Making a new fuel map for bigger injector with PCV & Autotune, on yamaha YZFR125

This video follows on from my last one and goes through the process of building a new fuel map from scratch for my 180cc YZF-R125, the way I do it, using the Dynojet Power Commander V (PCV) and Autotune (with a wideband 02 sensor).

We go through all the various components/electronic gizmos and how they interact to get to the end result of a tuned bike.

I hope this makes sense cos I had to make a bunch of diagrams and stuff for it which took forever lol xD

This video is focussed on tuning using a PCV and Autotune which is a setup that seems to be working well for me, and for this sort of moderate tuning.

I know many of you have PCFC/PC3USB etc which is a little different and can’t use autotune, and the next video will be about what your options are in that case. Thanks for your patience and I hope it’s helpful ๐Ÿ™‚


Please check out this interview I did with DynoJet UK – we covered some really interesting ground – especially if you’re thinking of buying a Power Commander (who make the Power Commanders).

8 thoughts on “Making a new fuel map for bigger injector with PCV & Autotune, on yamaha YZFR125”

  1. Would you be able to find out. How to repin the plug on a gen 1 yzfr125 to make a gen 2 throttle position sensor (tps) to work. To aloud the use of a bigger throttle body

          1. Hello
            No I’ve decided against massing around with the TPS and now I’m going to install a carburetor instead. I will let you know how I get on with it

          2. oh fair enough. A carb though? that’s an interesting decision. What’s the logic behind that? Seems like a step backwards if you’re looking for power or am I missing something?

  2. Hi just been watching some of your videos on YouTube just wondered about the auto tune Iโ€™ve just had my Wr125x 2015 (same engine) fitted with a malossi 180 cylinder kit, a malossi power cam, and italkit crankshaft and a naraku 21mm/23mm head I already had the powercommander fitted and have had the auto tune a while but never installed, tried to start the bike on the map I had no luck keeping it idling and would pop a bunch just a lot of bogging (got a high flow air filter and full arrow exhaust system too) just wondered how youโ€™ve got on with the auto tune and if you think itโ€™s worth it and will it start right up with the auto tune and start tuning it right away until it can idle Iโ€™d also love to know where you got your bigger injector as Iโ€™m looking to get one myself thanks in advance.

    1. hi Zac, wow cool setup you’ve got – that should really be going some once it’s working!

      Re the autotune.. honestly I think it’s the best money I’ve spent on upgrades so far. Having to weld the 02 sensor bung in place makes it a difficult option as it needs TIG but especially if you already have the autotune get that thing in play ASAP! I did my 180 upgrade without the autotune and then I was using a standalone wideband to try and manually tune the PCV, which was sorta working but wasn’t exactly impressive.. the bike ran ok…but then getting the autotune just made it come *alive*. Does the arrow system have an O2 sensor bung for the autotune or will you need to weld one in?

      When i did my 180 kit i literally only changed the cylinder, deliberately so that I wasn’t changing too many factors at once…so in my case ~40% bigger cylinder just meant I could add around ~40% more fuel and i was *vaguely* in the right ballpark to be starting off with, but you’ve changed several things – cylinder, cam, head/breathing etc so I think the chances of making such a fuelling “guess” with any sort of ‘accuracy’ kinda goes out the window (though obviously doing all the changes in one go makes sense from a building point of view).

      But to me that suggests that the autotune would be even more relevant for you since you should be able to basically just stick a blank map in (or your current “best guess” map), and set your AFR targets (e.g. i have 13.2 across most of the range for responsiveness, but 12.6 in the last few cells bottom right for power) and then go ride and let the autotune Figure It Out…rinse and repeat a few times…. as in the video above.

      It’s not a one-shot deal with the AT, you ride, merge the changes, ride, merge the changes and at some point you’ll have spent enough time in each position/cell of the map to have a pretty decent map built, and you should notice the map hits a sweet spot. on the original injector I already had a decent-ish map so it took around 7 iterations. In the video above I’d just done the bigger injector upgrade so was starting more from scratch and that seemed ot hit the sweet spot around 15 iterations but now she goes like stink ๐Ÿ˜€

      You can “overtune” it a bit imho, so after a while letting the autotune “learn” doesn’t really bring any benefit and can even sorta “muddy” the map, especially if you leather the crap out of it non-stop (not that I do that ofc haha :o) ) then it can sorta encourage the bike to add more fuel than is actually needed for more moderate riding, so you can end up losing some responsiveness. So when I’ve reached that “sweet spot” map (usually indicated by when i hit a new top speed or just when it feels responsive and alive) I then leave that as the base map and don’t merge the trims anymore, which is where I’m at now with the map I started in that video. I still have the learning mode option via the switch on the bars but now I just use that for adverse conditions (super cold/wet/bizzare weather) or if there’s a specific part of the map I’m looking to tune, but it 99% of cases now my “base” map is now the best/fastest option for my bike.

      With that setup you’ll probably need a bigger injector too if you haven’t already. Mine ran well in the low/mid on the stock 100cc/min injector but seemed to run out of fuel in higher rpms (probably the injector was constantly open but still not flowing enough). Since swapping to the 160cc/min in the video above she’s been much better…and your setup is likely to need quite a bit more fuel than mine so it’s prob even more relevant for you.

      Also bear in mind there’s the option of “per-gear” mapping on the PCV.. atm you have the same map for every gear, and imho the fuelling/responsiveness requirements for 1st gear are likely to be quite different from 6th…I haven’t figured out how to do that bit yet as it needs a speed sensor input and I’ve just not had time to do the research yet (i need to talk to dynojet support to find out where I get the speed sensor reading from) but I think that should also make a good amount of difference.

      Also don’t forget you can probably drop an email and see if they have a reasonable starting map for you. I know it’s a pretty bespoke setup but even something vaguely int he right direction might speed up the tuning process.

      ICYMI I did a post specifically on the Autotune:

      hmu on email at if you wanna discuss further/privately. Hope that helps ๐Ÿ™‚


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