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-   -   KTM125 mystery bag (http://www.dirtbikeworld.net/forum/showthread.php?t=123799)

clearasmud 14-12-2016 07:33 PM

KTM125 mystery bag
 
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I've picked up a 98 125sx that "went fine" and just stopped for no reason..

Diagnosis so far. Either the piston has been in there forever and decided enough was enough or it's hit the powervalve or both.. Thoughts ?

Rebuild 15-12-2016 09:19 AM

That's not mechanical damage, that's melted.
Maybe it was ridden without coolant?
Don't think it's detonation, as usually will have lot's of marking on crown too.

Check the bottom end for any movement up/down

How's the cylinder?

arrow 15-12-2016 03:29 PM

ran too lean or held wide open for 30km's, maybe crank seals have gone.

as Rebuild said that's not a mechanical fault that's gotten too hot or too lean and melted the crown of the piston off, they may have got the ignition timing wrong also

clearasmud 16-12-2016 11:00 AM

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Thanks for the input. Much appreciated. The cylinder had some black marks above the exhaust port but I've been able to clean most of it up so far with a honing wheel and a scour pad. No movement in the bottom end

RMJay84 16-12-2016 11:06 AM

would have gone well just before it stopped though

clearasmud 16-12-2016 11:59 AM

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To add some context here's the rest of it pre-tear down

arrow 16-12-2016 05:45 PM

hmmmm not one of Ando's old bikes? Castrol KTM was the factory team in Oz at the time I cant remember who the 125 rider was on the team. Craig Anderson was the head rider for them most of the time. Danny Anderson was with them too but I think later on.

I hope your not going to leave that bore in that condition before you put it together are you?

clearasmud 16-12-2016 11:09 PM

No. Will take it to get cleaned up properly after christmas when i start the restore properly, that was just a quick scrub.

clearasmud 04-01-2017 11:05 AM

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while im waiting for the piston to be delivered so i can send off the cylinder for a re-coat, i've hit the next challenge..
The upper shock bushing is knackered and I'm looking for a more economical alternative to the OEM one ( a lazy $197 for part 46811096s ), it doesn't look like all-balls make one. would this be a bearing shop item or am i stuffed ?

shawbagga 05-01-2017 12:26 PM

They're a spherical bearing I believe. Mite score em at bearing shop or could order one in. Maybe another brand crossover part(GG, husky, Yammy)


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