New MSO 140sr Midsize

Mini Dirt Bikes & Pit Bikes Forum

Help Support Mini Dirt Bikes & Pit Bikes Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
OK here's the specs

MSO140SR RRP $2495

Lifan 140cc big valve head motor with new design performance carburettor

Midsize chromoly frame with cradle and removable subframe alloy swingarm

New DNM MT-RC 1000lbs shock with compression and rebound adjustment

MSO Racing USD long travel forks with compression and rebound adjustment in each leg



Front suspension MSO Racing inverted forks, adjustable compression and rebound in each leg

Rear suspension Alloy swing arm, DNM MT RC shock with adjustable compression and rebound

Who is the original fork manufacturer?
Pretty sure MSO arent making their own forks so.......are they just re-stickered DNMs?
 
Hey Guys,

Waiting to be put through its paces

IMG_1060.jpg


Here's a shot of it in action

IMG_1183.jpg


Bye,
Linda
 
I rekon MSO should make a 50. anyone else agree?
Big time agree, Someone should make a 88 replica or just shuv a 140 into a chasis basicaly the same scale as a crf50 but have a decent chromoly frame thts based of the billetware cradle frame 1" longer. 10" rims , speed fork copies with a chromoly copy of the original crf swingarm.I would buy it straight away. This would be handy as due to I know a few kids that really want pitbikes but say they need to be smaller as the standard pitbike seat height is just smaller that their normal rides. Mso stop coming out with all these bloody amazing looking machines that make my x7r look about 10 years dated.
 
Bushy runnin in his new sr .... mine gets here tommorrow:D

bushywhip.jpg


Oh yeah Me Bushy and Durant are all about gettin em goin as well we can... they come ready to rock stock however we'll be workin em with some internal trickery for the sx

so I'll keep ya's in the loop.

Got a few more snaps but we had a kidding crosswind and only got the ramp out to 45ft... Bushy aint happy with photos if he's not doin at least 50 .lol

We gotta sort the track and get a run into it but he's lookin at a BIG 80ft to100ft stepup.
 
Veeeery happy

Ok threw mine together yesterday arvo with ya a BASIC pre ride check and took it for a ride....To say I'm happy would be an understatement, I was involved in the concept and production of this model and am proud to be throwin a leg over the end result....Well done Ken and Linda.
I'm very fastidious with my bikes so I'm strippin it down again today ...no need to but I like to set up my own bike and am never really happy until I've turned every screw ,nut and bolt....lol

but yeah it was good to go outta the box :D

Ok only had a 2 hour trail ride but the first thing was the ergo's and handling ..... I'm a big guy and have never been comfortable doin monos standin on a mini....

No worries on the SR I can pull em ALL DAY now :D
Handling is sick ...soooo much more ridable than a mini ...if you are over 6foot like me you wanna be on this bike....you ride it more like a big bike and it's far less twitchy...it went wherever I pointed it and I couldn't fault the brakes or suspension either.... like I said I only rode the trail loop on the property.... but I was around waaaay faster than the mini ....I was smoother ,faster and didn't need to work as much to do it ..:cool:

Thanx again Kenny and Linda sooooo STOKED :D
 
Over in this thread: http://www.miniriders.com.au/forum/minibike-reviews/15570-new-bike-opinions-please.html#post145922 I wrote about using 15wt Motorex oil in the MSO 140SR forks.

Well now I believe that 15wt Motorex is far too heavy. It might make the seals feel lovely, but what also happens is that it takes too long for the oil which has passed up the rebound dampening circuit to run back down into the "pool" of oil in the lower fork. So after continual use (eg. over very bumpy ground with no smooth sections) the dampers will run out of oil and cease dampening, because too much is still dribbling down the spring from the rebound circuit.

