125-200cc WR125 re-visted again

Ive had few WR125s in the past and have been a long time member here. Ive been riding other bigger bikes but couldnt stay away and picked up another 2013 Wr125 a couple of months ago.
I thought Id share my recent experiences getting back into a smaller bike again

Bike was a low hours bike owner by an older gent (even older than me)

I rode and it felt pretty ordinary . Big bog and weak power but ok at top .
It was all orginal and still on its original piston.
Played with the power valve arm - didnt do anything .
Richened the needle height that helped a bit.
Put the RM needle in with a #5 slide and put on an old 39mm Mikuni I had with the RB designs divider plate mod and hey - now we are talking .. Big power increase in the middle to top end .
Jetting 460 main with 40 pilot . I would possibly try 470 main but dont have one .
Put a new piston and rings ( Id say 10 hrs old ) in with a .3mm base gasket and now its feels great.
Compression was down at around 120 and now at around 155

Felt it was maybe a tad rich down low and tried a 32.5 pilot and still pulls well. Less spooge.

Had quite a few rides and really loving this bike .
The top end power is surprisingly strong - even though I've had wr125s, 144s , 165s .
I love the feel of 125 motor size. Its sounds great and gets a lot of comments.
The handling is just fantastic . I really feel so confident on it and that means I ride it a lot faster in the tighter tracks than say the ktm 350 , fe450 or te250 2t , wr300 I have been riding .
The steering is so good and I can push it in the corners much harder. So much fun.
Ive put a stiffer rear spring on and all it really needs now is possibly shorter gearing - say a 52 rear.
I will post any other big improvements .

The weak spot with the standard needle seems to be mid range - if you are happy with it then thats good. I might try standard needle/slide again with bigger carb to compare.
I carry a bit more weight than you so I need to make as much power/torque as I can

The 52 may allow me to run in 2nd gear up some hills which is always better for momentum . 1st will spin up too easily . The only concern if you do need to use 1st from the start of the hill its a bit too low. Cant get speed needed that longer first does .

You have a great bike there. I've had three of them myself. Excellent platform and rock solid.

Looks like a wonderful motorcycle you picked up.

I’ve recently been riding my ‘12 WR144 after a long while letting it sit since I purchased a Beta 300 Xtrainer. These are wonderful bikes: handle great, decent low fir a small bore, and rip up in rpm’s. Makes me smile just to see it in garage, let alone ride.

Just gave some love: swingarm bearings & new sprockets & chain. After 100 hours on ring & piston compression is still 150.

Amsoil at 50:1.

Ive been running Maxima Caster oil - cos it smells nice haha. Got to leave those 4 strokes behind me something to nice smell. Seems to spooge quite a bit at 35 to 40 to 1 . But I dont mind it . I dont think Amsoil is available here

I am tossing up whether to put a CR ignition on it that I have been storing for 6 years or so . I kind of like how it feels now .

I have a used pro circuit works pipe & silencer that I bought off of another member on here but never did get on my CR before I sold it if yore interested?

Yeh possibly - I will PM you
Ive found the standard pipes are good and silencer also for trail riding

Ive just fitted some V4r reeds - will see how they go

I am looking at fitting a Hydraulic clutch kit .

I also have a couple of stock pipes for these if you ever need one.

I have pm'd you Walt .

I am also looking for another 125 cylinder, piston and head

I used a Magura kit on mine. Had a slave crap out on me once but has been pretty solid otherwise. Super smooth and easy pull with the Midwest lever.

I fitted some Vforce 4r reeds . Cant really say there was any noticeable improvement
Repacked the silencer and that was worthwhile .
Ive had a few issues with getting flat rear tyres. May try tubliss on this next .
Ive been riding the 450 today and Im worn out so I am keen to get the 125 ready for the next ride

I got another Wr125 which I traded for a crappy '09 310 so Ive got two WR125s to play with.
This bike was well used but fully rebuilt a couple of years ago by a friend of mine before he sold it to others. It hadnt done much work since - just changed hands a couple of times.

It had been a bit neglected and I could tell straight away it needed the silencer repacking and swapping silencers transformed the bike . Feels a lot smoother and free revving . More torque and power .







I am actually a bit surprised as this bike is standard with original carbie and needle . My other one has the 39mm RB designs carb with the RM needle but doesnt feel as strong up top .
Could be just a fresher top end.

I changed the ignition on this second bike to a CR ignition set up that I had from 6? years ago . I was surprised that it was easier than I remember last time .

The bike does feel more alive with that CR ignition . I couldnt fit the flywheel weight yet as the bolt needs to be modified or it will not fit.

I noticed a loss in top end performance. It seems to hit a wall. I might need to play with the position of the stator. But I think this is how it is . More mid hit but less top end .
I swapped to the RB designs carb and needle and it didnt help performance up top .

Id probably switch back to the WR if I ride it on trails.


Riding my original bike again I am going to look at the Power valve setting again and compare as it seems to have more of soft mid range than the other bike. Its flat in the middle and then hitting hard up top. Could be just the weight of the flywheel. I will also check the compression as well.
Might need to get a different PV spring.

I wouldnt mid getting some new white plastics and sticker kit - Pic of this recent bike when it had been done up a couple of years ago - HOT