MTX 125 questions

[FFMan]

I'm getting an MTX125 via a friend that I haven't seen. Its cheap and was a runner when they put it away a few years ago. It needs some fettling but should be basically sound though its an older model I suspect, though they say it has 7k miles on it.

I'm a biker and spanner handy but new to 2 strokes mostly so:-

1) what 2 stroke oil for it, mineral, semi or synthetic
2) trust the auto-lube or mix it myself
3) how often does it need a piston and rings ?
4) any known issues to be aware of ?
5) recommended steps to re-commission (carb strip & clean, cooling system flush, new plug, brake check, tyre check)
6) does this engine have any reed valves etc to check/replace

I've bought a Haynes manual off ebay for some reading but experience from other owners counts for a lot, so any help appreciated.

thanks

[Suntan Sid]

1) what 2 stroke oil for it, mineral, semi or synthetic

Any, but synthetic cannot be mixed with mineral, drain tank and fill with either or.

2) trust the auto-lube or mix it myself

Check and bleed pump, if it's working use the autolube.

3) how often does it need a piston and rings ?

Shouldn't need them after 7k, if it hasn't been abused

4) any known issues to be aware of ?

Replace all bearings and bushes on suspension, they'll be fooked on a bike that age. If the compression is down you may need to look at the crankcase seals.

5) recommended steps to re-commission (carb strip & clean, cooling system flush, new plug, brake check, tyre check)

Should do the trick

6) does this engine have any reed valves etc to check/replace

The Haynes should tell you!
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"Everybody needs money, that's why they call it money!"

[bikenut]

read the manual and study cmnsl for the exploded views.........

ENGINE......

the clutch will be stuck and needs a gentle approach to free it off, unless you want to remove it and clean it manually, best options as if done the other way, the rust etc ends up in the gearbox oil and bearings etc.

its liquid cooled and has a thermostate, which may also be stuck.

remove the plastic flywheel cover and check for main bearing play....have come across some with seized main bearings flywheel side, which have rotated in the c/case ( the outer race ) and ruined the engine.

steady as you go, bit by bit, don't rush and be methodical.

drain the gearbox oil, any water/metal flakes/particles come out??

read the manual for ign, charging, lub and fuel........
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nuts about bikes

[FFMan]

clutch is seized - now I have a clutch cable its obvious

is it easy to dismantle - I have a Haynes

[stirlinggaz]

[bikenut]

:karma:

you know of cmnsl for the exploded views which will help.........

you will see the "special" slotted nuts for the crank and clutch drum.... 2 different sizes from memory......

also the fine thread left hand threaded flywheel puller is a MUST!!

good luck taking the head cover off, its on 2 dowels and the spark plug "tower" spigot and seal....see cmnsl exploded views.......

take your time and enjoy...........

any flywheel up and down play??
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nuts about bikes

[FFMan]

ok - got the r/hand cover off ok then ran out of time.

I guess if the clutch is seized I just need to remove the clutch basket and free the rings up, or replace if really seized. Looks clean inside and oil was fresh.

I'll need the 4 tooth tool to remove the clutch (make or buy off ebay), but as I don't need to remove the flywheel not the other special tool.

Will the rings just be a bit stuck and able to come apart ?

[Rogerborg]

[FFMan]

so the clutch was stuck on, so I removed the clutch basket but all seemed cleaned and loose in there.

Reassembled it and it now works, even rode it down the drive so its nearly fully recommisioned.

TBH front caliper was the most difficult bit and front master was toast so has an aftermarket one which seems to work just fine.

Seems to be a slight weep from the 2 stroke tank but it stops soon after running.

maybe next weekend i'll take it down the field for a blast.