Honda CRF 300 L ECU swap

Crawling along a slow technical trail on this bike is hard. Or maybe a correct way to put it would be, that it is not as easy as it should be or could be. This is due to the fact that the throttle has a severe on/off tendency at low speeds / low revs.

At the root of the problem (I believe) are the Euro 5 emissions standards and as such the problem might not even be fixable legally in some countries. That said, I believe there is a solution out there.

Fist attempt (not a working solution)

My first “fix” was to adjust the throttle freeplay in order to have better control over the throttle. This worked a tiny bit, but does not address the actual problem.

The CRF 300 L ecu can be found under the left fairing

Second attempt (in motion)

Why not get a factory ECU from a market that does not need to adhere to Euro 5 standards? With this in mind I ordered a Thai ECU and plan on giving it a go and see if it fixes the issue.

I’ve seen reports of Thai ECUs resulting in error codes on the dash, but I’ve also read people using them without issues. How the Thai ECU works for your bike, might depend on what kind of ECU your bike is running from the factory and/or what market your bike is made for. Bikes seem to have small differences depending on where they are sold, EU, USA, Japan and so on.

Would be interesting to know how many different ECUs there are for this bike and what are the actual differences.

I`ll keep you posted on how this turns out.

UPDATE [Sept. 7th 2021]

I appears something happened to my my ECU order as it never came, nor was I charged. Ordered again and now I have a a shipment confirmation on my order. My last Thai order was stuck in the post office for 2 weeks, but I`m hoping that will not be the case this time.

Honda CRF 300 L euro ECU

Third attempt (not in play yet)

If the Thai ECU experiment fails, there is at least one more viable option. That is to reflash the second ECU with settings aimed to alleviate the issue. In all honesty, this should have been done as the second attempt, but I found about this possibility after I had ordered the Thai ECU.

CRF 300 ECU versions

There are no doubt several versions out there. So far I’ve seen proof of 4 different ones:

Thai, ending in T01

EU (Fin), ending in E11

USA, ending in A11

Canada, ending in C11

550Performance is the only one I have found so far that does reflashing for CRF 300. They only seem to have Facebook page.

Fourth attempt (not in play yet)

There is also this thingy called Full stand Next (
From what I understand, it’s device that piggybacks the ECU and is programmable via an app.

The website does not list one for the CRF 300 L, but the videos clearly show that there is such a thing. The manufacturer doesn’t seem to actually sell these and I could not find I retailer that I could actually buy one.

It may be illegal in your country to swap or reflash an ECU. Swapping the ECU may also void the warranty.

One Comment Add yours

  1. Wasin Intasarn says:

    Here in Thailand. It’s very easy to buy FullStandNext from Thai’s online marketplaces such as Shopee or Lazada.
    You can chat with the retailer if they can ship it to your country.

    Liked by 1 person

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