dakh

Mine didn't get better with the second change and then the clutch started slipping, I'm guessing from the metal shavings getting into it. I took it back to the dealer and they weren't able to make any progress on it for 6 months. I gave up and I'm getting an electric KTM freeride.. Not the same thing but I expect better manufacturer support than this POS.

Lots of metal flake in the oil and magnetic drain plug got a ball of the stuff on it, never seen anything that intense. Anyone done first oil change yet and had it look better?

Hmm.. I can't order this from US (EU only). It does use cylindrical cells (which is a lot less scary than pouch cells) but they don't say where those come from, which means we're back to "only charge and store in the fireplace" type deal. Useful bits of data on the peak and steady amperage though, 50A and 150A. So the batteries I was considering might be not enough.

Ah got it, so I need to be careful what the peak current BMS is going to support. Not sure what that number would be. On the 20A version of the one I linked to it says "Max. Permanent Discharge Current: 80A 10Sec".

I'm not willing to risk with LiPo and don't really want to geek out on stuff or have some super fancy setup. Any problem with just buying 3 of these and running in a 3s setup and then either charging as 3s or having a separate connector to charge them individually? I might go for 20AH version too, spendy but I like the idea of having tons of range. https://www.amazon.com/ExpertPower-Lithium-Rechargeable-2500-7000-lifetime/dp/B07X3Y3LS5?th=1 They look like they got a good BMS in them so I'm thinking if I charge them as-is (3s) with enough voltage they'll be fine, no?

Update: put a new (well, rebuilt by Millenium Tech) cylinder and piston on, bike started right up. I had kill switch disconnected (while I was messing around trying to understand why it doesn't run) so right away I had a chance to practice choking it. Shop towel up the exhaust pipe or a shoe trying to block it would not kill the bike, not even close. So I think my algo if this crap happens again is to just put it in gear and release the clutch. Maybe not drop it to not do any damage but act quick and get it done.

Ring gaps look to be in the right place (it's the back of the cylinder), it was just enough piston material that obliterated the ring -- I scraped it off with a knife and it's as expected. Cylinder is definitely toast too, the scrape that is above the port maybe can be cleaned up and honed out but there's a good chunk of coating (nicasil?) missing below the port that I uncovered after I scraped some of the aluminum. Maybe it was an imperfection in the cylinder to begin with. But looking at the exhaust side of the piston, it has perceptible scrapes all along the surface so this thing just ran way too hot. At least the crank and rod look Ok, no play at all. Should I send this cylinder to Millenium or someone like that or just get a new one? Good source for pistons? One more thing, while the bike was parked it weeped a bit of coolant. I could not trace where it came from. Took the water pump out and it looks all good to me. Is that maybe expected or should I try to maybe pressure test the cooling system? It didn't leak anymore so I'm not able to reproduce it. Radiator with no cap that would blow pressure off freaks me out a bit, if it got so hot maybe there's damage that I'm not able to see? Thanks!

Sorry for lack of updates, had limited time to work on bikes and had to dedicate all of it to keeping my enduro bike going. Finally took a look at this pos Contact ES. Turned out I have left hand thread flywheel puller but needed a right hand so waiting on that to show up to see if the flywheel got spun. Pulled exhaust and then had to pull the head off and now need to pull cylinder off to see if the crank is dead too. Sorry my terminology might be off, I know my 4-stroke Honda CRFs in and out but clueless on 2-strokes. Head looks good. So I'm now wondering did it spin fast enough while in the "diesel" mode to do this damage or it was some manufacturing defect that was there all along? And also still how do I prevent it from doing this trick again.

Got it, thank you. Good to know! Was your case also runaway diesel when running out of gas or some other way you managed to get the key snapped? What was the remedy -- just a new key or you had to get a new flywheel too? I'm assuming crank end is the toughest part in the whole deal. Ah what the heck I need to stop posting and open it up and take a look.

