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Discussion Starter · #1 · (Edited)
Hi guys. I’ve recently just installed a yoshimura rs5 as well as a dominator cat-back delete pipe and disconnected the servo. New ngk plugs k&n air & oil filter. bike has 35000kms (21000 miles) and valve clearance was good!
Dynod yesterday @ 103.54bhp at 14012rpm
Torque 42.06 ft/lb @ 11125.1rpm
Is that kind of low considering I’ve installed the exhaust and did other stuff. It’s a 2007 model pc40. I really just expected more. what can i possibly do to increase perhaps a few more hps or torque,
Would it make a difference if I put the original cat back in?
Ecu flash tune is really expensive around where I live ($472)
I would like to hear your thoughts on this.
Thanks in advance.
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Hi and welcome!!! 👋

That's actually decent power. Accounting for drivetrain losses and stuff, you're right in ballpark.

Did you do full exhaust or just cat-bypass and muffler? Cat's not restrictive, so removing it won't change anything. Same with replacing muffler. Only gains in exhaust comes from full system starting with headers.

Removing servo doesn't change anything either because it's fully open in top-end anyway. What it does is restrict in mid-range to increase exhaust velocity and improve mid-range torque. On street-bikes, loss of mid-range torque from removing servo just makes bike slower. Only racers benefit from removing servo to save couple lbs. And they're always running in 13-16K-rpms anyway, so who cares about mid-range torque, ex except for start and 1st run into turn-1.

You can see on dyno that mid-range flow is less than stock without servo. Fuel-mixtures are way, way too rich because ECU is expecting the higher flow of stock exhaust with servo. High-end is so-so, still too rich.

What you need is not just any flash, those are generic settings for some other bike. For best results, you need dyno-tuning with map-adjustments for your bike. Need to remove LOTS of fuel in mid-range with servo gone and less flow. Also remove fuel in high-end as well. Max-power is made right at 13.5:1 AFR, right in middle of upper/lower AFR ranges on dyno-sheet. And that can only be done on dyno with adjustments specific for your bike. Get Woolich tuning kit, lets you make unlimited adjustments.

And there's also lots of benefits from bumping up ignition-advance couple degrees for use with +100 RON petrol.

You can also tune it yourself with wideband-O2. I prefer all-digital units with datalogging. Much easier and safer than trying to do WOT runs in 4th-gear down city streets while staring at tiny little gauges. Just capture data, dump to computer later, analyse AFR curve and make adjustments in comfort on couch later. I prefer these all-digital TechEdge units from OZ. WBo2.com WIDEBAND AFR/LAMBDA (Tech Edge)
 

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Here's an example of optimum dyno-tuning on Ninja 250. Before (blue) is typical too-rich factory mixture for safety. In case you encountre bad low-octane petrol on super hot day. They tune for worse possible scenario to make sure engine doesn't self-destruct.



AFTER (red) couple hours on dyno and close to 100 adjustments, AFR has been leaned out to optimum 13.5:1 across board! This bike picked up +14% more power just from tuning alone with NO hardware upgrades!!! :)
 

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as dannoxyz posts above, a dynorun and tune of A/F could probably help....

a full (matched) exhaust may be helpfull, I was happy with Arrow Indy SS.

(2009 PC40, Arrow full system, PC5 and a dyno tune, runs nicely and makes....104hp/43 ft-lbs on dyno)

Wet weight is about 375 lbs (1/2 tank), and good at 11krpm in 3/4 gear..
 

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Discussion Starter · #6 ·
Hi and welcome!!! 👋 That's actually decent power. Accounting for drivetrain losses and stuff, you're right in ballpark.

Did you do full exhaust or just cat-bypass and muffler? Cat's not restrictive, so removing it won't change anything. Same with replacing muffler. Only gains in exhaust comes from full system starting with headers.

Removing servo doesn't change anything either because it's fully open in top-end anyway. What it does is restrict in mid-range to increase exhaust velocity and improve mid-range torque. On street-bikes, loss of mid-range torque from removing servo just makes bike slower. Only racers benefit from removing servo to save couple lbs. And they're always running in 13-16K-rpms anyway, so who cares about mid-range torque, exempt for start and 1st run into turn-1.

You can see on dyno that mid-range flow is less than stock without servo. Fuel-mixtures are way, way too rich because ECU is expecting the higher flow of stock exhaust. High-end is so-so, still too rich.

What you need is not just any flash, those are generic settings for some other bike. For best results, you need dyno-tuning with map-adjustments for your bike. Need to remove LOTS of fuel in mid-range with servo gone and less flow. Also remove fuel in high-end as well. Max-power is made right at 13.5:1 AFR, right in middle of upper/lower AFR ranges on dyno-sheet. And that can only be done on dyno with adjustments specific for your bike. Get Woolich tuning kit, lets you make unlimited adjustments.

And there's also lots of benefits from bumping up ignition-advance couple degrees for use with +98 RON petrol.

You can also tune it yourself with wideband-O2. I prefer all-digital units with datalogging. Much easier and safer than trying to do WOT runs in 4th-gear down city streets while staring at tiny little gauges. Just capture data, dump to computer later, analyse AFR curve and make adjustments in comfort on couch later. I prefer these all-digital TechEdge units from OZ. WBo2.com WIDEBAND AFR/LAMBDA (Tech Edge)
thanks for for all this info. to answer your question about the headers. It’s stock.
Do you suggest I connect the servo back again to get that mid-range flow? I think I might put the original cat back on as I think it had a better tone to it before. And let’s say I do end up getting a tune in the future, would it be best to disconnect the servo again?
 

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thanks for for all this info. to answer your question about the headers. It’s stock.
Do you suggest I connect the servo back again to get that mid-range flow? I think I might put the original cat back on as I think it had a better tone to it before. And let’s say I do end up getting a tune in the future, would it be best to disconnect the servo again?
Yeah, might as well put stock exhaust parts back in. Until you're able to get full system.

There's absolutely zero benefit to removing servo, so put it back in for immediately better mid-range. Dyno-tune it with servo in place since bike is slower before and after dyno-tuning without it.

On street bike with pump petrol, there's little benefit from full-exhaust. Most of its small gains ~3-5bhp are all in upper-RPMs 13-16K, with loss of mid-range torque. Not worth it. Primarily benefits racers for weight-savings and they actually use engine where most of gains occur. Combined with ignition-tuning for race-petrol and they can get another 8-12bhp.

On street bike, best to start with ECU-tuning package, much, much more versatile than 1-time generic flashes or piggybacks. You can optimise things like coasting-RPM where injectors are turned back on, temperature when fan is activated, no idle mode to prevent the jerk when getting off and on throttle. Works best when dyno-tuned for max-power AFR for double gains of generic 1-time flashes. And you can make unlimited adjustments in future for each additional upgrade.

Modern hot-rodding isn't done with swapping parts like in old days, now it's all done in software!!!
 

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As others have said, that air fuel is all over the place! I just had my bike dyne tuned and it made 106 Hp to the rear wheel. My bike is a 2012.
 
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