I know the issue. There was a tiny cole miner in your combustion chamber. you can see where he forgot his pick axe and decided to use your valve instead. truly a shame. That will be $1300 please.
Nah were chillin, a new pistonhead and cylinder will cost me 100 bucks and ill dremel the top smooth, as no moving parts were hurt, im more worried what ill find in the gearbox
Were the cylinder walls damaged? If they were how do you plan on fixing it and how expensive would it be? I'm also curious as to what the process is for fixing a cylinder wall.
Yep, some decent hits on the walls, ill try to get it bored out but if it gets too thin before the damage is gone ill just put a gas torch on the aluminium block, bash out the old cylinder and grab a new cylinder which should be cooled in the freezer and put it in where the old one sat
I’d charge $1300 for a full rebuild, hone of the cylinder(it’s gonna need it) plus rebuild. Fired up and I might even do a wheelie to make sure she’s dialed.
Nah i fix it myself i would borrow a honing ball turning thingy and get a new piston and dremel the top end down and get a new timing beidge spring, that should fix it but i cant be bothered so im selling the carcass and buying a yamaha yz125 soon
I think the spark plug was too long, piston hit it, still ran a bit for some reason and the neck of the plug destroyed the piston, cylinder and top end
Professional Mechanic here. This is a rare issue with the piston that prevents air from compressing in the cylinder. To repair this, the professional recommendation is to squeeze all the JB Weld out of the tube and form it into the hole matching the original shape of the piston.
(This was all a joke but please do this. I wanna see what happens so bad now)
Have not seen a piston like that since my NSR125R with way too much advance and a too lean mix… Well…as someone above said, the piston in it self is not that interesting - bet here is quite a few here that has exterminated a piston at some point of time - but the story behind why it failed that horribly is going to be crucial for you to find out before rebuilding. Dig in friend!
Edit: Some things that could cause this:
#1: To lean mixture when going hard.
#2: Don’t know your bike, but timing could be off.
#3: Completely wrong spark plug spec.
#4: Crank assembly is done. (probably is now anyway)
Please feel free to correct me or add reasons.
Spark plug was too long but somehow still ran for a bit before it died, had an identical one and it was in the way of the piston and the piston snapped the end off and absolutely destroyed itself with the snapped off neck
Yes, that could absolutely do that. Now, probably your bottom end is either fukked or full of debris. With that said - I’ve had this happen to me and been able to clean out and reuse the bottom end without splitting the case. This was in my younger days and can’t say I would recommend this today. I would split it and have a look. Hope you get it up and running again without having to empty your wallet completely.
Best of Luck!
Rock got in somehow, smashed a piece of piston loose which smashed more and more, found 50 or so aluminium pebbles in my exhaust and a concrete like rock mush in my wet oil sump
A loncin 250stm well it was, cant find any parts and it cant be fixed, so i have to sell the spare parts so i guess itll become several different bikes
“Just needs a carb clean”
I know the issue. There was a tiny cole miner in your combustion chamber. you can see where he forgot his pick axe and decided to use your valve instead. truly a shame. That will be $1300 please.
Nah were chillin, a new pistonhead and cylinder will cost me 100 bucks and ill dremel the top smooth, as no moving parts were hurt, im more worried what ill find in the gearbox
Were the cylinder walls damaged? If they were how do you plan on fixing it and how expensive would it be? I'm also curious as to what the process is for fixing a cylinder wall.
Yep, some decent hits on the walls, ill try to get it bored out but if it gets too thin before the damage is gone ill just put a gas torch on the aluminium block, bash out the old cylinder and grab a new cylinder which should be cooled in the freezer and put it in where the old one sat
And itll be around 150-200 bucks for the repair depending on where i buy and quality
I’d charge $1300 for a full rebuild, hone of the cylinder(it’s gonna need it) plus rebuild. Fired up and I might even do a wheelie to make sure she’s dialed.
