790 Adventure Decat/Tune Results

Discussion in 'Parallel World (790/890)' started by turbofan790, Nov 5, 2019.

  1. turbofan790

    turbofan790 Been here awhile

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    Last week I left my 790 with Rottweiler so they could work on their 790 Power Commander tunes. Ultimately, the results were surprising to me and I figure you all would like to hear about it.

    First, a printout showing all the results. Click to enlarge.
    All runs dyno.jpg

    Description is on the sheet, but to parse it: clear improvements from tuning. The blue line is stock. Green line is Rottweiler's bike with Arrow decat and Arrow open muffler. Red line is Rottweiler's bike with the full stock exhaust, but tuned with the power commander V. Orange is my bike with the sharon exhaust.

    Before anyone asks - my bike made the same power with the stock exhaust with only the tune as Rottweiler's bike, so they're very closely matched motorcycles. Because of this, we believe these graphs are comparable even though we never put the Sharon exhaust on the Rottweiler bike.

    Some interesting things here. First: the highest peak power was achieved with the stock exhaust and a tune - the decat, even tuned, doesn't make more peak power than stock. Not shown is an untuned decat, which also did not make more power than the blue stock line shown above.

    The Sharon exhaust doesn't make as much power as the stock exhaust, OR the Arrow decat + muffler. Definitely wasn't thrilled to find this out, but it's still a great looking exhaust that is lightweight. At least that's my consolation. Also MUCH cheaper than other Decat + open muffler options, though the fit isn't as good. I'll keep it, but if it gets damaged in a crash, I'll likely just reinstall the cat and do a slip-on... and gain some power back.

    Let's look closer at stock VS tune only.
    Stock Vs tune only.jpg

    Small gains below 4k, but very significant gains starting at 4500rpm.

    Now, stock VS Decat, open muffler, and tune:
    stock vs. decat + tune.jpg

    While the decat did not make more peak power, it does have a considerably fatter midrange. I would say that fatter midrange isn't enough to be worth decatting on its own, but it's a nice perk if you choose to decat.

    At the end of the day, if you're decatting for power, it's not worth it. Yes, slightly fatter midrange, but only slightly, and no top end gain. If you're decatting to save weight and reduce heat, without the expectation of greater output, it's probably the cheapest and easiest way to shave a few pounds off the bike.

    Some notes on the stock tune. Several of you have noted that the bike feels like it really comes along at 6k rpm. Here's why:
    View attachment 1978416

    The stock tune is extremely lean up til that point. That's 14.5:1 AFR at full load/full throttle - crazy lean. It finally gets down to reasonable AFRs at 6k RPM, which is why the bike suddenly feels so much healthier.

    Finally, riding impressions. Spent all day on the bike on Saturday. I had previously spent a day on the bike with the Sharon and no tune. Though my dyno result post-tune with the Sharon exhaust was a bit disappointing, the bike felt completely different. MUCH smoother fueling from low RPMS. The bike pulls very cleanly even at large throttle openings from 2k rpm, none of the feeling of flaming out like stock. Power delivery is smoother and crisper, and high RPM power is noticeably better. Transitions on/off throttle were also smoother. Unfortunately that only lasted a couple of hours, because we accidentally left the O2 sensors plugged in which resulted in the OEM ECU taking over again and reverting to the stock tune. :doh Just have to get in there and unplug them and I'll be back to smooth, tuned glory.

    Shout-out to Chris at Rottweiler. Awesome shop, great guys. Looking forward to buying more stuff from them.

    Attached Files:

    #1
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  2. turbofan790

    turbofan790 Been here awhile

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    In case it's unclear, claims that decatting the bike will somehow harm it are unfounded and nonsensical. Even with the decat and no tune, yes the bike was very lean but not significantly worse than stock. I am not a fan of how the bike runs with a decat and no tune, so I personally would not recommend a decat without a tune... but frankly, overall, I recommend a tune whether decatted or not due to the improvements in rideability and fueling.
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  3. kubcat

    kubcat Been here awhile Supporter

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    So the "Arrow Decat with Rotty Decat Tune" (green curve) looks like what I want - noticeable increase over "Tune Only" (red curve) in the midrange starting after 4200 rpm, where I spend a lot of time in 3rd gear, while giving little to nothing away at the top - assuming the torque curves reflect similar improvements. I'm sure the advantages will only improve as Chris tweaks the custom tune.
    #3
  4. Velociraptor

    Velociraptor TrackBum Super Supporter

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    Interested to know what happens with the gas mileage with a tune. I have no big complaints with my stock tune with Akra pipe. Loving the gas mileage. Mid 50s to low 60s per US gallon.
    #4
  5. TrailTrauma

    TrailTrauma Nemophilist

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    Awesome! Thanks for posting this up man. Makes a decision much easier. Looks like a simple OEM setup with the Rottweiler map would be a great first step. Next step? A hole saw and a modification of the stock can, or a slip on.

    An open slip on wouldn't affect the performance much, right? It's more the cat delete or not which affects performance.

