Tuner
Seasoned HDF Member
Joined: Sep 2008
Posts: 14,143
Likes: 11,219
From: San Diego, CA
Do you NEED a tune...... no
Would you benefit from a tune.... yes
The M8 bikes aren't as lean in OEM form as the Twin Cam bikes were... so a Stage I retune isn't critical, but would help...
FWIW....
In '20 or '21 they changed the ECM... not sure if they changed the tune parameters at that time....
Prior tunes are only closed loop (with O2 sensor feedback) in part of the tune, mostly the cruising areas of the tune map. The rest of the tune is open loop, with no real time O2 sensor feedback. The open loop portion is in the high rpm, high load areas of the tune where AFR is most critical...
So if you are an aggressive driver and spend a lot of time in the high load and/or high rpm portions of your tune, you will be a little lean in those areas...
Would you benefit from a tune.... yes
The M8 bikes aren't as lean in OEM form as the Twin Cam bikes were... so a Stage I retune isn't critical, but would help...
FWIW....
In '20 or '21 they changed the ECM... not sure if they changed the tune parameters at that time....
Prior tunes are only closed loop (with O2 sensor feedback) in part of the tune, mostly the cruising areas of the tune map. The rest of the tune is open loop, with no real time O2 sensor feedback. The open loop portion is in the high rpm, high load areas of the tune where AFR is most critical...
So if you are an aggressive driver and spend a lot of time in the high load and/or high rpm portions of your tune, you will be a little lean in those areas...
Last edited by hattitude; Dec 4, 2022 at 01:15 PM.
Grand HDF Member
Joined: Jun 2017
Posts: 4,667
Likes: 3,966
From: Near Yosemite
Basically, the MoCo puts the tune on their bikes that the EPA wants them to put on them, not what's best for the bike as far as being too lean and the bike not running at it's best performance level. If you want what's best for your bike, tune it.
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Stellar HDF Member
Joined: Mar 2016
Posts: 2,285
Likes: 965
From: Eastern NC
Air flow is a critical part of a properly running motor and keeping crap out of the intake is vital to its longevity. I could never see why anyone would but cheap parts on a new bike that is worth $$$$$.
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Cruiser
Joined: Sep 2018
Posts: 202
Likes: 135
From: SoCal
Originally Posted by Redrodyankneck;[url=tel:20959662
20959662[/url]]You replaced both air intake and exhaust so Yes you do need a tune. SE street tuner if you value 2 year warranty.
Air flow is a critical part of a properly running motor and keeping crap out of the intake is vital to its longevity. I could never see why anyone would but cheap parts on a new bike that is worth $$$$$.
Air flow is a critical part of a properly running motor and keeping crap out of the intake is vital to its longevity. I could never see why anyone would but cheap parts on a new bike that is worth $$$$$.
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