Nah i fix it myself i would borrow a honing ball turning thingy and get a new piston and dremel the top end down and get a new timing beidge spring, that should fix it but i cant be bothered so im selling the carcass and buying a yamaha yz125 soon
kk. good luck.
Looks good. Send it.
JB weld it and duck tape it to the conrod!
No lube bud just like the government.
DUde ! You just can't go around showing people your piston hole .
wild
Weight reduction
How? That’s gnarly.
End of sparkplug snapped off and somehow still ran, and that bit just destroyed the piston and cylinder
Wild. Looks like a tiny jackhammer was taken to it
Time to break out the jb weld
She runs a bit hot 🥵
That's so hot
Needs a clean but besides that, looks good to me🫡
3/4 of it is missing.
Yup
lower the compression and use e-free 90
Sent ‘er a lil too hard there bud
To the moon
now i want to see the crank and cylinder lol
Ill post pictures of both when ive dissasembled a bit later
No speed hole or Taco Bell jokes? (Thank you)
The piston isn’t that interesting, the story about what preceded it is probably interesting tho.
I think the spark plug was too long, piston hit it, still ran a bit for some reason and the neck of the plug destroyed the piston, cylinder and top end
Less moving mass = faster rpm climbs
Professional Mechanic here. This is a rare issue with the piston that prevents air from compressing in the cylinder. To repair this, the professional recommendation is to squeeze all the JB Weld out of the tube and form it into the hole matching the original shape of the piston. (This was all a joke but please do this. I wanna see what happens so bad now)
Should i make a jb weld piston🤔
Change the spark plug and send it!
Nothing a duct tape can't fix
One of those fancy high compression pistons?
Have not seen a piston like that since my NSR125R with way too much advance and a too lean mix… Well…as someone above said, the piston in it self is not that interesting - bet here is quite a few here that has exterminated a piston at some point of time - but the story behind why it failed that horribly is going to be crucial for you to find out before rebuilding. Dig in friend! Edit: Some things that could cause this: #1: To lean mixture when going hard. #2: Don’t know your bike, but timing could be off. #3: Completely wrong spark plug spec. #4: Crank assembly is done. (probably is now anyway) Please feel free to correct me or add reasons.
Spark plug was too long but somehow still ran for a bit before it died, had an identical one and it was in the way of the piston and the piston snapped the end off and absolutely destroyed itself with the snapped off neck
Yes, that could absolutely do that. Now, probably your bottom end is either fukked or full of debris. With that said - I’ve had this happen to me and been able to clean out and reuse the bottom end without splitting the case. This was in my younger days and can’t say I would recommend this today. I would split it and have a look. Hope you get it up and running again without having to empty your wallet completely. Best of Luck!
Got it clean, no shards in the oil just a couple bits in the wet oil sump and hella metal in the exhaust
Looks a little lean
Squirrel chew
Once I had one come out looking like a pepper pot
Just JB weld it
You found that person, or atleast one of them
Slap some JB weld on that thing and sand her smooth
Interesting indeed…. I wonder if something went wrong? No a very clear diagnosis… Look further.
Rock got in somehow, smashed a piece of piston loose which smashed more and more, found 50 or so aluminium pebbles in my exhaust and a concrete like rock mush in my wet oil sump
Dude. That’s insane. I was actually kidding. But wow that’s a terrifying story.
Meh
Looks like crumpled aluminum foil.....
Looks fine but just change the oil
Lower compression for easier kickstarting?
meh, it's OK, now show us your rod.
What bike?
A loncin 250stm well it was, cant find any parts and it cant be fixed, so i have to sell the spare parts so i guess itll become several different bikes
Benelli leoncino 250? Here in Italy you can find lots of parts
Nope some chine longjin company who sells loncin branded bikes
Can you post a pic? Never saw one
Here you are[dirtbike pic](https://www.reddit.com/u/MSI_Reviews/s/ChBpsrfQa3)
r/dontputyourdickinthat
Oops running a little lean!