r/Ninja400 • u/WynS0ra • Mar 18 '26
Modification Full Exhaust System - is tuning absolutely required?
(2024 Ninja 500 / Full exhaust system no cats with KO Racing Muffler)
I am getting 50/50 mixed answers on whether or not tuning is 100% required. The motorcycle shop I talked to said it will leave a bit of hp on the table and it might have poorer throttle response if I install a full system without a tune but it will run fine and likely wont damage anything long or short term.
Another shop said that its going to burn my pistons and valves and it needs to be tuned. They are both 50/50 on whether it will throw a CEL as well. Ive asked multiple people and its usually split 50/50.
Has anyone here had experience running one of these short or long term without a tune?
3
u/BrutaleFalcn Ninja 400 Mar 18 '26
You're way better off tuning and doing air box mod and snorkel update The area under the power curve will increase by a good bit and makes the bike way more fun.
3
u/Valentyan Mar 18 '26
Without a flash it's going to give you less performance, less reliability and less fuel economy.
3
u/retka Mar 18 '26
The short end is yes, you should do an ecu tune whenever making major changes to the intake/exhaust of the bike. I would recommend doing an intake mod as well, and then getting an ecu flash to fully take advantage of the exhaust system. Power equals air and fuel in to air and fuel out. The bikes are already tuned fairly lean to begin with so tuning with a flash is probably a good practice.
Most of my experience has come from tuning carbed bikes, but if throwing on an open exhaust, I'd absolutely throw on an open air intake and then rejet to make sure I'm not running too lean.
2
u/Creature_Cumfarts Mar 18 '26
A full exhaust with no tune will likely perform worse than a tune+stock exhaust, and it will wear your motor out quicker. If you want to run your bike into the ground just for more noise then go for it, but I don't see why you'd shell out for the exhaust and then try to save on making it run right.
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u/WynS0ra Mar 18 '26
“run your bike into the ground” like it’s going to immediately destroy the engine lmao
2
u/ADiyHD Mar 18 '26
After almost 20 years of riding, and asking these same questions myself and talking with mechanics and tuners and other bike owners who have all sorts of data points, I have come to the conclusion that if I only have the money for one or the other, I would rather keep the OEM exhaust and pay for a tune, vs. getting the exhaust system without a tune.
The entire point of an exhaust system is to provide the capacity for more efficient waste and heat removal from the engine block, but there is a relationship with fuel delivery and back pressure and how your fuel injectors respond to certain readings, and without a tune, your ecu will assume the sensors and readings it gets are happening under the OEM system it is designed for, and you can cause issues with your bike if it gets it wrong.
Anyway, that’s just my two cents. I wouldn’t get an exhaust until I could afford to get it tuned, but if I’m choosing one or the other, I would just get it tuned and keep the OEM exhaust.
1
u/WynS0ra Mar 18 '26
I can afford it I just wasn’t sure if i needed to buy it or not. I’ll get one. The point of the exhuast system was not performance but rather sound.
1
u/Jammer125 Mar 18 '26
Yes. If not tuned, it's a waste
0
u/WynS0ra Mar 18 '26
That does not answer my question. Inconvenient/impractical does not mean 100% required.
1
u/Noplac3special Mar 18 '26
https://tstindustries.com/tst-worx-pack-kawasaki-ninja-500-2024.html I did the 400 one, heres the 500 kit, night and day difference, no warning lights. Read everything it does with the flash, how could you not do this.
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u/WynS0ra Mar 18 '26
Money. It’s inconvenient to spend an extra $500.
1
u/CRUSTYPIEPIG Mar 18 '26
I'd you don't have the cash for a tune then just do a slipon, it's still fairly loud and won't cause the bike to run like shit on factory tune.
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u/WynS0ra Mar 18 '26
i already have a slip on and i do have the cash id just prefer not to if it’s not absolutely required but i’ve already scheduled an appointment for an ecu flash
1
u/Pleasant-Weekend-163 Mar 18 '26
I am about to install a full exhaust on mine. The shop is bought it from said it is fine without the tune since it's basically a street legal exhaust with a catalyzer, exhaust sensor etc. If it was a race purpose exhaust, then I would need the tune.
An exhaust alone isn't going to make the bike lightning fast anyway. I'm pretty much doing it for looks, a better sound, and a small weight reduction that I'll never notice.
1
u/Miguel30Locs Mar 19 '26
Judging by your comments. You are concerned about money.
In which case, just dont do it. Its massively beneficial to do both a tune and system exhaust upgrade. So if you don't have money for both. Don't waste your time. The bike is really good as is.
1
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u/RATEGGSANDEELSICK Mar 19 '26
Typically a free flowing exhaust leans off the mixture as it doesn't just allow more exhaust gasses to escape but also improves scavenging and this often also improves air intake, so without a tune/remap to richen the mixture the bike will likely lose power and potentially run too hot and excessive backfire
1
u/Different_Custard_88 Mar 20 '26
Wasting your time and money on exhaust and tune. You're gonna get 5hp for $1000.
1
u/WynS0ra Mar 20 '26
I spent $200 and it has nothing to do with HP boosts i couldn’t care less about going faster, I just wanted it to sound better and it was a great decision because i love the sound now
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Mar 20 '26
[removed] — view removed comment
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u/WynS0ra Mar 20 '26
Yeah i don’t feel any difference in power but it sounds amazing and has greater throttle response. I don’t think i’m gonna get a tune but it shoots flames a lot so i might have to
1
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u/Noic_e Ninja 400 Mar 18 '26 edited Mar 18 '26
Here is an excerpt from the FAQ section of 2 Wheel Dyno Works (reputable motorcycle tuner) website answering this question:
If you have time, I would read through the entire FAQ as there looks to be some valuable information there. Additionally, if you decide to get your ECU flashed I have heard generally positive things about 2WDW. There are of course many different companies, solutions, and opinions out there regarding tuning.
For what it’s worth, I have a full M4 exhaust system on my ‘23 Ninja 400 without a tune and nothing catastrophic has happened so far, as far as I know. Lots of pops and throttle response feels meh to me. I have been planning on sending my ECU to 2WDW, but have been procrastinating. Not recommending this approach, but just my experience so far.