MOTO MYTH BUSTERS ON THE TPS HACK AND EVERY THING THROTTLE BODY

if you follow any of the internet mechanics or read any of the moto groups or forums you've seen or heard guys offer up the TPS hack as a tuning method for your bike after you mod the intake or exhaust.

remember just a few years back when you bought a carbureted bike and you threw on a pipe or muffler you re-jetted for that. we're talking about the exact same need on an FI bike. change the airflow and you need to change the fuel.

i don't know who started it or who thought it was a good idea, but tweaking the TPS to fill the ecu into adding more cant and won't provie enough gas for a muffler mod on an FI bike.

imagine taking your mustang, dodge charger, or 911 to the race shop and having a full exhaust and intake put on, and the tuner says, ‘yo, bro, all we need to do for fueling is 'tweak your TPS' and you're good to go.’

that's not how it's done. no race shop, speed shop, tuner, engine builder, performance center tunes cars like that. not customers cars, not their personal cars. go to your local track where sports car guys race and field performance cars and ask for a raise of hands on how many cars there have been 'tuned' with a TPS adjustment.

but yet we all know someone or possibly have a bike ourselves with the TPS hack and think we're somehow smarter then the so called experts and their fancy add on fuel tuners, re-flash maps, or replacement ECU's.

"stuff those guys, i cranked up my TPS and my bike rips", they say.
cool story bro.

in this video we break down what's on your thorttle body, what all the parts are, what the red knob it, what the yellow knob is, and how to reset the TPS value back to spec.

Not mentioned in this video, the stock TPS setting on a 12-16 black knob throttle body is .6v

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mentioned in this video:
TPS tuning harness

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[Papparratzi]

First time I’ve understood what’s going on with those knobs and how TPS works with the ECU.
Thanks

[matthewinman]

Thanks Taco Mike! Just bought a 2022 KTM 350 EXC with only 200 miles on it. Bike was running super lean with flat spots on acceleration and constant popping on deceleration. In addition to an FMF muffler, smog delete, vented airbox cover, reed removal, O2 sensor delete, and more, the original owner altered the TPS baseline, setting it at .48 and .62 at idle. Using your video, and a TPS dongle that allowed me to reset the baseline to .40 and .52 at idle. I used JD Jetting Power Surge 6x adjustments and a new spark plug to give it some more fuel and the bike is a ROCKET. Wanted also to thank you for stocking all the parts needed to get the bike running perfect. Cheers!

[slaverace]

Mike, Great job. Good to see someone besides me helping the moto community with accurate tuning information. I get very annoyed with the snake oil salesman and the fluffy dude posting unethical scammy bullshit.

[JonIler]

Mike, you are the best. Thanks for being such a practical authority on these bikes for youtube. Your services are greatly appreciated.

[birdmanh]

THANK YOU SO MUCH. I bought a practically brand new '23 350 excf this year that had a previous owner who only put 8 miles on the bike but for whatever reason decided to messed around with a bunch of settings. The intake reeds were partially dislodged and I've had a host of stalling/low end issues. Thanks to your videos I now have a legit roadmap to reset my bike back to a totally stock tps setting so I can reinstall the reeds and install the EJK and Pro Moto endcap you suggested for budget-aware single track riders.

[redrider]

Let me start by saying I appreciate all the videos. Very good and a great help

With that said I have to comment on the TPS function and the result of adjustment that is higher than recommended.

The fuel system on these bike are extremely simple compared to cars that use multiple sensors to control fuel under several conditions.

Bikes typically have a few sensors. Air Temp usually in the air box, coolant temp and Map sensor.

Off the top of my head I don’t recall the earlier EFI bikes having MAP sensors and only recently have I seen stock systems using an 02 sensors. (Bikes using 02 sensors have a more sophisticated computer and mapping system in that they make adjustments in smaller RPM increments or windows)

That all said I wanted to speak to the comment that bumping the TPS voltage up results in a leaner condition. Mechanically that make no sense. With the throttle plate set to allow air in to achieve the specified idle and the TPS set to spec let’s say the Air Fuel ratio is 0 (not lean and not rich). As soon as you adjust the TPS voltage up and add fuel at idle you are also adding fuel as the throttle is opened because the TPS voltage window has been increased from the start. Fuel will be richer through the entire throttle sweep. With the exception of an 02 sensor which reads the actual mixture after burn and reports to the ECU so it can correct, these bike don’t have any sensors to tell the ECU otherwise other than coolant/ engine temp which is only really only prevalent when the motor is cold or hot outside the acceptable operating range. But under normal running temps the TPS is adding slightly more fuel thru the entire throttle sweep if it’s set to a higher voltage.

So how can it be leaner?

[joeanania]

Hi guys, nice video...
For riders on a budget or they just don't buy into every item out there... You do not need these harnesses to check TPS voltage..
Although the harness is put in series the connections to read voltage are not. You are not interrupting the signal you are just reading the voltage ...all you need is a paperclip or long pin, etc pushed into the two lower connectors on TPS connector...2022 500 is black and yellow/orange..i used plastic covered and colored paper clips lubricated with a little dielectric grease which you can strip on the ends so they will not short if they touch...