I screwed around with it for a bit without opening anything up. Drained 3 charges of the battery trying to start it in various conditions, removed the spark plug a bunch of times etc. No go. It will backfire pretty good once in a while but not even trying to run. Will try to pull the flywheel this weekend and see if I snapped the key. Called the dealer though and they said flywheel moving isn't common. Maybe I just have some junk stuck in the carb that produced the initial problem to begin with.

It appears that maybe the bike is just flooded, or it's flooded in addition to whatever else is wrong with it. I pulled the tank off and checked the throttle cable, I can see now how the cable housing would pull out of the metal piple that goes into the top of the carb and stay perched on its edge. It may or may not have happened, but yea bad design, the piece of the pipe where the cable housing is going into is just too short/shallow to be sure it won't come out. I did the whole throttle wide open and kick it a bunch of times deal with fuel off and it backfired pretty good on me a few times. Pulled the plug and it was wet, even though it was a new one I just put in (after the runaway episode). So I'm leaving it overnight with the plug out to dry. This is my second 2-stroke, all my other bikes are 4-stroke (Honda CRFs) and the first one was a KTM 200exc that never flooded to the point of not starting like this.

Thinking about this, even if the throttle somehow got stuck open this would not explain it. It would not have revved past the rev limiter and would have stopped with the stop button and definitely with the plug wire pulled wouldn't it? Or it was first the throttle cable got out of line and then by virtue of it running for a few seconds like that it started to self-ignite? Turns out I probably have the right flywheel puller so should be able to test the sheared key theory pretty easily. Anyone knows what years TXT I should be looking up parts for on this 2017 Contact ES? TIA!

Yes that makes a lot of sense, thanks! Now to hunt down the right flywheel puller... What can be done to prevent the throttle sleeve to pull out and get stuck? Maybe go around the joint with some tape?

Thanks for all the replies! Looking a big grim though... I don't think there's anything wrong with the throttle mechanism, but will check the slide position. It snaps back good and was snapping back fine as it was "running away". Engine seems to have very good compression still. Can you explain the flywheel key shear theory a bit more? I don't see how would that explain the runaway, or how would the runaway shear it if that is what the theory is. If it currently has spark (it does), that means the flywheel is still spinning together with the crank isn't it? So far I found one guy who had this happen on a txt280, same thing still ran at high RPM with spark plug wire pulled. Same thing had to kill it with the clutch. Also was running out of gas so seems lean condition was involved in both cases. His did restart after that just fine though.

Hi folks, First post and a question, I know somewhat lame but I got a pretty strange thing going, hoping this is some kind of a known issue.. I got this 2017 Contact ES, for a girlfriend, that decided later she can't hack dirt bike riding after all, so I figured what the heck, let me go ride it myself. The bike is essentially new, maybe 2 hours run time. I go with my usual riding buddies to Walker, carry 2 extra 750ml bottles of premix. After adjusting to it for the first half hour, I'm starting to giggle and have a ball picking the most gnarly line I can see and still making it.. After a while I go up this rooty ledge and all of a sudden the darn thing just starts revving to the moon. I get spooked, stop, put it in neutral and try to see if I have a stuck throttle. Doesn't appear to be the case. I hit the kill switch. No, still screaming its nuts off. Pull the spark plug wire. No effect, still screaming! My buddy has caught up to me and is looking at this **** in disbelief. I click a few gears up and drop the clutch, it stalls. Ugh. Ok. Some coolant leaked out, not that much but noticeable. Wiggled some wires, waited a bit for it to cool off, nope, won't start. Wiggled some more wires, tried to start it a bunch of times, it seemed to want to catch a little here and there but definitely no go. So I had a dead engine race down the mountain, brought it home. Pulled the spark pug, it looked perfect, and has spark. But won't start still. So first, if it ran for maybe half a minute in this "runaway mode", do I need to now be concerned with internal engine damage? Second, what's a good sequence for figuring out why won't it run again? Third, how do I prevent this from happening again? I'm planning to call a dealer when they open but not sure if this would be something covered under warranty.