Tag Archives: YZF-R125 stunt build

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:

===============================

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

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

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:

===============================

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

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

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:
===============================

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

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

Fitting the motox bars to the YZF-R125: success!

ok well as regulars might know I’ve been on a bit of a mission lately to repair the wear-and-tear from the wheelies & drifting practice so far, as well as protect the bike for future wheelie activity.

It’s been hard on the bike, and highlighted any pre-existing weaknesses, but I also learnt a lot about what I want and need from the bike in order to do this in a not entirely half-assed way.

I love the clipon risers I’ve been rocking most of this year. My “ideal comfort position” was with them not even on full height, about half height. It added maybe 1.5″ each side in height and the same in width. It didn’t mess with the aerodynamics too much, but gives excellent control from the slightly wider stance, but you can still get down in the corners when you need to. Nice.

However, not so good for standup wheelies. Angles all wrong, doable but feels unnatural. We don’t have lots of power to play with so I need to try and optimise my position as far as I can. I needed to try and push weight back so she comes up more easily, so I added a bit more height to the clipons, which helped but was higher than I’d like and the angle was still wrong somehow, and the brake reservoir hit on the screen constantly which is super annoying.

Continue reading Fitting the motox bars to the YZF-R125: success!

Random updates – Wheelies, repairs, stunt cage, rear hand brake

So whilst I kinda prefer to write posts or make videos about a specific subject from start to finish, that’s not how my life is working at the moment, and whilst I’ve not posted that doesn’t mean I haven’t been up to much…quite the opposite, I’ve been doing loads and have loads to report on different fronts, but none of them has particularly concluded in a meaningful way yet…so perhaps this will have to be done in stages as things progress.

So for reasons best known to nobody I’m still hell bent on figuring this wheelies & drifting thing out on the 125, especially since now I *know* it can be done.

I’ve found myself a couple of quiet little spots to practice at (private property/non-road), my exhaust’s deliberately not obnoxiously loud so as not to annoy anyone and I don’t tend to stay in one spot very long either…so I’ve had a few decent little practice sessions without any complaints so far.

Continue reading Random updates – Wheelies, repairs, stunt cage, rear hand brake

MotoX bars on YZF-R125

So it turns out I’m not the only person who’s interested in having different bars on the R125 – someone who I’ve been chatting to a lot about these bikes is also interested in this but didn’t want to go any wider with the bars – my clip-on arrangement added a few cm each side to the width (and you notice the increased drag so it’s a fair point.

Motox bars would be about the same width as my clipon setup but they can also be trimmed down a bit so should be no wider than the standard bars, just a little higher and angled a bit differently.

So after much back and forth about how best to do this and whether it would be strong enough I thought enough discussion, time to drill some holes and try bolting the motox risers onto the yoke directly and find out for sure.. and here we are.

There’s nothing like drilling holes in something to get a feel for just how solid it is (or not), and in this case I got the impression this yoke is actually pretty damn sturdy.

At the point of the holes I guess it was looking like ~5mm thick, and add to that the strength from the shape of the casting and any reservations I had about the top yoke not being strong enough were pretty much put to rest.

What struck me as important was to get a nice even pull on the bolt so that everything lines up correctly and doesn’t end up with weird forces putting stresses in places there shouldn’t be stresses, which could lead to cracks, bolt snappage or things wearing loose over time, none of which we want on our main means of steering the bike.

Continue reading MotoX bars on YZF-R125

YZF-R125 CLUTCH IMPROVEMENTS AND rear HANDBRAKE PROGRESS

I don’t even know where to start so I’ll just chuck some pics in and hopefully it will make sense along the way

And the quest for wheelies continued…

Ok so i beginning there was the normal clutch lever, then we went shorty two-fingers (which was better) and then slipping off once too often when pulling up with two fingers I realised why they all have 1-finger levers…

Love these lovely CNC’d numbers but wheelies say you gotta go

The 1 finger lever (ebay link) is actually bizarrely comfortable like I’m thinking why the hell did we have all that other nonsense before. The movement is pleasantly smooth and precise. Also the lever has 3 positions where you can hook the cable in which slightly change the feel and cable orientation to suit your hand. There’s a wee bolt to set the resting position of the lever too so you can get it set up exactly how you want. So much fun with one finger…anyway.

Continue reading YZF-R125 CLUTCH IMPROVEMENTS AND rear HANDBRAKE PROGRESS