In other words if you have these forks, then (of course dump the fish oil holding all the as new metal filings then) try Motorex 7.5wt fork oil or the equiv viscosity in your favorite brand. I suspect 7.5 will be the ticket but I cannot be sure since this is trial and error. Of course the clickers will need to be wound in a little if you were previously happy with your dampening. I expect the seals and smoothness will still work just fine. Just use a very good fork oil which is anti-sticking, seal conditioning, anti-foaming, high temp stability, etc, etc. Actually if you are keen, then I still recommend a full flush out of the old oil and contaminants using some (cheap but genuine) 5wt fork oil.

I still believe that 275ml per leg is the magic volume of oil to prevent bottoming out - via the "compressed air spring" action. With a fork leg out of the bike and in your hands, it's reasonably easy compress it fully to approximately "feel" the minimum amount of oil. You can also compress it over and over like I did and feel if your dampers "air out" because your oil is too thick.

I will report back once I know more. But save yourself $25 and don't follow my earlier advice on 15wt and get 7.5 or 5wt instead. These forks (are "real" USD forks and) require significant oil movement and circulation.

btw: I've not looked yet, but would like to know where we can buy some nice ready made guides to attach fork legs to stop the fork guards from making scratchy noises as they rub on the stainless ring clip that goes around the lower end of the gold anodised tube.
 
Last edited:
I rode my 140SR mid size again yesterday. A lot of fun. I learned a few more things about the bike.

7.5wt fork fluid is good. Possibly could go to 5wt for real bumpy conditions. I used 275ml in each fork. I believe that for trails you can use more suspension travel via less fork fluid (less air-spring effect). And if you are not using all travel on the circuit/terrain being ridden on, then your setup is wrong. So in summary, I suspect that 250ml is about right for trails and 280ml would be safe/good for supercross.

I previous wrote about lowering the bike (forks in clamps and spring pre-load. Well for a hard packed track with berms and semi-flat turns that'd be fine. But yesterday in soft loamy dirt with deep ruts cut out by powerful big bikes, I needed more height - just so I could control my inside leg properly. So I put the forks full down and re-adjusted the rear (raised rear so the bike still turned in properly). If you wear full size boots and knee braces (which I like to), or you have long legs, then I suspect that a straight bar peg mount (if one existed) would be better by moving the pegs away from the seat a little, to enable an easy swing of you inside leg from out front to the peg and visa versa. In the ruts the front brake caliper was pushing some dirt, but no drama in softish soil, and not much I can do about it with a 14" front - unless I went to 17" (and a 14" rear) ... ?

I moved the short gear shifter up on the spline and assist getting full sized boots under the shifter. Worked great. Downside is I need to lift my leg a little more to down shift. Ideally need a longer shift lever. Stock is 105mm pin centre to centre. About 125mm would be better.

I fiddled with my dampening clickers with good results. I will write back later with numbers for my clickers and rear sag settings.

The engine ran fine. I have a 15:39 final gearing. Much better for me, since could ride our circuit in 2nd and 3rd and use 4th in the straight. I have the lightened oil slinger. Very noticable and good. I will try the IRK later.

The air filter is a problem in damp conditions. I am going investigate mounting a pod filter in the huge cavity under my seat, and running a duct from it to the carb inlet. Anyone tried this? We had to cross some creeks to get to our track and it (the filter) was a pain. I had to stop once and remove it and carefully wring it out. The creeks are up to 20m across, 8" deep water and with a semi quick-sand base. So you cannot go too fast (drench filter) or too slow (sink/bog).

The front Innova tyre felt okay on medium/soft ground with 12psi (and a rim lock). The rear doesn't seem to have enough traction (with 12psi too), but I have to try something different to put it into perspective.

The stock chain was given a workout with lots of WOT riding in soft terrain and often sandy. No noticeable chain stretch which is great! Nothing like the chain on my daughter's Atomik 70cc.
 
