Yamaha YZF-R125

How not to remove lower timing gear on YZF-R125

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This is the first of my “descent into madness” series of videos where I’m trying to rebuild this spare R125 engine.

I bought the engine as broken and when I took the cylinder off the bearing surface of the little end was damaged, which means the crank needs to be pressed apart to fit a new connecting rod.

So basically I have to take the entire engine completely apart just to get to this one dumb piece to replace it.

The videos are out of sequence but I have such a backlog and there was going to be a plan and it all went to crap. Every expert I was hoping to get to help me with this basically just disappeared or didn’t follow through, so I’ve finally resolved to buying the kit and figuring out how to do it myself.

Even though the engine in my bike has issues (from when I messed up a couple of years ago), despite that it’s done another 5k on the 180 cylinder (even wiht the timing chain issues) and I have not gone easy on it 😉

I’ve had a few people asking me to rebuild engines and do upgrades etc which is very cool, so it seems like it’ll be worth learning how to do it.

Hopefully this all ends with an engine dyno and building mad engines as was always the dream/plan 🙂 I’ve added this video to a new playlist for the B-motor rebuild so I can add all the other videos to it as I work through them. Thanks for watching and thanks to SXparts.com for sourcing hard-to-find components like the lower timing gear.

UPDATE: I said in the video (at 2:08) the lower timing gear wasn’t available, well it turns out i was wrong on that and you can get it here. Thanks to A for the link 🙂 https://www.cmsnl.com/products/sprock…

#YZFR125 #R125Life #bikelife #bikewife

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I’m on Instagram – NEW R125 FRAME

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Ok well you probably know how I feel about facebook products but if anything’s going to get me to cross that line it’s bikes. And it did..Actually so far I quite like it. Lots of nice picsand seems like lots of similarly bike-obsessed ppl but less noise than fb. Biker twitter has decidedly less outlaws than I was hoping for so perhaps Insta is a better place.

Either way..if you’re on there, of if we’ve seen you whilst out riding, please do follow + say hi 🙂

Let’s see if insta is a better outlet for my photos…

https://www.instagram.com/north_cust/

Also: this just happened:

For about a year I’ve been looking for a cheap frame to mount the turbo motor in, kinda because I was hoping it would be easier than making a motor stand..You sometimes see written off frames o ebay for peanuts and I was hoping to get one and perhaps cut out what I needed if it couldn’t be put onthe road anyway. You can get clean frames with paperwork from italy and germany but they’re usually £500+ and that’s a bit much to spend on somethign wich may never even make it to he road…but then at long last I found this one the other day in Germany.

Continue reading I’m on Instagram – NEW R125 FRAME →
Blog, Yamaha YZF-R125

Interview with dynojet – in detail on power commanders

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Intro/background

So as you may have seen the last few videos have been focussing on fuel mapping with the Power Commander.

Till now the videos have been focussed on the Power Commander V (PCV) since it’s the one I have, but it seems like the Power Commander FC (PCFC) and Power Commander 3 USB (PC3USB) are more widespread, perhaps due to their lower cost.

In the last video we went through the process of how I build a map for my bike using the PCV + the attached autotune box which links to a wideband O2 sensor to adjust the fuel map on the fly.

But as far as I could tell there was no way of doing that with the PCFC or PC3USB. They don’t have the onboard CAN bus (a messaging protocol which car devices use to talk to each other) so there’s no way to link them to a wideband, and if that’s not how you tune.. how *are* you meant to tune them?

Lots of people talk about “chuck a power commander on it and get a bit more power” (aka “Common Knowledge”) but I never found anyone willing to go into more detail on how to go about doing that in a slightly more scientific way, or why you should have one box over another. Or at least I couldn’t find anyone *who knew what they were talking about* who would do so.

Mechanics are often better at doing than explaining which doesn’t help feed this “pool of common knowledge”, and they arguably also have a financial incentive to not tell you how to DIY since that potentially deprives them of future business. That’s just capitalism though, and also not necessarily how my brain works, so here we are.

Continue reading Interview with dynojet – in detail on power commanders →
Yamaha YZF-R125

Removing the flywheel on YZF-R125

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This is just a quick little edit i’ve put together because I know that at least one of my viewers is about to do the same process, so wanted to show a little what to expect (and see for myself!) what wonderful mysteries line beneath the stator cover etc.

