Tag Archives: YZF-R125 tuner

My First Drag Racing Win on YZF-R125 @ Dakota Raceway

So whilst most of the day was everyone racing individually against the clock, they did have an optional “knockout” competition in the afternoon, where each bike has a handicap based on the times you’ve run so far.

This is 1/8mile (660ft) no-prep sprint racing on an airfield and my first time out racing on a bike.

So as far as I understood the rules: with this knockout thing if you’ve been running 10s and someone else has been running 8s, they’ll get a 2sec delay on the start and have to chase you down. If both bikes have a good run they should cross the finish at the same time.

So it lets mismatched bikes run sorta fairly, which is pretty neat. If you make any mistakes and the other guy doesn’t..you’re out.

The survivors of each round go into the next.

If you somehow run better than your best time so far, you knock yourself out, which is random but an interesting twist (similar to “bracket racing” i think).

I’d been running early 11s all day and the scooter I was racing was much faster, running 8s, and somehow despite my start I got there before he could chase me down 🙂

That was only the first round of the comp and I very much lost the next race, but hey. A win, ANY win first time out is a nice thing, so I’m happy 🙂

Bizarrely it was actually my slowest run of the day (11.6).

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This is on my gen1 (2008) YZF-R125, 180cc, still; on the PCV+autotune setup with the RPM limit raised to 11.5K on the OEM ECU.

#YZFR125 #YZFR125tuner #YZFR125racing #YZFR125sprint #northCust #NationalSprintAssociation

Northcust becomes UK/EU distributor for Tuneboss ECUs \o/

Ok so I’m quite excited about this. It’s been in the works for coming up to a year now but till we reached a particular point where we were both happy, I’ve had to keep things kinda under wraps.

Several years ago, sparked off by a conversation with Legend of Legend’s Garage (who used to do a fair bit of R125 stuff), I learned about Tuneboss ECUs, which seem to be quite popular in the R125 racing community (in europe anyway).

I got in touch with Tuneboss but since the previous ECUs were a limited run there were simply none to be had.

3 years pass and then I get an email asking if I’m still interested in buying a few ECUs. At the time I was just looking to buy 2 or 3, mostly for my own usage but perhaps for a few other friends if they were interested.

Either way, we got chatting and things escalated and whilst the UK/EU market is small compared to the Asian market, they wanted to have a presence here.

image shows an A4 plaque which reads "Tuneboss Authorized Distributor, UK & EU"
Continue reading Northcust becomes UK/EU distributor for Tuneboss ECUs \o/

First real sponsor!

So as you may or may not know, so far I’ve come up empty on what the current speed record for an R125 is, so I figured if there isn’t one, why not try to set one (with proof – pics or it didn’t happen!).

Even with many things in my favour, it turns out this is quite an expensive undertaking. It’s a long way to pretty much anywhere from Devon so fuel and entry fees are enough of a problem to be a problem, especially when trying to ensure a working bike too.

Hence – sponsors 🙂

"New Jersey Is a Lifestyle" - Business/Lifestyle directory for New Jersey, Sponsors top speed attempt on Yamaha YZF-R125 from UK tuner Northcust
Continue reading First real sponsor!

B-motor – 1200mile update

ok so we’re about 1200miles down on the rebuilt B-motor with rebalanced internals and right the way through break-in miles I felt like the clutch was slipping. I sorta expected this because on the previous motor it slipped from too much power so didn’t really think much of it. Every now and then it did seem to “catch” properly and would dig in and take off but it seemed to be random. For those times it happened though.. wow.

But then at the end of break-in miles since i had to change the oil anyway I put the upgraded clutch (R15 clutch basket with 6-spring boss + uprated springs) from the old engine and it still wasn’t quite hitting the speeds I was expecting. It would get to about 85mph but not any further and given this engine has the power band back in the correct place and screams from about 8.5k right thru the limiter this was unexpected behaviour.

I had been expecting the map to take a while to adapt to the new engine but really it ought to have done that by now. I had recently done a 2hrs each way run which was all main roads so we were in the 8-10.5k range most of that run which meant the autotune had plenty of time to do its thing and sort the map.

The other week I thought I’d just try it on the 14t front sprocket as a test and weirdly it was still not catching right…so I dug into it a bit more and discovered I’d put the clutch cable in a different position from how i’d had it before to see if i could lighten the pull, and then forgot I’d done that. It’s a 1 finger stunt clutch with 3 cable positions so you can vary the travel/pull-weight and as it turns out in the “lightest” position where I had it (which gives the least clutch movement) it was never fully engaging the clutch….

So then I switched it back to the middle position back to the somewhat heavier pull and holy chickenballs what an instant difference.

Continue reading B-motor – 1200mile update

The B-motor runs!!

woop! it runs \o/ (so far).

This has been a massive learning curve for me, particularly the sheer number of operations which have to be completed, as well as having to build at least 2 special tools to get the job done meant (for me anyway) it wasn’t really possible to “see” the whole process from start to finish, which in turn makes me very nervous on a project.

Continue reading The B-motor runs!!

YZF-R125 180cc “B-motor” engine build photo catchup

I started a thread on the forums a little while ago but meant to mirror it here. I may add in the old posts here if i get time but otherwise this will have to serve as a little photo-catchup. please refer to the forum thread for the full story. I’ll try and update both moving forwards..

Whilst not pictured here the cylinder and head are loosely on now while I set up the timing chain etc. Hopefully in the next few days it should be ready to fit.

[EDIT: pics updated, engine fitted and runs!]

Splitting the crankshaft on YZF-R125

Biting the bullet here and using the ebay hydraulic pless to separate the halves of the crankshaft and replace the con-rod etc. This is getting serious now..

Finding crankshaft balance factor on YZF-R125

going further down the crankshaft-rebuild rabbit-hole and getting on with the crankshaft rebuild for my new motor…

In this video we’re looking at trying to calculate the balance factor for the old 125cc setup vs with the big-bore kit, to see if that maybe explains why it’s run a little differently since going big-bore.

The logic is based on this video from 2StrokeStuffing (thank you!): https://www.youtube.com/watch?v=0hoE_…