Help me understand this engine blowup.....

MxKing809
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MxKing809
Edited Date/Time 4/27/2021 5:33pm
2019 KTM 150

- 11.2 hours on the entire bike
- 45 minutes on a Wiesco GP piston
- Running 50/50 110 leaded and 93 pump gas
- Riding in Michigan, weather was 50 degrees and sunny
- Jetting is richer than stock, running Motorex premix at 32:1

Went out for a moto and made it 10 minutes before a seize.

A fellow rider thinks it was a cold seize because I didn't run a radiator block to keep the engine running at optimal Temps.

What say you?







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SeaClassExpert 4/25/2021 5:50pm
4/25/2021 5:50pm
My money would be sucking dirt but I'm a big idiot so take that with a grain of salt.
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BobPA
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BobPA 4/25/2021 5:54pm
4/25/2021 5:54pm
What was the piston to cylinder wall clearance? Forged pistons always like a little more wiggle room in the bore. Looks like the bore was too tight to me.
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kb228
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kb228 4/25/2021 5:56pm
4/25/2021 5:56pm
The bike is orange
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gerg
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gerg 4/25/2021 6:00pm
4/25/2021 6:00pm
OOOOOOOOOOOOHHHHHHHHHHHHHHHH !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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scott_nz 4/25/2021 6:03pm
4/25/2021 6:03pm
BobPA wrote:
What was the piston to cylinder wall clearance? Forged pistons always like a little more wiggle room in the bore. Looks like the bore was too...
What was the piston to cylinder wall clearance? Forged pistons always like a little more wiggle room in the bore. Looks like the bore was too tight to me.
This. And forged piston normally require more warm up which may have not helped ,
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DerickYZ
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DerickYZ 4/25/2021 6:04pm
4/25/2021 6:04pm
Looks like the piston to cylinder wall clearance was too tight. As BobPA mentioned, I agree as well.
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BobPA
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BobPA 4/25/2021 6:06pm
4/25/2021 6:06pm
BobPA wrote:
What was the piston to cylinder wall clearance? Forged pistons always like a little more wiggle room in the bore. Looks like the bore was too...
What was the piston to cylinder wall clearance? Forged pistons always like a little more wiggle room in the bore. Looks like the bore was too tight to me.
scott_nz wrote:
This. And forged piston normally require more warm up which may have not helped ,
100%. I cannot stress this enough when people install Wiseco's. You can hear them audibly rattle when the engine is first started.
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JWACK
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JWACK 4/25/2021 6:11pm
4/25/2021 6:11pm
kb228 wrote:
The bike is orange
No it’s not.
MxKing809
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MxKing809 4/25/2021 6:11pm
4/25/2021 6:11pm Edited Date/Time 4/26/2021 7:36pm
BobPA wrote:
What was the piston to cylinder wall clearance? Forged pistons always like a little more wiggle room in the bore. Looks like the bore was too...
What was the piston to cylinder wall clearance? Forged pistons always like a little more wiggle room in the bore. Looks like the bore was too tight to me.
scott_nz wrote:
This. And forged piston normally require more warm up which may have not helped ,
BobPA wrote:
100%. I cannot stress this enough when people install Wiseco's. You can hear them audibly rattle when the engine is first started.
Hard to tell for sure why it happened.

Bike was warm and ran for 45 minutes before this happened. Would think something would have popped sooner.
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joe stanley
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joe stanley 4/25/2021 6:19pm
4/25/2021 6:19pm
I’ve run Wiseco pistons for years in a wide range of weather temps. Ice riding to summer motos. The key with forged pistons is a good warm up before riding hard. Otherwise they do what yours did......
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Jaybird67k
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Jaybird67k 4/25/2021 6:20pm
4/25/2021 6:20pm
I agree with piston to cylinder clearance but I wanna know why was the piston being changed to begin with.
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scott_nz 4/25/2021 6:20pm
4/25/2021 6:20pm Edited Date/Time 4/25/2021 6:21pm
MxKing809 wrote:
Hard to tell for sure why it happened.

