Changing front sprocket on yamaha yzf-r125

This is me trying to do a walkthrough of changing the front/drive sprocket on a Yamaha YZF-R125 without a rear wheel stand/paddock stand.

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YZF-R125 Handlebar risers vs clutch cable

So when I did the handlebars conversion and made up the new clutch cable, I kept it following the OEM design where it has a corner just before going into the clutch lever assembly…like so:

On the left you can see the 90 degree elbow..

For whatever reason, that doesn’t really seem to work too well on the new setup. This was something I only discovered when trying to learn to pop wheelies the other day…

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POWER COMMANDER V Map switching Test run & topspeed on the 13:48 gearing

This is just a quick video to test how well the gopro clone footage comes out on Youtube. Hopefully it doesn’t mash it up too bad.

In this run I’m testing out the map switching function on the Power Commander V, having just hooked that up (more on that soon), and also there’s a top speed run to see what the max speed it could reach was, on the 13:48 gearing (13 tooth front sprocket, 48 tooth rear).

This is part of my ongoing testing and tuning of my 125.

fitting clip-on handlebar risers to the YZF R125

I’ve got a prior back injury which means the leaned over position of the R125 can be a bit much on longer journeys, and over christmas I’d been commuting on the bike every day and my shoulders weren’t getting a break so was constantly aching, not ideal. So I’d been wondering about the possibility of fitting some clip-on risers for a slightly more upright position.

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Preparing the yzf-r125 for Winter riding, and Further adventures

So the last few months have been pretty tough on a personal level so I haven’t really had much time to lavish on playing with bikes, plus I broke the car so the R125 has been more about getting me from A to B in all weathers, which much to my delight it did really well.

The little bits of workshop time I’ve had have been mostly focussed on just keeping everything running as best as I can, again, which despite adversity, worked. I have however still been working on things and have a backlog of photos etc which will probably turn into a bunch of posts, of which this is the first.

After the car broke last october (which was supposed to be my winter vehicle) I decided not to sink any more money into it and double down on the 125 instead, however insane that sounded going into what was supposed to be a potentially serious winter. But hey whatever, YOLO

Continue reading Preparing the yzf-r125 for Winter riding, and Further adventures

Baffled – Part 3

So I found this thread which possibly explains what’s going on with my exhaust (2nd post particularly relevant).

i think this may be about gas velocity, which would sorta explain the current counter-intuitive performance improvement by adding the baffle in the can. I’ve also realised that it might be better still if i take the forward baffle out (the one which came with the exhaust system) and only have the rear one…that way i might get better performance still and regain some of the nice sound.

It may also do nothing/make it slower in which case it’s going back how it was….gonna find out today hopefully.

Continue reading Baffled – Part 3

Baffled – Part 2

I did another quick run across town just now with the baffle in and it definitely seems quicker. I dunno if that’s because I’m less conscious of the rpm and so ride differently but it definitely felt like it wanted to *go* again. Much grinning when I got home. 

I guess it’s possible that at low/mid rpm the little bit of restriction might improve torque somehow – I guess there’s sound waves and stuff going on in there to some extent like a 2-stroke. I didn’t really get chance to go flat out though and that’s where I’d expect the baffle to be a restriction…will have to see. Didn’t seem to be a problem revving high at speeds up to 50ish though, kept finding i had to back off a bit.

I’m still not loving the sound but stealth is better and obviously whatever’s quicker wins. Interested to see how it does on a test run. I guess I need to figure out some sort of timing malarkey I can work with gloves on first, though even just seeing how it performs when flat out with the baffle would be interesting. Next time she’s on the dyno I guess we’ll find out for sure but that won’t be for a while yet.


I did a little test run today, primarily wanting to put some miles on the new tyres…unexpected results in other areas tho.

A couple of months ago when I got the PCV fitted and bike tuned I also got them to put a 15t sprocket on the front since I’d kept bouncing off the gearing up until then and was looking for better cruising rpm (e.g. so I can cruise at 70ish over longer distances without revving like a twat the whole way). which is fine, but it meant I’d never had a direct comparison with before/after tune on the original gearing.

In the spirit of seeing just how good my “mud and snow” rated winter tyres are, I’m wanting to do some “local exploring” where I’d likely be wanting acceleration over top end so I put the 14t back on to test. Also for exploring a degree of stealth may be beneficial so I put the baffle in the end of the can (which I’ve also never tested properly). Without the baffle “stealthy” is definitely not a quality it has.

Continue reading Baffled!

Some possibly interesting motorbike & car projects

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