So my bike keeps topping out at 89mph at which point we’re still on power but bouncing off the limiter.
Today we’re attempting to fit another OEM ECU, but which has been tweaked to increase the rev limiter to 11k.
If it works, it should increase our potential top speed to around 96.7mph – which would be a significant improvement, and also makes me wonder whether 100mph might actually be possible.
Will it work though, or will it result in fiery engine death?
Only one way to find out…
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 updatewoop! 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!!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!]
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..
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_…
B-motor crankshaft rebuild progress in pictures…
what we’re starting with..
This is the second attempt at removing the lower timing gear and the captive bearing on the crankshaft of my spare “B-motor”, which I’m trying to build up for my bike.
Idk if this is how it’s supposed to be done but I’m working with what I’ve got.
Whether this turns out to be a good approach or not long term remains to be seen but for now let’s see how far we get with it…
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