Bike was warm and ran for 45 minutes before this happened. Would think something would have popped sooner.
I have never been a fan of two stroke forged pistons for this reason , but to be fair to Wiesco , they offer a huge range of sizes but few people measure their bore before ordering the right one
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AZRider
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AZRider 4/25/2021 6:21pm
4/25/2021 6:21pm
MxKing809 wrote:
2019 KTM 150 - 11.2 hours on the entire bike - 45 minutes on a Wiesco GP piston - Running 50/50 110 leaded and 93 pump...
2019 KTM 150

- 11.2 hours on the entire bike
- 45 minutes on a Wiesco GP piston
- Running 50/50 110 leaded and 93 pump gas
- Riding in Michigan, weather was 50 degrees and sunny
- Jetting is richer than stock, running Motorex premix at 32:1

Went out for a moto and made it 10 minutes before a seize.

A fellow rider thinks it was a cold seize because I didn't run a radiator block to keep the engine running at optimal Temps.

What say you?







Not saying its wrong, but why are you running a wiseco piston in a bike with only 11.2 hours? unless you are racing at a very high level, the stock piston should have still been fine. Just a question. Call me an idiot, as I am sure many will... and yes, looks too tight.
14
BobPA
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BobPA 4/25/2021 6:22pm
4/25/2021 6:22pm
scott_nz wrote:
This. And forged piston normally require more warm up which may have not helped ,
BobPA wrote:
100%. I cannot stress this enough when people install Wiseco's. You can hear them audibly rattle when the engine is first started.
MxKing809 wrote:
Hard to tell for sure why it happened.

Bike was warm and ran for 45 minutes before this happened. Would think something would have popped sooner.
All bore sizes are a bit different, it is on the installer to check for proper clearance. Why do you think you send the piston out when you have a cylinder plated.

I have used Wiseco pistons in numerous different engine styles, and never had any trouble.
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sandman768
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sandman768 4/25/2021 6:25pm
4/25/2021 6:25pm
If it were a cold seizure, wouldn’t it be a 4 corner seizure? I’m just chiming in to learn... why did you replace the stock piston at 11hrs?
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MxKing809
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MxKing809 4/25/2021 6:26pm
4/25/2021 6:26pm
MxKing809 wrote:
2019 KTM 150 - 11.2 hours on the entire bike - 45 minutes on a Wiesco GP piston - Running 50/50 110 leaded and 93 pump...
2019 KTM 150

- 11.2 hours on the entire bike
- 45 minutes on a Wiesco GP piston
- Running 50/50 110 leaded and 93 pump gas
- Riding in Michigan, weather was 50 degrees and sunny
- Jetting is richer than stock, running Motorex premix at 32:1

Went out for a moto and made it 10 minutes before a seize.

A fellow rider thinks it was a cold seize because I didn't run a radiator block to keep the engine running at optimal Temps.

What say you?







AZRider wrote:
Not saying its wrong, but why are you running a wiseco piston in a bike with only 11.2 hours? unless you are racing at a very...
Not saying its wrong, but why are you running a wiseco piston in a bike with only 11.2 hours? unless you are racing at a very high level, the stock piston should have still been fine. Just a question. Call me an idiot, as I am sure many will... and yes, looks too tight.
I'm 200 lbs and not very easy on the bike..... figured I'd rebuild it this winter before the season instead of half way though.
Brad460
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Brad460 4/25/2021 6:26pm
4/25/2021 6:26pm
Why 110 leaded mixed with 93 pump? Are you running higher compression ratio?
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joe stanley
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joe stanley 4/25/2021 6:27pm
4/25/2021 6:27pm
It is also why OEM 2 stroke pistons are cast.
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AZRider
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AZRider 4/25/2021 6:33pm
4/25/2021 6:33pm
MxKing809 wrote:
2019 KTM 150 - 11.2 hours on the entire bike - 45 minutes on a Wiesco GP piston - Running 50/50 110 leaded and 93 pump...
2019 KTM 150

- 11.2 hours on the entire bike
- 45 minutes on a Wiesco GP piston
- Running 50/50 110 leaded and 93 pump gas
- Riding in Michigan, weather was 50 degrees and sunny
- Jetting is richer than stock, running Motorex premix at 32:1

Went out for a moto and made it 10 minutes before a seize.

A fellow rider thinks it was a cold seize because I didn't run a radiator block to keep the engine running at optimal Temps.

What say you?