Last edited:
Update:

After the rut riding exercise described above, last night (in garage) I checked my clickers and I am on:

Compression: front = 9 out, shock = 8 out.
Rebound: front = 7 out, shock = 7 out.
These are ball park but possibly far from dialed in. Great to see plenty of adjustment range left and bike handles reasonably good thus far.

That is with the 7.5wt fork fluid and 275ml of it. I also have the 800 lbs/in rear spring (I am 73kg). The 800 rear spring so far is fine for 73kg me. I can only guess that many people probably run a stiffer spring in minis as a (wrong) way to get the bike to turn into corners. The downside would then be horribly bad traction accelerating out of corners. And of course a woefully rough jarring ride. I admit need to do more testing for sure.

btw: I tried some 5wt fork fluid in one leg as an experiment, and not only was it worse, the basic action felt terrible! Really amazed me. There was an air sucking type sound in a valve or dampers, and no amount of use could make it go away. So back to 7.5wt (motorex) and all smooth again. ;) Keen to hear what other owners try and find in these forks.

Ques1: Anyone yet replaced their seat foam with something firmer?? The stock seat foam is very soft! :confused: The effective seat height when riding corners drops by about 4cm at a guess. Huge problem and possible gains.

Ques2: Is there a taller 1st gear cog to be bought cheap anywhere which drops straight into the Lifan 140 case?
 
Last edited:
Suspension closer to dialed in now. Cornering quite well. Railing most ruts, tight or long, or banked or off camber, with a full brake approach then wide open throttle usually at around the apex. Normally don't need to steer the bike much on a typical rut exit. The bike responds well to suspension clicker adjustment, and as usual the front vs rear height adjustment makes a huge diff and needs tweaking for different tracks. Here are my settings for other 140SR owners:

Forks: Oil Motorex 7.5wt 280ml. Clamps with 2mm fork leg exposed at top (near full down). Compression = 9 or 10 clicks out. Rebound = 6 or 7 clicks out.
Rear: Static sag = 35mm. Rider (73kg) sag = 75mm. Spring = 800. Compression = 10 or 11 clicks. Rebound = 4 clicks.

I find that with any less fork rebound than 6, then front wheel can (or will) push wide in poor traction turns. Any less rear rebound dampening, and the rear is like a poegoe stick on braking bumps.

OKO26mm carb is working great. Inlet ports matched/aligned. Unifilter intake. Screw = 1.5 out, Slow = #38, needle = mid, main = #100. But the float level HAD to be raised else the engine bogs with no fuel on fast flat corners with the bike laid over for a second or more. Fuel line is flowing freely.

I have an Akunar race CDI and coil. To be honest I changed so much on the carb side, and went to a diff track, so I cannot rate the ignition changes on their own. Certainly the engine pulls great. Maybe the ignition is advanced a little since kick back on starting is a small problem.

Pirelli MX Scorpion rear tyre is unreal on loamy dirt. I am going to put my heavy steel oil slinger back on, because I think my bike will be faster for me on most technical tracks. I am tired of using clutch on 3/4 of turns to keep the correct drive at the rear wheel. Much better for kick starting too.

Worst thing about the bike for me, is that the 1st gear in the Lifan 140 is way too low and the 2,3,4 gears are wide apart ratios. I can somewhat work around it via changing final chain drive gearing, but this only works for some tracks. If the Lifan 140 had a close ratio 4 speed, then IMO it'd be heaps better for MX and SX, but I guess Lifan have many other uses for this engine. Cannot complain. Just need to keep fanning that clutch.
 
Last edited:
Update:

OKO26 carbie (non-standard item): Great. Very snappy of torquey power in low and mid revs. Sensitive to air conditions. In less humid conditions I had to go one clip richer (than middle) on the needle, and also back to the richer 102 main jet. See also: http://www.miniriders.com.au/forum/tech-talk/16320-needle-position-lifan-140-a.html#post153171

Suspension rear: Shock (DNM) is going in for a re-valve. On rough tracks, engine HP is fine at present, and the shock is the limiting factor when accelerating or braking in bumps. I played with the clickers but I could not find a good compromise. The problems with the DNM shock are: a) The dampening is not progressive according to where shock is in its stroke. b) The shock's dampening is inconsistent as it heats up, so the rear ends becomes a bit unpredictable. I shall get this fixed by a tuner.