This is working on my “B-motor” which is a motor i got as a non-runner, hoping to just put a new cylinder on and get it in the bike, but then whilst removing the seized wrist/gudeon pin the bearing surface on the little-end got scored, which means now I have to pull the crank out, get the crank separated, fit a new con-rod and then re-assemble. So since i have to split the casings and whatnot I might put a forged con-rod and fresh bearings where I can, though in general this motor is a lot less shagged than my current one .

I’m not looking to do a mega-rebuild on this, just get it back to working, stick a 180cc cylinder and a stage 2 cam on (both of which I have already), and then get it into the bike so I can start work in rebuilding my ‘A-motor’, which will be getting The Works (with a view to forced induction)…so this is a bit of a trial run.

With a bit of luck this build should see us comfortably into the 90-95mph sorta territory, given we’re already knocking on 90’s door on the current (very knackered) A-motor.

I’ve not had one of these motors apart to this extent before so please don’t use this as a “how to”-video, it’s likely to be more useful as a “here’s some mistakes to avoid”-video (like losing the woodruff key, as you’ll see), and perhaps might be useful to see what special tools are needed to actually take these beasties apart.

STUFF YOU MAY NEED:

replacement woodruff key in case you lose it like I did:
https://www.ebay.co.uk/itm/GENUINE-YAMAHA-WOODRUFF-KEY-90280-03X00-YZF-R125-WR125-R-X-CW50-AEROX-JOG-RR-TY/114045590439

set of box wrenches including an 8mm which should fit in the tight hole indicated in the video (though this is only needed to split the casings):
https://www.ebay.co.uk/itm/7PC-BOX-SPANNER-SET-PLUMBERS-TUBULAR-NUT-WRENCH-MONOBLOC-6-17MM-TORQUE-BAR-20B/331623284582

cheapo ebay flywheel puller (requires additional bolts in order to be of any use (see below):
https://www.ebay.co.uk/itm/13-PIECE-HARMONIC-BALANCE-CRANKSHAFT-GEAR-PULLEY-PULLER-FLYWHEEL-BALANCER-TZ/324497829601

Additional/longer bolts needed to make the cheapo ebay flywheel puller work (get 3 of M8 x100mm ):
https://www.ebay.co.uk/itm/M8-8mm-PART-THREADED-BOLTS-HEX-HEXAGON-HEAD-SCREWS-STAINLESS-STEEL-DIN-931/383682199386?var=652081107590

#YZFR125 #BIKELIFE #BIKEWIFE

Yamaha YZF-R125

Making a new fuel map for bigger injector with PCV & Autotune, on yamaha YZFR125

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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 🙂

IF YOU’RE INTERESTED IN FUEL MAPPING:

Please check out this interview I did with DynoJet UK – we covered some really interesting ground – especially if you’re thinking of buying a Power Commander (who make the Power Commanders).

Yamaha YZF-R125

Winter updates

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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
Continue reading Winter updates →
Yamaha YZF-R125

How to convert PCV maps to PC3USB easily (and free)

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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

Yamaha YZF-R125

Autotune – game changer

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(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

Continue reading Autotune – game changer →
Yamaha YZF-R125

YZF-R125 injector swap

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So there’s been a few discussions on the forums recently about different injectors, and I happened to film when I swapped my injector over so figured it might be useful.

It’s a pretty straightforward process…as long as you don’t mess it up.

At which point it would become very complicated. So really don’t do that.

I have a theory – that on a stock R125 which has perhaps a slip-on ((or full exhaust) and a K+n filter, that a 120cc/min injector would make a really cheap, convenient upgrade.

When mine was tuned like that the fuel map was adding about 20% across much of the map. Not all of it but enough for it to potentially make a difference where it matters.

And here’s the link to the 120cc/min injector. As far as I’m aware stock is 100cc/min, so that would give you a 20% bump across the range.I’ll just leave this link here: https://www.aliexpress.com/item/32921…

My problem currently is that I don’t have a stock bike to test the idea on…though I’m hoping i’ve found a volunteer. Watch this space 🙂

YZF-R125 tuning, Stretching scooters, welding & fabrication, customising, custom parts.

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