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Power Commander V

3366 Views 9 Replies 6 Participants Last post by  racerrrrx
Who has a PCV and M4 Street Slayer on their bike?
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Following. I'd like to get this set-up for my bike this Spring.
Review the other threads on the "Exhaust and Fuel Delivery Board" - I seem to remember someone running that combo.
Hi guys, I would like to run the same setup M4 Slayer + PCV + Block off plate but I have a few questions. Firstly I know it's recommended to have the PCV with the exhaust but is it nessessary? And will it cause any damage to the bike? From what I understand the bike will run lean withought the proper tune and it will backfire (pop) quite a bit, which I heard can do damage to the bike (is this correct?) and that's where the blockoff plate comes in? So wondering what will happen if I install the exhaust and the plate only? The reason is i just want the exhaust for the sound and not performance but not looking to loose power or cause damage to the bike in the long run either. And second question, if it is nessessary to get the PCV, does it come pre-tuned for the R3 (can you order it pre- tuned for the R3 with the M4 exhaust is what I mean)? And lastly is any of this gonna throw any check engine lights and so on after removing the cat etc?
Hi guys, I would like to run the same setup M4 Slayer + PCV + Block off plate but I have a few questions. Firstly I know it's recommended to have the PCV with the exhaust but is it nessessary? And will it cause any damage to the bike? From what I understand the bike will run lean withought the proper tune and it will backfire (pop) quite a bit, which I heard can do damage to the bike (is this correct?) and that's where the blockoff plate comes in? So wondering what will happen if I install the exhaust and the plate only? The reason is i just want the exhaust for the sound and not performance but not looking to loose power or cause damage to the bike in the long run either. And second question, if it is nessessary to get the PCV, does it come pre-tuned for the R3 (can you order it pre- tuned for the R3 with the M4 exhaust is what I mean)? And lastly is any of this gonna throw any check engine lights and so on after removing the cat etc?
That's like 8 questions - take a look at some of the other threads on this very board - many of your questions have already been discussed in some detail, but briefly:
No
No
Maybe - mine ran rich
Backfire through exhaust - not necessarily bad, backfire through throttle body - not good.
Block off plate provides better A/F values via lamda sensor
Not much
Yes
No
Thank you for your answer, I have read through all the threads but always get confused and unconclusive answers. How does backfire through throttle body happen? And will it happen with the change of the exhaust? This is what I don't get.. You say nothing bad will happen and no damage to bike will be done and that it's fine withought a tune and then you say not 'necessarily bad' and bad if it's through throttle body... Also you say yours ran lean (what setup?) Sorry for all the questions I just don't seem to get everything. So am I fine running the m4 with stock ecu and block off plate?
1. install the shiny/noisy bits you like
2. get bike dyno tested
3. if bike runs too lean (according to the PRO running the dyno) add a PCV
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Thank you for your answer, I have read through all the threads but always get confused and unconclusive answers. How does backfire through throttle body happen? And will it happen with the change of the exhaust? This is what I don't get.. You say nothing bad will happen and no damage to bike will be done and that it's fine withought a tune and then you say not 'necessarily bad' and bad if it's through throttle body... Also you say yours ran lean (what setup?) Sorry for all the questions I just don't seem to get everything. So am I fine running the m4 with stock ecu and block off plate?
There's no guarantee a new thread won't cause you confusion either.


A backfire through exhaust is not uncommon and is usually caused by unburnt fuel passing through when you chop throttle - if it happens under acceleration, then there are (timing, valve, mixture) issues likely not related to the exhaust. A backfire through the throttle body is often caused by incorrect ignition timing and has nothing to do with the exhaust system set-up.

You should be fine. racerrrrx +1
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1. install the shiny/noisy bits you like
2. get bike dyno tested
3. if bike runs too lean (according to the PRO running the dyno) add a PCV
Depending on how much your local tuning shop charges for dyno runs, it may be better to just bite the bullet and get a PCV or Bazzaz unit. Prob only $100 or so more, and you get something that you can continually update yourself.

I'm guessing that any exhaust system that removes the catalytic converter will cause enough problems that just a block off plate alone won't solve. You'll probably need some fuel remapping.

Sure, your bike won't blow up without a new ECU. But With my full Yoshi system, it just didn't run well until I put in a Bazzaz unit.
No matter what your setup you should be dialing it in on the dyno
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