TL;DR: Top speed I’ve managed (so far) on mine with 180cc kit, 160cc injector and longer duration cam, with PCV + Autotune/wideband: 89mph.
So I’ve noticed there’s people searching on this topic so I’ll share what I’ve discovered so far, hopefully it’s of some use.
Top speed on mine when I got it, as 125cc on stock 14t sprocket was 83mph (indicated). That was absolutely throwing-it-down-a-hill-with-the-wind-behind-you, the most I could get out of it. 83 seems to be a fairly common top speed for stock bikes. Some other people have claimed 86 out of a stock bike but I can’t verify that myself and that wasn’t my experience.
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.
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.
I’m not sure why exactly I’m motivated to do this but I really want to learn how to wheelie and drift my bike. I’ve always been into drifting cars but somehow had never considered drifting bikes, probably because it’s kinda insane and dangerous as activities go.
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! 😀
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…
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.
