Tag Archives: YZF-R125

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

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

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

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

TEST RUN on YZF-R125

This is a bit of a different sort of video for me, so see what you think…

I was testing a bunch of stuff on the bike (manual timing chain tensioner, rebuilt cooling system, stunt cage aero) and also new camera equipment and angles. I ended up shooting this as a test if a camera angle and I kinda liked the footage I got. plus it was a fun ride so thought I’d post it 🙂

Those gloves tho LINK

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

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

YAMAHA YZF-R125 ADJUSTABLE CNC brake levers


Whilst my thus-far pitiful efforts to pop dank wheelies are still going unrewarded, trying to do so highlighted some issues with my hand controls.

Continue reading YAMAHA YZF-R125 ADJUSTABLE CNC brake levers

Debunking airbox mods On Yamaha YZF-R125? – part 1

Ok so this seems to be an ongoing urban myth, whether it’s chavs drilling the airbox of their mum’s Fiesta 1.1 popular or little 125s, or even big bikes, people seem set on the idea that airbox designers are actually our mums who are trying to sneakily slow our bikes down. or something.

Why am I even going down this road?

On my bike I’ve shown the exhaust side of the engine quite a lot of love and attention, but despite the nice, big-bore shiny pipesness, she continues to run better with a little baffle in the end, like so:

The best reason I can come up with that the bike runs better with a smaller diameter exit/baffle in the end (effectively restricting the flow again) is that perhaps the exhaust is a bit much pipe for the bike – and by that I mean for the amount of air the engine is moving, the pipe diameter gets too wide at the end, which ends up with the gasses slowing down too much and actually impeding scavenging of the exhaust system. Or maybe there’s some sort of sound-waves stuff going on like with two-strokes.

Either way with the baffle in you get a little bit of torque around that 70mph point where you shift into top gear. With the open pipe it didn’t have the oomph to push through that but with the baffle it does (albeit slowly).

A couple of months ago, under what turned out to be ideal conditions on a private runway, thanks to that baffle we hit 85mph.
That was on a 15t front gear too so would have needed even more torque to make it through to the power band.

And it was absolutely equal parts terrifying and exhilarating..,as you would expect flying along on a glorified moped! 😀

Continue reading Debunking airbox mods On Yamaha YZF-R125? – part 1