AZRider wrote:
Not saying its wrong, but why are you running a wiseco piston in a bike with only 11.2 hours? unless you are racing at a very...
Not saying its wrong, but why are you running a wiseco piston in a bike with only 11.2 hours? unless you are racing at a very high level, the stock piston should have still been fine. Just a question. Call me an idiot, as I am sure many will... and yes, looks too tight.
MxKing809 wrote:
I'm 200 lbs and not very easy on the bike..... figured I'd rebuild it this winter before the season instead of half way though.
I'm 180lbs and change my piston every 25 hours in my 150. Use vertex and each time the piston still looks great. 2018 Bike has 104 hours. Faster than most
2
Kyle978
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Kyle978 4/25/2021 6:36pm
4/25/2021 6:36pm
Not sure about your specific scenario, but I’ve never had good luck with Wiseco 2-stroke pistons.

These days, I just replace with OEM as I no longer have a need for mod motors. Seems to alleviate a lot of headaches.
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BobPA
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BobPA 4/25/2021 6:40pm
4/25/2021 6:40pm
sandman768 wrote:
If it were a cold seizure, wouldn’t it be a 4 corner seizure? I’m just chiming in to learn... why did you replace the stock piston...
If it were a cold seizure, wouldn’t it be a 4 corner seizure? I’m just chiming in to learn... why did you replace the stock piston at 11hrs?
Typically yes, but not always. This seizure is really tough to tell 100% of what caused it. Looking at pictures, and seeing the piston in real life are two different things haha. I would almost certainly bet that this was caused by the piston to cylinder wall being too tight.
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Rickyisms 4/25/2021 6:42pm
4/25/2021 6:42pm
Check your bore measurements for sure. I agree with sandman on debating a cold seizure, forged pistons definitely like being nice and warm before a moderate to heavily load is applied to the engine. I’ve always stuck with the vertex cast replacements and have never had a problem.
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Rickyisms 4/25/2021 6:43pm
4/25/2021 6:43pm
Brad460 wrote:
Why 110 leaded mixed with 93 pump? Are you running higher compression ratio?
In my experience with a stock KTM 125 and 150 motor the 110 mixed in gives it slightly better throttle response and two strokes like their lead.
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sandman768
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sandman768 4/25/2021 6:59pm
4/25/2021 6:59pm Edited Date/Time 4/25/2021 7:05pm
What is wiseco”s recommended piston to cylinder wall clearance? Was ring end gap checked? I have a 93Cr125 with an original B cylinder. I ordered the smallest OD ProX piston for it, sliding the piston in the cylinder without rings, it felt tight, I was not comfortable with it, so I brought it to a machine shop to have the piston to cylinder clearance checked. Sure enough, the piston was too big. I had to find an oem Honda B piston for the cylinder.
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dcg141
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dcg141 4/25/2021 7:15pm
4/25/2021 7:15pm
That's metal to metal so no dirt involved. Lube failure, clearance issue or the nikasil failed from the previous piston.
inthebadboycorner 4/25/2021 7:22pm
4/25/2021 7:22pm
Hi, as you did not mention it, we could assume the old piston looked great?

Do the oem cylinders still have the ink stamp A, B or C to indicate oem piston size?
yak651
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yak651 4/25/2021 7:46pm
4/25/2021 7:46pm
Say no to weisco...stick with OEM, philosophy has treated me well over the years. Don’t blame you for putting a new one in at 11 hours. 15 max for a 125 and like you said, might as well do it during the off season even if it’s a bit early
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yak651
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yak651 4/25/2021 7:48pm
4/25/2021 7:48pm
For those saying cold seize, wouldn’t that happen before 10 minutes of riding? I always figures a cold seize is from getting on it right away before bike warms up. I don’t know, just trying to learn.
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fullfloater 4/25/2021 7:52pm
4/25/2021 7:52pm
Maybe you're just too fast for a 150 MxKing809? Wink
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KurtJ99
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KurtJ99 4/25/2021 8:02pm
4/25/2021 8:02pm
I thought modern two smokes were Nikasil plated.
It may have gone 10 min before a sieze but been have been on its way during those 10min. That’s a lot of metal scraping it didn’t happen in 1sec.
I had an iron sleeve ‘85 bored real tight 1.8 thou and I took it straight to a race with no break in after a bore. Seized up, but after 5-10 min.
Rather than cold sieze, is it possible your radiator fluid was low after piston replacement and you hot siezed?
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