Tag Archives: YZF-R125

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 🙂

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Winter updates

been a while since last post…so this will be a bit all over the place while I catch up. Apologies, please bear with me, there’s a lot to cover and some really exciting stuff to follow. Details on that as soon as I know for sure 🙂

Sooooo… the B-motor investigation didn’t go so well, scored bearing surface on the little end (wrist pin) bearing on the con-rod, which means new con-rod, which means bottom end apart and basically new crank which comes with free con-rod (or separate/re-join crank which will cost about the same as replacement). Ran out of budget on that so that’s been paused for the moment.

very expensive scratches
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How to convert PCV maps to PC3USB easily (and free)

So I just figured some stuff about how to convert Power Commander V (PCV) maps to Power commander 3 USB (PC3USB) so I’ve done a little write up of it.

You can import older PC3USB maps into the PCV, and you can import PCV maps into the PCFC, but you can’t import PCV maps into the PC3USB, and you can’t import PCFC maps into the PCV.

Except now you can…and it’s super easy to do: Read more here

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Autotune – game changer

(for me anyway)

There’s been quite a lot gone on here lately.. I’ve not posted for a variety of reasons which I’ll also get into along the way.

I’m trying to work through the backlog now and will have to post it in parts. This is part 1 – which is a little catchup on the autotune box I added to my bike recently, which we’ll build on for the next part/s.

I also realised that my email subscription thing on here is all messed up so till I get that figured out I’ve added a thing so you can login and comment with a wordpress.com account, as well as google and faceballs and whever other type of accounts. I hope that makes it easier to comment and ask questions etc.



The story so far

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Wideband O2 sensor on YZF-R125 with 180cc kit, for street tuning

Short video running through installing and testing my wideband O2 sensor to try and get the fuelling right on my YZF-R125 with 180cc kit. I was kinda nervous about hacking a big hole in my nice shiny stainless exhaust but I guess that’s part and parcel of getting into the more interesting tuning stuff…

links:

LDPerformance wideband O2 sensor: https://ldperformance.co.uk/product/wideband-controller-for-bosch-lsu49/

carbide grindy bits:https://rover.ebay.com/rover/1/710-53481-19255-0/1?ff3=2&toolid=10044&campid=5337039155&customid=1&lgeo=1&vectorid=229508&item=254299095337

motorcyclespareparts.eu (clutch diagram & parts): https://www.motorcyclespareparts.eu/en/yamaha-parts/2008-yzf-r125-motorcycles/clutch

6-spring clutch boss conversion from MOTOGAGA (untested, mine hasn’t arrived yet): https://motogaga.com/clutches-clutch-housings/567-6-spring-sports-clutch-conversion-yamaha-r15.html

 

My links:

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Patreon (support the channel): https://www.patreon.com/northcust

Twitter (realtime updates): https://twitter.com/northcust

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Refitting the engine on the YZF-R125, now with 180cc big bore kit

 

not a lot to say here really – engine is rebuilt on the 180cc big bore kit, this is just putting it back in the bike..if it runs then we’re pretty much back in business!

My links:

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Patreon (support the channel): https://www.patreon.com/northcust

Twitter (realtime updates): https://twitter.com/northcust

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YZF-R125 engine rebuild (180cc big bore kit) – can I fix it?

This video is me trying to reassemble the broken motor for my YZF-R125, this time with a 180cc big bore kit. Link for the cylinder I bought (which looked *beautifully* machined): https://www.ebay.co.uk/itm/151763913131

Apart from that I only ended up buying the top cam chain guide and one replacement head bolt (which looked like it was going to round off) and a bunch of oil and filters. I’d bought a new cam chain too but hadn’t realised you have to split the bottom end casing to fit it..and you’re supposed to change the main shaft, cam chain and cam gear as a set, so i guess not this time.

Videos I found helpful for preparing the piston, rings and wrist pin etc:

wrist pin fitment (this was super useful):
https://www.youtube.com/watch?v=siG5W…

measuring ring gap:
https://www.youtube.com/watch?v=zHK1M…

installing rings:
https://www.youtube.com/watch?v=rgu5v…

My links:
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Patreon (support the channel):
https://www.patreon.com/northcust

Twitter (realtime updates and nonsense):
https://twitter.com/northcust

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YZF-R125 Engine tear-down & failure analysis – what went wrong?

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Engine out on the YZF-R125

The first step towards getting my beloved R125 running again is going to be taking the engine out to see what went wrong and whether I can fix it or whether I have to replace it.

If there’s any way I can fix the motor then I’m going to try and do that, and possibly slip a 180cc big bore kit in there too since I probably have to replace the cylinder anyway and my very patient insurance folks have said they will insure it if I go ahead.

Continue reading Engine out on the YZF-R125
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