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Discussion Starter · #1 · (Edited)
My H2 has the earlier version of the Guhl flash which retains the 13,000 rpm limit.

Question: the dyno curve rolls off after 12,000 rpm. Is this a function of the ECU imposing a soft limit to revs or does anyone know of another reason?

I would be quite happy for it to continue climbing to 13,000 rpm, it would give me another 15-20 bhp.
 

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My H2 has the earlier version of the Guhl flash which retains the 13,000 rpm limit.

Question: the dyno curve rolls off after 12,000 rpm. Is this a function of the ECU imposing a soft limit to revs or does anyone know of another reason?

I would be quite happy for it to continue climbing to 13,000 rpm, it would give me another 15-20 bhp.

No it's not the soft rev limiter. That should only be set a few rpm before the hard limiter. When you see the power drop off after 12.5 or so that is likely related to the cam profile. Hence the reason why I think it's pretty much useless to rev over 14,000rpm. I usually shift at 13,000rpm and only wind out 6th if I have enough room.

You could play with cams and move the power farther up the rpm range but that 10-15hp you'd gain would cost you some acceleration in the lower rpm range.
 

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The cams don't seem necessarily to force power dropoff past 12,000 or 12,500, as this example dyno from Brock does not drop off there:



Maybe something else then in BobC's case?
 

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The cams don't seem necessarily to force power dropoff past 12,000 or 12,500, as this example dyno from Brock does not drop off there:



Maybe something else then in BobC's case?
It's not so much that power drops off. The torque curve becomes flat after around 11.5k.
 

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Discussion Starter · #5 · (Edited)
It's not so much that power drops off. The torque curve becomes flat after around 11.5k.
This is the torque graph, it more or less follows the power curve at the drop off point, quite flat from 9 to 12k.

The main difference between my bike and the Brock's example is the Guhl Stage 2 flash and the oxygenated race fuel. (Mine is running an Akrapovic full system and DNA filter) Perhaps I need to send my ECU off again for the latest updates.
 

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It's honestly hard to dyno the H2. I have seen power drops of 30whp because of the tire, and yours looks similar to what was happening with mine. Had to strap it down tighter to get the wheel spin to stop. It's either that, or something is causing the bike to pull timing, or you have a boost leak.
 
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Discussion Starter · #7 · (Edited)
It's honestly hard to dyno the H2. I have seen power drops of 30whp because of the tire, and yours looks similar to what was happening with mine. Had to strap it down tighter to get the wheel spin to stop. It's either that, or something is causing the bike to pull timing, or you have a boost leak.
This answer I like. My dyno operator is very experienced but when I asked him about strapping down and slippage he said he could tell if it was spinning up. Maybe he can't?

I'm going to investigate further. Got another session booked before our records meeting next month. I bought an O2 eliminator, not listed for the H2 but the lambda sensor used is the same part number 21176-0789 as the ZX10R, I want to remove the sensor, trying to improve the low down throttle feel. Anyone done this?
 

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There was no real change in torque from 10,500 to 11,500, pretty much flat-lined, so I don't know why to assume that at past that it dropped off from uncontrolled wheelspin. It's also so smooth at the dropoff.
 

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^That's what happens. It's not like the wheel spin you think you see where the curve shoots up/spikes. I would pick up, 10whp, 10whp, 5whp, 5whp every time we strapped it down tighter. It looked exactly like his when we overlaid it with another h2. I thought I had a boost leak at first.
 
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