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We just did the 1, that’s how the bike came from the dealer so that’s how we did it
We’re definitely going to do that
Yeah I didn’t crash haha happened close enough to the ground that I was alright
https://www.ebay.com/str/cmill987
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That’s him.
A buddy of mine does the part out business, but he didn’t have a 2-stroke 250/300 motor on his site.
for anyone else needing new/like new take-off parts, this is his eBay page as well. Great guy to deal with, he’s in Burbank, Ca. Alex
https://www.ebay.com/str/socalmotorecycling
Same piston and rod for carb, TPI and TBI so if the new piston had a skirt out of spec it could most def hit the crank. Counter balanced motors all pretty similar. There was pics of a TBI bike where the skirt hit the crank and the rod broke on the small end, split the part where the wrist pin goes through almost in half. There is a big cut out on the rod for lubrication of the wrist pin bearing which would make it a weak spot.
I don't know if he has the parts for OP's bike but here's the guy:
https://www.vitalmx.com/community/cmill987,61692/all#all
Edit: Checked his posts and it does not appear that he has 250 2 stroke parts.
Can consider buying the BRC 500 kit $6300 (www.BRCracing.ca in Canada), I believe you just need the donor transmission, kit includes cases, cylinder, etc.
Also Tom Morgan Racing does a good job weld repairing damaged cases, maybe a cheaper option than new, if not too wasted…
That is some ugly looking metal for such a new bike. Almost looks like it's crystallized.
I am anything but a motorbike tech, but there may have been some porosity in those castings. Otherwise, glad to hear that you are OK . Good Luck with the rebuild.
You said 100 hours on the frame does that mean bottom end also with pump gas?
Ready to race?
Yes
GasGas is actually #getonthegas but I guess I got on it too hard
Heads are cast, looks like a typical cast fracture.
Just scrolled through your guys site. It’s nice not scrolling through a bunch of old garbage.
These bikes love leaded fuel I would never go past 50 hours on the bottom end with Japanese two Strokes new to the KTMs not sure about the Austrian quality yet🤷♂️
Hong Kong Flu Got You...
Pit Row
Hydraulic lock?
Only 2t I’ve seen break everything- both cases, barrel and head, was a rod failure in a YZ125. But I have seen a few KTM’s crack/ break cylinder heads due to big end failures. Their outer casting around the insert is very thin.
Yes, I am aware of the common parts. However, the carb and TPI bikes went a solid 6-7 years on those parts with no common issue of skirt to crank contact. I've never heard one report of it. That issue did not begin until the TBI bikes came out. So, that makes us ask, what changed? Well, it's an all new cylinder to start with. Maybe something going on there. Also, the TBI bikes have a rev limiter. Maybe cutting the ignition or fuel on a two stroke at max rpm makes some weird things happen with piston vibrations or fluctuations?
I’m in the proses of doing the top end in my 23 300sx and when I checked the deck height it was 0. And that’s what the manual says. I haven’t checked the squish yet as it’s still apart but I will let you know what it is. As far as the parts. My dealer gave me a top end kit for a 2017 300xc. I was super skeptical at first but after some research pretty much any 250/300 crank and piston is the same since about 06 on. Even the gaskets are the same. The only difference in my cylinder compared to an old one is on the left side cover there is just a hole with a o ring in it to accept the servo motor. The rest of the covers are the same. I have heard the piston clearance issues but even both physical pistons have the same part number stamped in to them and physically look identical. I even checked the skirts with a caliper and they measure identical. If he has 100 hrs on a bottom end that’s not uncommon but failures can happen. If you blew the lower or upper rod bearing your gonna smash the piston in to the head and that’s likely what happened.
Are these bikes really fragile enough that you can expect a failure this severe if you put 100 hours on an engine? I have no idea how fast the OP is, but if he’s racing a Gas Gas 2 stroke, he ain’t qualifying for Supercross. In my 30+ years of racing, I’ve never rebuilt a crank before 100 hours no matter what brand of bike. I just put the first piston in my KX450 at 90 hours, and I mostly did it out of cold weather boredom.
I have done only 5-6 250/300 top ends, all were 2 stacked base gaskets to get required X dimension . Did you measure X ? Or maybe coolant leak into combustion chamber? Could be upper/ lower rod bearing or rod itself but 100 hrs on oem crank is usually not an issue unless a Pro is riding it.
I've always thought it was a good idea to rebuild the cranks before they fail not after to prevent this kind costly repair and also what possible injury could be caused from the bike locking up! They're all kinds of factors involved the riders speed his weight the terrain he rides in the weather how well is maintenance is! I might be a little excessive but I like the Peace of Mind that it brings LOL
Yes but when and for how long were pistons produced out of spec? Not trying to be stubborn but if it was my bike would def want to know why it came apart?
Any thoughts on how any bike could run for more than a minute with skirt to crank contact let alone 20+ hours?
Doesn't happen immediately. Typically happens when the bike is pushed hard. Its due to the inner intake skirt of the piston being to thick. Google it or search the 300 SX thread, its on there. I am not that skilled on the computer to find it and attach it to my post. Lol
I’ve seen this happen to 4 bikes I know off. 2 of them were under 20 hours…
and was told by a shop owner the new efi bikes do the same thing. It’s not you. Just a reoccurring issue.
Can't tell you how but they will. Sometimes forever. 2 Strokes are awesome.
Going to need to see the rest of the carnage to determine exact cause here. I can see a couple scenarios.
Post a reply to: Grenaded GasGas 2 Stroke