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Discussion Starter · #1 ·
To all you LSR guys, what do you feel the optimal shift point is for maximum straight-line launch up to top speed?
FYI I have not raised my rev limiter from stock.
Reason I ask is because I have another match-up with that turbo Lamborghini coming up this Sunday and I've been practicing 2nd gear roll-on's to top-speed. QS at the 12K mark seems to work best, what are your thoughts?
BTW I've found that I have to drag the rear brake a bit when rolling on through 2nd gear to keep the front down, a technique used in MotoGP by some for wheelie control. I've never tried it until now but I definitely need it for this exercise.
 

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In the lower gears the H2 makes enough power to loft the front wheel at almost any revs and you can't use 100% throttle so the shift point for straight line racing isn't critical. It's more a case of finding the maximum throttle it will take as it gathers speed without it wheelying, I usually shift at around 10,000rpm. In fourth and fifth I aim for peak power, 12,000rpm on my bike.
 

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As close as you can get to the peak RPM limiter, without touching it.

Since the H2's power does not 'fall off' like some bikes, by revving it higher, the engine RPM drops into a higher place in the curve that has more power AFTER the shift - which helps accelerate the bike quicker than if you fell lower in the power curve by short-shifting.

BTW, you are missing out on a pile of untapped performance by leaving your rev limiter stock. That said, your bike needs to be properly tuned in the high revs if you change your peak limiter.

Brock
Brocks Performance
 

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As close as you can get to the peak RPM limiter, without touching it.

Since the H2's power does not 'fall off' like some bikes, by revving it higher, the engine RPM drops into a higher place in the curve that has more power AFTER the shift - which helps accelerate the bike quicker than if you fell lower in the power curve by short-shifting.

BTW, you are missing out on a pile of untapped performance by leaving your rev limiter stock. That said, your bike needs to be properly tuned in the high revs if you change your peak limiter.

Brock
Brocks Performance

Brock,

He's running Stage 3 gears and an IC. Which is probably why he's around 13,200rpm. With the IC, power doesn't really climb anymore after 12,500 -13000 depending on timing, but holds steady to redline due to new airflow restrictions at high rpm.

For LSR, I'm going with Brock's recommendation of shifting as close to redline as possible.

For Track riding, shifting at peak torque, which is usually around 12,000rpm or a little past is optimal.
 

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Normally one wants to shift so that when you hit the next gear you are in the meat of the power so you can accelerate with as little effort as possible, but it seems with the H2 you are always in the meat of the power. So it seems that the thing to do is find a point where the bike is not going to wheelie hopelessly, or spin up the rear tire. Hmmm I am going to have to learn something new. Maybe I can find a sweet spot where the front lifts 6 inches and just hangs.
 

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Brock,

He's running Stage 3 gears and an IC. Which is probably why he's around 13,200rpm. With the IC, power doesn't really climb anymore after 12,500 -13000 depending on timing, but holds steady to redline due to new airflow restrictions at high rpm.

For LSR, I'm going with Brock's recommendation of shifting as close to redline as possible.

For Track riding, shifting at peak torque, which is usually around 12,000rpm or a little past is optimal.
Turbo329,

Great point! For the stage 3 gears, we would test shift points at the drag strip and measure back-half ET to see if the 'nosing over' at high revs would offset the gains of a higher rpm after the gear drop.

FYI: Most of today's normally aspirated sportbikes will nose over in the high revs on the dyno...but ram air prevents this from happening at the track, so a higher shift point is the fastest option.

Brock
Brocks Performance
 

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@Turbo329

I wonder if a better design on the cooling heatsink in the plenum would help. It seems like someone first came up with the big block heatsink, a year ago, and stuck it in the middle of the plenum to cool it down because that was what he had to shove in there. No one has really challenged the original design. We know it works, I wonder if there would be something more efficient that wasnt a giant block in the way of the airflow to limit it at high RPM's. Think a thinner more linear heatsink across the face of it, or multiple of them on the exterior walls of the plenum. Would the air need to cross them to keep the temp down.

Just thoughts about the limiting factors of the original design.

NOLA
 

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Nola nothing wrong with the core size on the billet IC's, its not a restriction, it flows so well the fins were needed to get even distribution across the core otherwise the air just flowed through a small part of the core , the power drop over 12000rpm seems to effect some bikes and not others and i am pretty sure the IC is not the common factor
I hear comments about the compressor getting out of efficiant speed range and that cams are too small and bigger are needed, seems more questions than answers so far
RG's comment about tuning the power drop out would indicate its not a mechanical cause but setup and tune
 

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My bike uses stock wheelbase for LSR, hence my earlier comment that there is no gain for me in shifting at peak power in the lower gears where you cannot use 100% throttle.

That's why I said that I don't use peak power shifting until it's in fourth gear so that, as Brock explained, it drops into fifth at the optimum revs.

