MZ/MuZ Riders

i picked up this 2001 or 2002 bike a while back, and its been collecting dust while i got around to looking at it.
i'm told that it had oil changed and inspected about a year prior to me buying it.
the odometer shows 381 miles.

when i originaly started it, i noticed that:

1) it refused to start unless i severly restricted the air filter intake undet the seat.

2) once started, i had to keep the throttle open a tad before it warmed (?) up enough to keep on running. probably a couple of minutes into it running.

3) soon after it was warm enough to idle on its own i noticed a chemical smell and 'solder like' smoke coming from somewhere around the radioator.

at that point i shut it off.

fast forward to today.
i removed the right tank fairing and tried to trace for possible leaks.
i found that the coolant level is not at the cap level as speced for by the owner manual, but seems to be just under the the rows of metal inside the radioator tank.
i noticed that a small hose that comes out form the side of the top cap came off the nozzle and probably misses a clamp. i traced it all the way and it seems to be just a ventilation hose that end downward at the bottom of the engine.

Q1: is it necessary to drain the coolant all together before replacing it? or can i just top it off?
Q2: does it make a difference what kind of coolant i use?
Q3: could the chemical burn smell and the solder-like smoke trail be explained by the cooolant seeping out at the top and burning off the radiator's exterior?
Q4: is the large fan on the back of the radiator supposed to start spinning once the engine is started?

Coolant - it would be a good idea to drain the old coolant, (its really simple to do, cap off of radiator, undo large hose to crankcase and vent screw on second radiatior, it then pours out, did it myself the weekend, takes 15 minutes tops).
As you do not know what type the coolant is, its not a good idea to mix it, unless you just use water! (that works sometimes)

I use the coolant that is ready mixed (pink cheap stuff from Halfords, thats if you are in the UK) really need to use the one that is marked for aluminium engines.
Smell could be the coolant or a repair to the radiator if it gets really hot. But it may also just be the exhaust bedding in.
The large fan is connected to the thermostat and therefore should only kick in when needed, i have not seen mine go round in the 6 months i've had mine.

Hope this helps

Jamie

thanks for the replies guys public and pivate. i got the supplies yesterday and will try fixing the hose, and dealing with the coolant and starter this weekend.

also very encouraging to see the muz.de site back and fronting their 125 line.
maybe finding parts wont be as bad as i feared, and this steal of a purchase will be even better than i imagined.

will update with my progress

there a very nice ride
treat it good
and fix it right when it breaks
it will run well for you
keep in mind it may be a while before we can get new ones in the usa again
dave

Ok. got the vent hose clamped off and sorted.
topped off the coolant with some destilled water as it needed very very little it turned out. i intend to flush it and replace it a new later.

i started up the bike by covering the air intake as before, and held the thorttle slightly open to warm it up as i mentioned earlier.
i noticed that despite me holding the throttle firm and steady, the engine was making a sound as if it was revving up and then revving down.
it did this up and down up and down, is this normal?

a little while into the warm up, the coolant vent hose started dripping steadily.
while i was trying to confirm that it was the coolant hose and not something else, i let the throttle go slightly and the engine stalled.
why would the coolant drip so steadily?
was it because the bike was stationary and not getting enough air flow?
could heavy outdoor humidity play a role?

i had some trouble starting up the engine after, this despite closing off the air.

from the manual i read about idling speed adjustment screw.
and it says 'with the engine warmed up and running, turn the screw one way or another to reach 1800rpm'
Does anyone know if whether clockwise turn increases or decreases speed or vice versa?
Since the bike does not have a tachometer, how is this expected to be adjustable?

also, the fact that closing off the air intake is the only way to get the engine started, does that mean its getting more air than it should?
is this adjustable, or is there likely an air leak somewhere?

your carb is full of crap and all throttle idle screws i have seen turn clockwise to increase idle
fuel air mix screw in bottom of carb it turned out 1,5 to 2turns i set mine at 1 and 3/4
and made a safety wire so it could not fall out
idle speed at 1800 will sound fast idle at 2000 will sound way to fast
1500 to 1750 it will want to die all the time
dave

Gratz, OSPRNG, on resuscitating a 125 SM!

First and foremost, make sure to clean the carb. As Dave said, it's likely full of crap and could be leading to the poor idle performance. Also, keep tabs on the carb for air leaks. Be sure not to tear that rubber boot between the carb and engine, as it is a moderately pricey part to replace. Be sure to lube all your cables, so a snot to be dealing with a sticky choke cable.

For the radiator leak, it could be a couple of things going on. Look on eBay for a replacement radiator cap- it's a pretty standard KTM replacement (note the "KTM" stamped on the side of your raadiator?), and a new one should be obtainable for $15, if you are lucky. Forget the dealership on this one, as they want some incredibly high price for the cap. Also, check the sparkplug to determine if you are running lean. Finally, I'd also recommend checking your thermostat performance. This would be an ideal activity while you are replacing your coolant. Oh, and one more thing- there is a small hose connecting the two radiators, that runs across the "spine" of the frame. This hose easily gets kinked by the gas tank. Check for that, and get a standard replacement from a local radiator shop (again, cheaper than getting it from the dealership!).

