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Offline tmneill88

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Re: Low RPM Crappiness After Exhaust Change
« Reply #20 on: April 14, 2017, 07:18:04 PM »
*Originally Posted by Ralmeida [+]
Once you remove the cat and the valve, you are removing back pressure and increasing your flow, the bike computer can (if the lambda sensors are left in the header and plugged in) make up for it, but will run a lean AFR, as it thinks the bike has the cat in place along with the valve. You can not remove the cat and the valve and expect the bike to run properly, you need it tuned. the easiest way is to get the RAPID BIKE evo, it will adjust AFR to 13.2 across the rpm range on its own, as it uses the lambda sensors on the headers, Bazzaz also makes a great tune, but you need to do it on a dino, same with PCV. Welcome to the emissions regulated bikes.
Please note if you live in an area that requires emissions testing for the bike, you are pretty much stuck with the stock system, you can change the end can, thats about it.

THIS.

The bike needs a tune after that kind of modification. My AFR was way lean after the swap. Threw it on the dyno and sorted everything out.

You NEED to get a dyno tune if you change out the headers or you are going to have valve issues not too far down the road

Online SimonUK

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Re: Low RPM Crappiness After Exhaust Change
« Reply #21 on: April 14, 2017, 07:49:30 PM »
*Originally Posted by tmneill88 [+]
THIS.

The bike needs a tune after that kind of modification. My AFR was way lean after the swap. Threw it on the dyno and sorted everything out.

You NEED to get a dyno tune if you change out the headers or you are going to have valve issues not too far down the road


What was your AFR before you threw on the full system?? These bikes run extremely stock, I would expect your AFR to remain the same once the bike ECU had 'adapted' to the new lambda values.

Offline tmneill88

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Re: Low RPM Crappiness After Exhaust Change
« Reply #22 on: April 14, 2017, 08:08:18 PM »
*Originally Posted by SimonUK [+]

What was your AFR before you threw on the full system?? These bikes run extremely stock, I would expect your AFR to remain the same once the bike ECU had 'adapted' to the new lambda values.

The ECU does adapt but it has a limit. You'll see the dips in the blue line in a few areas.




Online SimonUK

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Re: Low RPM Crappiness After Exhaust Change
« Reply #23 on: April 14, 2017, 08:11:13 PM »
I meant to write 'These bikes run extremely lean stock'

Offline Ralmeida

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Re: Low RPM Crappiness After Exhaust Change
« Reply #24 on: April 15, 2017, 12:24:56 AM »
stock was almost 15.1, the reason i installed the rapid bike evolution.
2016 BMW S1000R
2016 Huskvarna FC450
2015 Yamaha TTR 230
2014 Yamaha V-Max

Online SimonUK

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Re: Low RPM Crappiness After Exhaust Change
« Reply #25 on: April 15, 2017, 12:53:27 AM »
*Originally Posted by Ralmeida [+]
stock was almost 15.1, the reason i installed the rapid bike evolution.

I guess the point I was trying to make was that they run lean in the stock setup, the addition of a full exhaust does not cause it, it is there from the factory(running lean!).

Offline Ralmeida

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Re: Low RPM Crappiness After Exhaust Change
« Reply #26 on: April 15, 2017, 01:12:28 AM »
Yes, because of emissions, they have to lean in order to get the Cat up to temperature.
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2015 Yamaha TTR 230
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Offline lospsi

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Re: Low RPM Crappiness After Exhaust Change
« Reply #27 on: October 16, 2017, 12:07:39 PM »
So, a small recap :034:

I removed the cat but retained the servo unit as I fitted custom headers. The bike run disappointingly in low revs the first time but now (after one more ride) it seems that it runs smoother (still not the same though as with stock headers). I guess that this is because of the self adjustment of the ECU. But, is the adjustment enough? I mean, if the bike runs lean from stock and we fit a hi flow exhaust system, isn't that dangerous for the engine health? Fiting the baffle is a nice idea but does it cure the lean mix problem?
I did the hole mod only because I couldn't stand that enormous cat :155: I knew there might be a small loss in low revs but I don't want my engine to have problems...

High revs aren't a problem, it rips :007:
« Last Edit: October 16, 2017, 12:09:28 PM by lospsi »
S1000R red
decatted headers, PCV, Ohlins steering damper, rdmoto axle sliders, custom seat, hp levers, MRA screen, smoked intergrated tail light, radiator guards. I want more but no money left...

Offline Nihil

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Re: Low RPM Crappiness After Exhaust Change
« Reply #28 on: October 16, 2017, 12:39:33 PM »
I've had a straight pipe, no cat headers, no valve, Arrow can for more than 40,000km.
No problem at all other than 3 minutes crappiness when engine and exhaust are cold from start.

 


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