In the lower gears it's about judgement of power, which is throttle position and revs, against available grip and keeping the front down. I run LSR with TC off.

Even in fourth the front wheel is trying to lift and I don't always get on 100% throttle but fourth is important because you're building the revs up for fifth and then sixth where you can.

In a nutshell: 1st, 2nd and 3rd there's no advantage to peak power shifting. 4th and 5th there is. I say this based on three seasons experience of running the H2 in LSR competition.

One more point: If you're just giving it 100% throttle through all the gears and letting the TC intervene then it's a different argument - but you WILL be slower than a rider who has good throttle control.
 

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In the lower gears the H2 makes enough power to loft the front wheel at almost any revs and you can't use 100% throttle so the shift point for straight line racing isn't critical. It's more a case of finding the maximum throttle it will take as it gathers speed without it wheelying, I usually shift at around 10,000rpm. In fourth and fifth I aim for peak power, 12,000rpm on my bike.
I'm no drag racer or straight line racer but what more needs to be said than this ?
When it's making more power than you are able to use its time to change gear regardless of RPM , with the H2s power and short wheelbase wheelie's are inevitable if you try and use all the revs in the lower gears .
 

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Discussion Starter · #11 ·
When it's making more power than you are able to use its time to change gear regardless of RPM , with the H2s power and short wheelbase wheelie's are inevitable if you try and use all the revs in the lower gears .
yeah it's a challenge to get up into 4th gear with max acceleration, especially when your bike is close to 300hp and stock wheel base for sure. As I mentioned in my op I've been practicing with a touch of rear-brake drag in 2nd gear just as the front starts to come up, this allows me to be right on the edge without having to back off the throttle.

One other thing I didn't mention; on a couple of my 2nd-gear roll-on practice runs I had a bit of trouble with steering, by the time I have shifted into 3rd my bike is sometimes leaning to the right, not always, sometimes I keep it in a straight line, but the few times it does start to turn it's to the right. I'm trying to narrow down what I'm doing to make this happen. I guess my first thought is I'm pulling the right handlebar in as twisting the throttle, keeping in mind that I'm laying on the gas tank and my elbows are down close to my knees. Any thoughts?
 

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Ignition timing is a big deal with these bikes and how power is delivered. I'm working on a sweet setup right now where 1st thru 4th gear use stock ignition timing and 5th and 6th gear use the hotter timing. With stock ignition timing I have no problem getting to full throttle at the top of 2nd gear even with the stage 2 gears. I can run that through fourth and then BANG 5th and 6th bring the heat and power wheelie about 6 inches off the ground at a buck seventy.
 

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Is using the rear brake influencing the balance of the bike ? i know i prefer GP shift pattern on the LSR bikes as the push in higher gears when in the race crouch does less to unbalance the bike than the pull

My preferred shift point on the previous LSR bikes has been after peak torque but these are a little different , i like Brocks comment about taking it to a drag strip where you can get very definite data about how any particular rpm shift point effects the run
 

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One other thing I didn't mention; on a couple of my 2nd-gear roll-on practice runs I had a bit of trouble with steering, by the time I have shifted into 3rd my bike is sometimes leaning to the right, not always, sometimes I keep it in a straight line, but the few times it does start to turn it's to the right. I'm trying to narrow down what I'm doing to make this happen. I guess my first thought is I'm pulling the right handlebar in as twisting the throttle, keeping in mind that I'm laying on the gas tank and my elbows are down close to my knees. Any thoughts?
I mostly go where I'm aiming when I'm fully on the power or on one wheel, however sometimes I drift right but I put it down to subconsciously not wanting to drift into the verge ( UK drive / ride on the left ) but with that theory you would go left . It could well be pulling on the throttle , when the front tyre first lifts the wheel often turns to the right .
 

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One other thing I didn't mention; on a couple of my 2nd-gear roll-on practice runs I had a bit of trouble with steering, by the time I have shifted into 3rd my bike is sometimes leaning to the right, not always, sometimes I keep it in a straight line, but the few times it does start to turn it's to the right. I'm trying to narrow down what I'm doing to make this happen. I guess my first thought is I'm pulling the right handlebar in as twisting the throttle, keeping in mind that I'm laying on the gas tank and my elbows are down close to my knees. Any thoughts?
Well first of all pulling the right bar will make you go left. If you are pulling on the bar, maybe subconsciously you are compensating with your body hanging off to the right.
If I were to guess, my first thought would be your body position is off to the right or you are weighting the right peg. Or maybe the front wheel is lifting enough and the rear is driving left or right.
Either way you would probably instinctively compensate.
 

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yeah it's a challenge to get up into 4th gear with max acceleration, especially when your bike is close to 300hp and stock wheel base for sure. As I mentioned in my op I've been practicing with a touch of rear-brake drag in 2nd gear just as the front starts to come up, this allows me to be right on the edge without having to back off the throttle.