Let us know also if there are any other mods to the bike. New pipe, carb, or timing advance, that may impact the engine behavior.

some corrections about the bike:
its definitely 2002, not 2001. paperwork had both numbers in various places, but title says 2002.
i misread the odometer, it is actually 38.1 kilometers (not 381 miles)
on 10/3/07 its logged to have had the carburator cleaned, a spark plug, and oil replaced.
it was stored with fuel stabilizer in the tank, which is probably why i was able to start it in the first place.
since the stabilizer was there all along, could the carburator still be gunked up?
someone told me a long time ago that if youre able to start the engine and let it run for a while, whatever gunk is in the carb gets cleared out by simply running.
is that inaccurate?

now on to some good news and some bad news.

the good:
i resolved the starting problems by adjusting the throttle lever cable.
it now starts with a simple button press and no airflow tricks.

the bad:
the dripping continued but since it was coming through the (now secured) vent hose i waited to see if it was just some excess, and would slow down and go away on its own.
a couple of minutes into it it actually did stop, but resumed elsewhere, up the frame.
i traced this up to another hose, which i think is the one that Drew is talking about:


i removed the tank and it didnt look like the tank had any effect on the hose at all.
only thing that i'm not sure about whethere the crack was there earlier today, or if it was created from some kind of pressure in the few minutes that i kept the engine running.

there are no hardware stores open here on sunday so i'll try replacing the hose tomorrow and go from there.

thanks for the help guys. for as long as the engine was running i have to say it was a pretty purr.
cant wait to ride this thing already..

Good idea to clean the carb just in case, you can get a carb cleaning fluid.
Best way is to take it off, (if you are confident of doing it) and take it too a friendly garage and ask them to put an airline on it, that helps.
The radiator hose looks as though it just perished, doubt if it would have built up that much pressure in just a few minutes running from cold.
My engine was a sod to start but once it goes it purrs like a kitten, and it now starts first time every time and they are a lovely bike to ride.

Jamie

sounds good. i'll tackle carb maintenence when i have this more of less runable so i can at least take it to the garabe for some look over and inspection.

more good news. i was able to stop all the leaks by replacing hoses and clamps. unfortunately i overforced one of the clamps that it tends to unclamp from vibrations. plan to pick up a replacement tomorrow.

when i got the engine to start with ease by unscrewing the throttle cable out more, i wondered if the sounds was a little too loud and runnig too rapidly, but then i watched some SM 125 soundchecks videos on youtube and i guess theyre OK.

i was planign to take it for a spin this weekend but looks like its goignt to be rainning heavily. so will wait till next week.

two things i'm considering: lowering the bike - is tightenign the tension spring the only way? i dont want to overtighten it.


also, on the topic of RPMs, the manul says to keep the idle at aroudn 1800, but i'm confused as to how the mechanic is supposed to be abel to tell it since there is no tachometer on the bike. is there some tool or is it chceked by sound?

whats a decent instrument replacemtn/computer?
i wonder if replacing the built in speedo/indicator box with something more featured would be a good idea.

finally took it out for a spin around the block.

seems to ride ok at first, untill i tried to make a tight right turn. the engine revved high and the bike sped up.
mild turn corrects left/ right are ok.. but all the way to the right it seems to increasethe throttle, all the way to the left seems to drop it a bit.

to me this seems to mean tha the throttle cable is being affected bu the steering, but i'm not sure exactly what is the right remedy.

is this something common with motorcycles? what sthe best way to secure the throttle cable to prevent this from happening?

edit: i came across this http://en.allexperts.com/q/Motorcycle-R ... able-2.htm which makes total sense.

question now is, what IS the correct way to route the throttle cable on the 125 sm?

currently, it and the clutch cable both run along the right side of the 'spine' of the frame. they are not attache din anyway, except towards the bottom they go under the side part of the frame and straight into the carburator.
as per manual these cables shoudl not be secured to the frame in anyway to keep the movemnt free. so how do i keeo t free. yet prevent it from sliding laterally when the steering is all to the right?

throttle cable is hooking or catching on something
maybe gas tank is binding it when its put on
and raising the carb slide with the cable is not proper
idle screw should control idle

and a comment about the assembly of bikes
when i bought my rt 125 bike in 2002 i brought it home and started in inspecting every thing on it
to learn all about it
i found plastic tie wraps pulled way to tight all over the bike
the wires to the rear turn signals were routed in a manner that left them stretched so tight
you could play music notes on them like a guitar
clutch was not adjusted throttle not adjusted
but i just bought a used 660 travller with 5825 miles on it that less than 500miles a year
and it was the same way i have put 1275 miles on it sorting it out
maybe this is why it had 4 owners before i got it
june 15th 09 to sept 1 and it now runs ok
factory's and dealers have a problem finding qualified help
soap box stowed under work bench
dave

I will have a look at mine as soon as i get time, but i am pretty sure the throttle is cable tied to the frame in a couple of places. I may be wrong but I will double check.

Its a common fault on motorcross bikes, had it happen on a couple of suzuki's, re routing the cable stops it happening, or a longer throttle cable.

Jamie

Thanks Jamie.

David, what you say about our bikes makes sense to me because the people i bought the bike from complained it had throttle problems that they could never figure out. the amazingly low mileage on a 2002 bike also seems to back up the theory of poor assembly.

with the tank off last night, i could see that the cables were not obstructed in any way, except for the frame section right above the carburetor where they are snug next to each other, but not kinked. as i move the steering to the right, the cables move freely, but to the extreme right, the stiffness of the cable makes it want to slide laterally, backward along the frame towards the carburetor, which seems to simulate slackness of the throttle, adding gas.

the only way i can imagine stopping it from sliding like that, is to secure it against the frame under the tank with something grippy, maybe a piece of rubber under a ziptie. though i'm still curious to hear how Jamie's cables are routed to see if theres a better way.

I am sure i have read somewhere that there was a factory modification of the addition of a zip tie under the tank.
I will see if i can find that as well.

Jamie