mynewcr250, on 14 April 2012 - 06:00 PM, said:

he's actually a cousin.  I had sold/finance the KTM to him awhile back but never got a dime.  So I confiscated the KTM but it was too late...the damage was already done.

Good work!! Some will say its a sinful job you did LOL. Report back in  a year or so and tell us how long it lasts. I would have went with a new piston. If it is loose in the bore it will slap around and break the skirt.

crap ! you're right ! I should have checked for piston/bore play before putting things together ! yes a new piston would have been better !


I'm wondering if some good synthetic oil will at least give me a hint before things exploding at some point?

by the way what's a good fuel mix ratio for this particular motor/bike?

I don't know what the manual recomends. But you really can't go wrong at 32/1. Its plenty of oil for most any 2 stroke. Oil will not save you from piston slap. Its basicly hammers the piston in the bore till it breaks. The piston rocks in the bore as it changes direction. It may or may not be an issue. If you measured the piston and the bore you would have an idea of how much clearance you have and what to expect. I saw some crosshatch in the cylinder bore so I doubt it was worn very much. But the piston deffintly lost material. Every engine is different and puts differnet stress and loads on parts. The KTM may have a very strong piston and a bore/stroke ratio or long skirt that doesn't rock the piston much.

I ran 50:1 in all five of the 380's I have had with no issues. 32:1 is very safe.
Joe........

thanks for the info guys.

by the way it's a 360 and not a 380...sorry.

good read.

Is this thing still alive?

To the OP, the crank is going to be just fine, the piston will sieze long before the crank and bearings suffer (and yes I'm speaking from experience) also the cylinder is OK, I wouldn't waste the time or money replating it. You might want to check at some point if the plating is flaking off, but I dought that will happen.

sinful, on 16 January 2012 - 10:43 AM, said:

triumph406, on 08 November 2012 - 12:44 PM, said:

Triumph, did you even read his original post?   You wouldn't replace the cylinder?  That's just crazy, hopefully this guy rebuilt the whole motor top to bottom. That's what it needed.

KTMRider4Life, on 08 November 2012 - 01:32 PM, said:

If I was on a budget, and reading the type of riding the OP did with the bike, no I wouldn't repair the cylinder, and the bottom end is definately OK, and if it isn't, it wasn't because it ran without oil.

If it was my bike, and knowing I could be a 100+ miles from my truck, then I would repair the cylinder, I do a lot of hours on my bike, so I would see it as insurance.

triumph406, on 09 November 2012 - 12:34 AM, said:

I doubt a bike with scuff marks all over the cylinder would run very well and it certainly wouldn't run for long. Just my humble opinion.

i ended up rebuilding the top end and $500-600 dls later the bike is still running so so.  falls flat at wide open throttle.  from idle to 1/2 throttle it runs okay.  might have to take apart the bottom end to replace those crank seals since I already tried jetting with little effect.

Edited by sinful, 10 November 2012 - 06:30 AM.

Enduro Chris, on 08 November 2012 - 10:57 AM, said:

yes it is !