One other thing I didn't mention; on a couple of my 2nd-gear roll-on practice runs I had a bit of trouble with steering, by the time I have shifted into 3rd my bike is sometimes leaning to the right, not always, sometimes I keep it in a straight line, but the few times it does start to turn it's to the right. I'm trying to narrow down what I'm doing to make this happen. I guess my first thought is I'm pulling the right handlebar in as twisting the throttle, keeping in mind that I'm laying on the gas tank and my elbows are down close to my knees. Any thoughts?
Are you not yet running the SATO GP Shift? If not, why the **** not? lol
 

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Ignition timing is a big deal with these bikes and how power is delivered. I'm working on a sweet setup right now where 1st thru 4th gear use stock ignition timing and 5th and 6th gear use the hotter timing. With stock ignition timing I have no problem getting to full throttle at the top of 2nd gear even with the stage 2 gears. I can run that through fourth and then BANG 5th and 6th bring the heat and power wheelie about 6 inches off the ground at a buck seventy.
That is great for a guy of your size!

I'm 135 lbs and not quite there yet which i assume is the rich afr you are referring to.
 

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yeah it's a challenge to get up into 4th gear with max acceleration, especially when your bike is close to 300hp and stock wheel base for sure. As I mentioned in my op I've been practicing with a touch of rear-brake drag in 2nd gear just as the front starts to come up, this allows me to be right on the edge without having to back off the throttle.

One other thing I didn't mention; on a couple of my 2nd-gear roll-on practice runs I had a bit of trouble with steering, by the time I have shifted into 3rd my bike is sometimes leaning to the right, not always, sometimes I keep it in a straight line, but the few times it does start to turn it's to the right. I'm trying to narrow down what I'm doing to make this happen. I guess my first thought is I'm pulling the right handlebar in as twisting the throttle, keeping in mind that I'm laying on the gas tank and my elbows are down close to my knees. Any thoughts?
A couple of thoughts. Firstly dragging the rear brake versus modulating the throttle position. A touch of rear brake does work to recover a developing wheely, as opposed to shutting the throttle. It was a technique that was more necessary with CV carburettors because the lag for the slides to drop when you shut off and then the time it took for them to rise again when you opened the throttle. Because of this lag we used to keep it wide open and simply fan the clutch to change up when running quarter miles, it worked too. With fuel injection it makes little difference. As a technique it's a case of whatever works for you.

Secondly, your "leaning to the right" comment. I haven't experienced this myself but something similar doing LSR. I find I have to begin a run with my throttle hand in a position which gives me a comfortable grip when on 100% throttle, in other words a straight wrist, because once under full acceleration it's almost impossible to adjust your grip. I wonder if this is your problem, having your throttle hand in the wrong position? I now begin with my right wrist above the throttle so that it straightens into a natural position as I open her up. Hard to describe but I hope you see what I'm getting at.
 

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Discussion Starter · #19 ·
maybe the front wheel is lifting enough and the rear is driving left or right.
Yes this is definitely a factor. After my last post I did some more practice runs and even with me milking it the front was coming up or getting real light in every gear. Steering straight becomes a challenge. You could be right about the rear being a factor here.

Are you not yet running the SATO GP Shift? If not, why the **** not?
No I chose not to go with GP shift because I have 3 bikes with I use regularly. My zx-10r racebike was GP shift and when I would go back-n-forth onto the different bikes it would screw me up, I was shifting the wrong way sometimes on the track whether I was on the zx10 or the H2, so I just decided to stay standard shift and it hasn't slowed me down at all. My H2 does have QS & auto blip though.

I find I have to begin a run with my throttle hand in a position which gives me a comfortable grip when on 100% throttle, in other words a straight wrist, because once under full acceleration it's almost impossible to adjust your grip. I wonder if this is your problem, having your throttle hand in the wrong position? I now begin with my right wrist above the throttle so that it straightens into a natural position as I open her up. .
Yes that is probably a method I should take a look at. If my wrist was rolled forward over the top of the throttle when it is closed then by the time I'm WOT my wrist will be in more of a natural position.

Keep in mind that some of these little things may make a difference, but bottle line my bike is nearly 300hp and is violently spinning/slipping the wheel inside the tire every time I ride it so as long as she stays at the stock wheel base I think it's going to be somewhat unpredictable at times.

On Saturday I did a couple more test roll-on's and this time I recorded it. I will post up one of those clips for you guys to take a look at and see if you have any thoughts to share.
 

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Discussion Starter · #20 ·
Video

Saturday I did a few more 2nd-gear roll-on's, here is a 1 min. video that shows 4 passes.

In the 1st one you will see the front climb up in 3rd gear as I'm trying to find that "milking the throttle" point but was just a touch too aggressive, and for this one I was dragging the rear brake in 2nd but not 3rd.

There are 3 more passes that are pretty solid, the final one I think was my best.
Keep in mind I'm a roadracer not a drag guy. Your thoughts are welcome.

 
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