Hope this helps a few riders out...Joe

Happy New Year

[charlesdolen]

Just bought a tps adjustment tool and i am very happy i watched this video this morning as i was just about to go mess around with it.

[nazminazminazminazmi]

I RESPECT YOUR EFFORD AND OPPINION !!!
MY OPPINION IS THIS.
The choke opens the throttle plate physically, the TPS does not open it, the TPS is sensor witch gives the information to the computer how open it is, the TPS just transfer information from the throttle plate to the computer.
So by adjusting the TPS you trick the computer to think that the throttle plate is open more than it actually is and that makes the computer to let more fuel, but actually we did not touch the throttle plate position physically we just make the computer to think we did. The amount of air is the same because we did not open the throttle plate physically but the fuel is more because the computer think we did.
EXAMPLE:
Lets imagine that we have 1 amount of air and 1 amount of fuel as air fuel mixture. Than we make the computer to think that we have 1.5 amount of air by adjusting the TPS sensor ( 0.5 amount increase) but actually the throttle plate is on the same position and is still letting just 1 amount of air, witch makes the computer to let 1.5 amount of fuel while it actually has 1 amount of air.
SITUATION 2: higher rpm
We are half throttle open with value lets say 5 but we already made the computer to think that we have 0.5 amount increase in air witch is 5.5, so the computer let 5.5 amount of fuel to the mixture while actually has 5 amount of air.

SO HOW ADJUSTING THE TPS MAKES THE MIXTURE LEAN IN HIGHER RPM ?
HOW ADJUSTING THE TPS OPENS THE THROTTLE PLATE PHYSICALLY LIKE THE CHOKE DOES ?
AND WHAT IS YOUR OPPINION ON MY LOGIC FOR TPS ADJUSTMENT?

!!! MY OPPINION IS ABOUT A STOCK BIKE !!!

SORRY FOR MY ENGLISH IT IS MY 3TH LANGUAGE.
I AM EXITED TO READ YOUR ANSWER BECAUSE THERE IS ALWAYS SOMETHING THAT WE MAY DO NOT KNOW.

[burl_]

Best example in the internet.
I'm doing my F150 Yamaha outboard with 2 throttle body's and this is SPOT ON great video... you know exactly what you're doing thanks for your support & knowledge.👍🇺🇲💯

[pj]

So I’ve just got a 2023 sx 125 with 10 hours on it, beautiful bike, but didn’t realize how advanced and different they are compared to older carb models and I’ll be honest was in two minds on keeping it as I thought you had to have special tps tools to set values. Watching this video has made me realize that I can do it using a volt meter and plug harness and now understand what things are. Fantastic video and I will now keep the bike and learn new techniques for running and tuning the bike. I plan on putting a HGS system on, so hopefully will be ok? Thanks for a great video and putting things into an easy to understand way.

[eggnogfrog]

I have a 2019 500 exc-f, and I followed your recommendations and got the Fastway exhaust tip and the Dobeck EJK. It's been working really good so far. The EJK was the easiest thing to install. True plug and play. Thanks!!

[justindwyer]

Damn! What an excellent video! The 8 dislikes are from guys who ride old beat up carbed bikes

[NaturalCauses]

Love your videos, I learn more from you than I ever would from guys at the track or trial and error in the garage.

[jcbenson]

Thank YOU! I’m a new sxf owner (2022) and was struggling to understand how the knobs correlated and worked. I was also going to set the tps to the .60-.64 people have been going on and on about. It didn’t really make sense to me because of it being a relative number based on the idle and choke variable. This makes perfect sense now. I built s little harness tonight snd look forward to having an easier starting bike in the morning.

[TokyoOffroad]

Great video and explanation. Clear information and demonstration.

[samp]

On ya' Mike - trying to undo some 'tuning' now I've just got a Vortex and this is more or less everything I need. You're a legend. 👍

[philipsmith]

I know who you referring to... i went down that track with my 127 350, it was a waste of time, made my bike worse on power, the TPS adjust is a load of crap!! thanks for the video, keep em coming :-)

[JohnHowerton]

Thanks Mike. I suspect my 450 was molested and doesn’t run correctly. I suspected the TPS, but I couldn’t find my TPS tool. I got it running decent, but this video confirms I need to dig it up and do a total reset.

[Jmraing]

This is a good video, however! I understand these systems! I realized you were referring to a 2020 with an O2 sensor! That is a closed loop system! Some of the comments below people are talking about older models without a O2 sensor, open loop system! Those bikes can be ever so slightly tuned successfully
Via TPS! A closed loop system like that 2020 the O2 sensor will always adjust and get the reading that the ECU mapping was programmed to achieve! I have a 2015 500 EXC and that throttle body is so different the new one is a better design I have issues with the older one that will not happen on the new throttle body. I love these tech videos I always pick up something new!