    Did Chris mention the PCV with the 'auto-tune' and how that might improve your tune over time? I have a Thundermax auto-tune on the HOG and like it's performance. Every key cycle it tweaks 2 maps .. one for mellow cruising, and a second for when I'm on it.
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  6. turbofan790

    turbofan790 Been here awhile

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    Don't expect a slip on to affect performance vs. a full stock exhaust, should be same/similar results.

    Fuel mileage will be lower. How much? We will see.

    Main benefit of auto tune at this point is you can Have the tune without a check engine light. If doing a full closed loop tune the check engine light stays on due to having O2 sensors unplugged.
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  7. TrailTrauma

    TrailTrauma Nemophilist

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    I'd have to see a photo of that engine light to make a choice. Is it just the small engine icon or an error message across the bottom. As long as it's a small icon, and any other warnings still come up at the bottom of the TFT then it seems moot.
    #7
  8. turbofan790

    turbofan790 Been here awhile

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    Same small icon that pops on to the left of the screen when you first turn the key. No on screen message ever.
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  9. Nowwhat

    Nowwhat I'll Go Second... Super Supporter

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    Good Stuff.....thanks for posting....

    All of it is going to change when the intake comes out hahahaha.....need more air in if you want more air out.....can you leave your bike there....we are going to need some more pulls......hahaha
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  10. TrailTrauma

    TrailTrauma Nemophilist

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    Looks like an 'open muffler only' has a different race map at Rottweiler because in the drop down menu there is also a stock race map choice as well. Chris wouldn't differentiate if they were the same I'd think. I'll have to email him and ask. If I can drop my stock muffler off at my shop and have the head mechanic fabricate a larger hole, and inner pipe etc it would have a similar function as an open, with a fraction of the pricetag. But if that means a different map then it would be good to know. I spend the money saved on modding the OEM can on the Samsung 8" tablet I'd like for NAV duties. That will become the priority as I push further from home next season.
    #10
  11. turbofan790

    turbofan790 Been here awhile

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    The tunes may be slightly different but the performance isn't significantly.
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  12. ramirin

    ramirin Ready to push

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    I would opt for decat & open muffler because of heat (and sound). It seems to be safe choice according to Rottweiler tests. But I still wan't to see a bike with 20-30k on clock all without cat.

    But what about talks of 'ecu going to protect mode' with signifigant power lose after a while if running without O2 sensors?

    I don't have that much experience tampering with ecus - how do you setup new map? External device controlling ignition & injection?
    How can the ecu take over after a while like in your case?
    #12
  13. turbofan790

    turbofan790 Been here awhile

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    Great question, that's getting to a level of technicality beyond my understanding. This is my first time having stuff done to my bike rather than me doing it myself, it's a little disconcerting for me since I'm used to knowing how it all goes together and interacts. My guess is that the tech plugged the O2 sensors back in after my bike came off the Dyno, and it took a minute/couple power cycles for the ECU to revert back to OEM maps and O2s.

    Haven't seen anything like a protection mode. We will have to see. Only way to formally disprove that along with everything else Coober has posted will be with time.
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  14. SEK_Nick

    SEK_Nick Been here awhile

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    What kind of fuel economy do you give up to go with a tune only (Stock can + cat remains)?

    I'm not really looking for louder on the bike, but having a bit more ass on the low end would be welcome. Don't get me wrong, I feel like there's enough there; but if a little is good, more must be better!
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  15. turbofan790

    turbofan790 Been here awhile

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    Remains to be seen.

    I ended up at about 42 mpg on my Saturday ride (just went and filled up right now to check).... but that doesn't mean much. I've seen everywhere from high-30's to high 50's with the stock tune depending on the ride.
    #15
  16. Gaulin

    Gaulin Orange (& Blue) Crush

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    Thanks for posting all this Turbo, it's great info. Any chance do you have the AFR graphs ? Or are they smooth 13.2 all the way across and nothing to see ?
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  17. turbofan790

    turbofan790 Been here awhile

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    Odd, I meant to post it in the original post where I started talking about AFRs. Looks like I grabbed the wrong photo there. Edited, should be showing in original post now.

    Basically flat 13.2 all the way, whether decat or not with the appropriate tune.

    Attached Files:

    #17
  18. Gaulin

    Gaulin Orange (& Blue) Crush

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    I'm starting to really consider a PCV, and loss of fuel economy is definitely an issue. One thing they can do is map individually in each gear, it might take an add-on module, not sure about that yet.

    So change the fueling tables to lean it out in 6th gear between 4000 and 5200-ish RPM. That will cover highway cruising without sacrificing off road performance and minimize negative effects to on road. Do the same with 4th and 5th if you so desire. I need to talk with Rottweiller on this.....
    #18
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  19. Gaulin

    Gaulin Orange (& Blue) Crush

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    Are you bringing your bike back to put on the dyno after a certain amount of miles to determine if there is an ECU protection mode ?
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  20. Nowwhat

    Nowwhat I'll Go Second... Super Supporter

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    I have the maps....PCV...Autotune....and a 47T rear sprocket....I am getting high 40's mpg..like 48....while riding it like a teenager who wants to hear the exhaust all the time....

    The stock bike actually goes rich...in the upper revs...I am not sure the tune is going to hurt your MPGs much
    #20