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Discussion Starter · #1 ·
Hello all,
I've been doing some research on fuel controllers for a gen 2 R125 ( years 2014-2018) and I am happy to announce that I found one that should fit perfectly, however only fits models up to 2016 as the company specifies. Theres a chance it can fit 2017-2018 models as well, but I am not completely sure about that and haven't contacted them regarding those specific years.

The fuel controller that fits a 2014-2016 yamaha yzf r125 is "rapidbike" made by "dimsport".
Rapidbike evo / rapidbike racing ( this one has ignition control)
Both of these controllers fit years 2008-2016.

Just using a rapidbike evo without a "my tuning bike" accesory will increase power in all RPM ranges of the engine, mostly noticeable at low/mid range RPM (2000-6000rpm) . A whole kit is recommended but its all up to you. The rapidbike evo fuel controller tends to auto-tune its own fuel map while you ride but it takes a while for it to do that without the "my tuning bike" module. What I heard from reviews and what people say, the auto-tune feature on the rapidbike evo aims for a fuel mixture a little bit more rich than
stoich (14.7:1) and the whole remap process takes around 300miles of driving for it to fully set up itself without the wideband O2 sensor.

--The perks of having "my tuning bike" wideband O2 sensor module connected to the Rapidbike EVO/Racing fuel controllers are:
-The wideband O2 sensor almost instantly changes the Injection map, so that every time you start the engine on any changing weather conditions it will automatically instantly adapt to those weather conditions, however the Rapidbike EVO alone will take a while to do that.
- Next, having a wideband 02 sensor allows you to change the air to fuel ratio however you like. most power boost wise, you can set it up to auto remap to a mixture of 13.5:1
However if you want more fuel economy, then you can set up the controller to remap itself on 14.5:1 AFR.
Sounds good, doesn't it?

Another fuel controller that fits gen 2 yzf r125's is "tuneboss" but unfortunately they dont make them anymore and they are extremely difficult to find. Tuneboss does have auto-tune feature as well, but a wideband O2 (lambda) sensor cannot be connected, this specific fuel controller is mainly good for using on big bore kits and it only runs on a stoich AFR 14.7:1 air to fuel ratio.

Gen 1 models 2008-2013

For 2008-2013 ( 1st gen models ) The best fuel controller option is "Dynojet power commander" . This controller has a auto-tune accessory as well, however the auto-tune on the dynojet uses an old version of the Bosch LSU 4.6 or something wideband O2 sensor. The rapidbike uses the newer and most likely more accurate one "Bosch LSU 4.9" lambda sensor.

NOTE: Both the dynojet and rapidbike controllers fit the 2008-2013 model, but the dynojet controller DOES NOT fit the 2014-2018 models


Please see a detailed email response from "Dimsport" regarding the rapidbike controller for gen 2 (2014-2016) R125's.

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2008 YZF-R125 (180cc)
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this is a great find, good work Hildero on doing the digging to figure this out and posting the info :)

I think my only comments/queries would be that with the rapidbike evo, if you had it on a gen1 bike and don't have the mytuning module I doubt it would "auto tune" itself in any way, no matter how many miles you do, since there's no narrowband o2 sensor (reference point for mixture) like there is on the gen2.

Also in practice for our application idk if there's really much difference between the LSU4.6 vs LSU4.9 sensor versions. I have used both types on the bike and they both seem to work fine.. so whilst there's ofc some improvements/differences I wouldn't really consider that as a major factor in the decision making of which kit to buy.

What is quite a major factor though is that from the sound of it it looks like the rapidbike kit+mytune is actually quite a bit cheaper than the PCV+ autotune module though.. is that correct?

PCV (£360) + Autotune (£260) = £620 but the Rapidbike + Mytune seemed to come out quite a bit less. Does the rapidbike mytune come with the wideband sensor included or do you have to buy that on top? Dynojet's Autotune comes with the wideband included.

That's a nice detailed response from theit tech support too - having clued-up support is a very good thing. Dynojet technical support have been excellent whenever I've dealt with them (and for me anyway) having good tech support IS a major factor in the buying decision, so it's nice to see rapidbike are also on the ball.

I'm very keen to see how well this does in practice - please do keep us posted :)
 

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Discussion Starter · #3 ·
I paid around £515 total for rapidbike evo and "my tuning bike module. So yeah, its cheaper than a dynojet kit.
 
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