
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Wrung out safely on a private road, or on a track, short shifting sometimes has to be done, just like selective over-rev is used from time to time.

Short shifting in nothing more than shifting below the RPM that gives the most advantageous driving force thrust for the next gear.
One needs to have the torque curve, the internal drive reduction ratio, the gearbox ratios, the final drive ratio, and the tire diameter, in order to be able to figure it all out.
There's a really slick XL sheet kicking around that does all the number crunching for you.
Generally, that RPM will be past peak HP.

If you shift a 919 at a tach indicated 9000 revs, it is being short shifted.
1 peak power is higher than 9000
2 as a rule, the factory tach over reads, mine is high by 300 or so revs up in the 9s.
C'mon, bro. You're getting way too technical here. Lol. Essentially, with the 919 redline at 9500, and probably off by 300 at the upper end as you note, you're saying that every shift under indicated redline is a short shift. If every shift is a short shift, it pretty much renders the term useless. Let's go with the useable street side of things, not what is or isn't right for the track.

As a practical matter on the street, if you're hitting 9000 indicated rpm, you're pretty darn close to peak HP on a shift. For the average street rider, I'd call a short shift anything under 8000 or so. But that's just my working definition. Then again, I typically shift around 4000 rpm on a simple ride around the city. Am I disqualified from the discussion now? lol.

Glad you took the advice to heart, OSU. Lots of long-time, experienced riders here. Still learning from them myself.

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post #35 of 50 Old 01-09-2012, 05:16 PM
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C'mon, bro. You're getting way too technical here. Lol. Essentially, with the 919 redline at 9500, and probably off by 300 at the upper end as you note, you're saying that every shift under indicated redline is a short shift. If every shift is a short shift, it pretty much renders the term useless. Let's go with the useable street side of things, not what is or isn't right for the track.

As a practical matter on the street, if you're hitting 9000 indicated rpm, you're pretty darn close to peak HP on a shift. For the average street rider, I'd call a short shift anything under 8000 or so. But that's just my working definition. Then again, I typically shift around 4000 rpm on a simple ride around the city. Am I disqualified from the discussion now? lol.

Glad you took the advice to heart, OSU. Lots of long-time, experienced riders here. Still learning from them myself.
Revised shift points gave me 200 more RPMs at the end of the main straight during track days.
Proper shift points will net more time that actual shifting technique ever will.

On the street, I short shift about 99 % of the time.
Part throttle mid RPMs is where is spends most of the time, especially when my dear sweet wife is on the back.
I'd say routine road riding for me is mostly below 6000 and no more than half throttle.

So, as you can see, I do both, and have protocols for each.
Which is what you'd expect, right ?

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post #36 of 50 Old 01-11-2012, 03:45 PM
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Right on.

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post #37 of 50 Old 01-11-2012, 04:45 PM
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Friend of mine with an SV650 kept having an issue of the front tire coming off the ground when he exits turns. It made no sense to me then I asked him a simple question.

How smooth are you on the throttle? Turns out he would go from 20% throttle mid turn to wacking it 100% open as fast as he could.

Well durrrrr

Makes me wonder about the OPs throttle control.
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post #38 of 50 Old 01-11-2012, 05:18 PM
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Originally Posted by jeffie7 View Post
Friend of mine with an SV650 kept having an issue of the front tire coming off the ground when he exits turns. It made no sense to me then I asked him a simple question.

How smooth are you on the throttle? Turns out he would go from 20% throttle mid turn to wacking it 100% open as fast as he could.

Well durrrrr

Makes me wonder about the OPs throttle control.
SV is unlinked, is it not ?
If so, depending how it's sprung and geared, it could be squatting.
I had a huge squat problem with the 919.
It was so bad you could feel the seat going down.

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post #39 of 50 Old 01-11-2012, 05:30 PM
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Not sure, all I know is I could come out of turns faster then him without pulling the front up.......
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post #40 of 50 Old 01-11-2012, 05:55 PM
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Not sure, all I know is I could come out of turns faster then him without pulling the front up.......
Your buddy sounds like he can ride...give him your bike let him give it a go

dont need a bike to ride the fast lane
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