Suspension forks: I am now using 290ml of 7.5wt fluid in each fork leg. For more bottoming resistance. The forks really need a re-valve too - for serious racers. eg. I can add oil to stop bottoming, but the top of the stroke then hardens up too much as well. I can use thicker 10wt oil and the action feels nicer, but on repeated bumps the oil cannot flow through the rebound circuit quick enough to re-pool down the bottom. With thinner 5wt oil the valving sees to "air out" or cavitate. Don't read me wrong. These forks are excellent value. I'd love to feel the diff against best retailed Marzocchi's or Fastace forks.

Race CDI. Died on me. So back to std. Easier starting with stock CDI. Race CDI did seem to have a little more go at high revs, but nothing substantial. The race CDI was causing too much starting kick back - probably because it was a dud unit and/or the wiring on my bike has a problem which that unit did not like.

Cam: I have an Akunar A1 6.7 mm lift cam. Not installed it yet. This coming weekend is my last chance to ride before I go away (work) for a few weeks. Also got an A2 cam being sent to me now. I had a peek at the stock cam grind, and the A1 is similar in style but more duration and lift. It'll be interesting. On rough tracks a strong bottom end engine is great on this bike. A LOT of fun.

Oil slinger: I tried the steel one again. I cannot go back to the steel unit again. It kills the accel. So alum slinger for ever on the Lifan 140 for me. If my crank breaks due to fatigue flexing and the lack of weight on one end (no IRK), then so be it. I'd rather the joy of faster engine spin up, and buy a new motor if I kill it. There is no point revving this engine a lot (troque drops off), so I guess I'll be fine with the alum slinger.

Tyres: I put a Kenda Millville on the front 14" wheel. On medium hard surfaces, I'd say the Innova had more traction. The problem with the Innova is that the tyre carcas is 6mm smaller all over than the Millville, so less tyre body/air/pressure support on impacts the rim can be dented easy with the Innova tyre on rough tracks. The Millville grip on medium/hard terrain is not good IMO, but it will do for now.

Air filter "snorkle": Working great! See also: http://www.miniriders.com.au/forum/tech-talk/15882-air-intake-snorkle-2.html#post153170

Next: Forever learning how to ride it faster. Firmer seat foam. Shorter turn throttle grip.
 
Last edited:
Cheers bruz you are all over it ..thanks for the tips and keep up the good work.
 
Thanks Dreadful. All is not rosie though ...

On Sat I tried to install my A1 cam. The good news is that the A1 is a monster compared with the stocker. Not measured the lift, but if the A1 is 6.7mm lift then my stocker looks like only about 5mm.

The bad news is: Put the cam in. With the supplied springs. Verified cam sprocket at 9 o'clock and flywheel 'T' at 12 o'clock. Gently turned engine over by hand. Felt just a little stiff but I figured that was normal valve train resistance. No so. Now a hissing (horn like) sound comes out the inlet valve (tappet cover off and ear near it). So I've probably bent a valve. Will pull it apart on Wednesday and order new parts.

Not complaining. I put the head on using a 0.5mm alum gasket whick lost me maybe 0.4mm. But I did not do the play-doh clearance check thing. Yeah stupid I know. I rushed it. If anyone can advise on the valve/piston clearance check process then I am keen to learn. My guess is that to be real pedantic/safe I have to check one valve at a time, with the head nuts torqued down, and reverse rotate out of the stroke being tested and disassemble and check+dremel.

No big deal. Just a bummer, no more 140SR for about 4 weeks for me. :(
 
Last edited:

Latest posts

Back
Top