Kx450f motor destroyed

imoto34
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imoto34 10/23/2018 3:10pm
10/23/2018 3:10pm
The fact that the guy wont honor that after 20 minutes is pure bullshit and you should be paying him a visit.
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project racer 10/23/2018 3:18pm
10/23/2018 3:18pm
Salvage what you can. Take the rest, and toss it through the mechanic's front window.
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newmann
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newmann 10/23/2018 5:35pm
10/23/2018 5:35pm
imoto34 wrote:
The fact that the guy wont honor that after 20 minutes is pure bullshit and you should be paying him a visit.
Question is, what is the mechanic supposed to honor if no one knows what happened? Guessing OP tore it down himself? I would have insisted the engine guy tear it down and offer to pay a tear down fee to find out what happened. Engine builder may not owe him anything but he’ll never win a customer over by telling him to pound sand with zero offer to look into the issue.
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kb228
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kb228 10/23/2018 8:08pm
10/23/2018 8:08pm
imoto34 wrote:
The fact that the guy wont honor that after 20 minutes is pure bullshit and you should be paying him a visit.
newmann wrote:
Question is, what is the mechanic supposed to honor if no one knows what happened? Guessing OP tore it down himself? I would have insisted the...
Question is, what is the mechanic supposed to honor if no one knows what happened? Guessing OP tore it down himself? I would have insisted the engine guy tear it down and offer to pay a tear down fee to find out what happened. Engine builder may not owe him anything but he’ll never win a customer over by telling him to pound sand with zero offer to look into the issue.
The mechanic should have found other worn parts and assembled it correctly so it doesnt blow up. Thats his job.

The Shop

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newmann
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newmann 10/24/2018 3:51am
10/24/2018 3:51am
imoto34 wrote:
The fact that the guy wont honor that after 20 minutes is pure bullshit and you should be paying him a visit.
newmann wrote:
Question is, what is the mechanic supposed to honor if no one knows what happened? Guessing OP tore it down himself? I would have insisted the...
Question is, what is the mechanic supposed to honor if no one knows what happened? Guessing OP tore it down himself? I would have insisted the engine guy tear it down and offer to pay a tear down fee to find out what happened. Engine builder may not owe him anything but he’ll never win a customer over by telling him to pound sand with zero offer to look into the issue.
kb228 wrote:
The mechanic should have found other worn parts and assembled it correctly so it doesnt blow up. Thats his job.
OP already stated that no bolt was dropped into the engine during assembly.

OP already stated the piston was replaced, supposedly with an OEM part.

What other worn parts should the mechanic have found while freshening up a 25 hour top end on a 450? Should crankshaft assembly replacement be considered routine maintenance at 25 hours on a 450? That's where I would probably call bullshit and be looking for another builder...Wink

Until someone convinces me otherwise with information not already provided in this thread, I still see a massive piston failure.
c0ncEpT
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c0ncEpT 10/24/2018 6:06am
10/24/2018 6:06am
I think that the rod snapped just below the small end. The piston came down and hit the crank breaking the one pin boss and denting the other. Ripping whats was left of the pin/rod out in the process.

I don't know how you can think that the pin/rod came out of the piston while still attached the the crank when the small end of the rod looks brand new. If that were the case one one think there would be severe damage to the small end as it slung around and smashed the cylinder wall.
kb228
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kb228 10/24/2018 6:40am
10/24/2018 6:40am
newmann wrote:
Question is, what is the mechanic supposed to honor if no one knows what happened? Guessing OP tore it down himself? I would have insisted the...
Question is, what is the mechanic supposed to honor if no one knows what happened? Guessing OP tore it down himself? I would have insisted the engine guy tear it down and offer to pay a tear down fee to find out what happened. Engine builder may not owe him anything but he’ll never win a customer over by telling him to pound sand with zero offer to look into the issue.
kb228 wrote:
The mechanic should have found other worn parts and assembled it correctly so it doesnt blow up. Thats his job.
newmann wrote:
OP already stated that no bolt was dropped into the engine during assembly. OP already stated the piston was replaced, supposedly with an OEM part. What...
OP already stated that no bolt was dropped into the engine during assembly.

OP already stated the piston was replaced, supposedly with an OEM part.

What other worn parts should the mechanic have found while freshening up a 25 hour top end on a 450? Should crankshaft assembly replacement be considered routine maintenance at 25 hours on a 450? That's where I would probably call bullshit and be looking for another builder...Wink

Until someone convinces me otherwise with information not already provided in this thread, I still see a massive piston failure.
Kawasaki themselves say to check the crank every 15 hours. You should be checking the crank every time youre in there anyways. Replacement is unlikely but you never know. If we use that logic, pistons shouldnt be breaking at first startup either. Realisticly the mechanic could have not used assembly lube on the cylinder walls and it bound up.
c0ncEpT
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c0ncEpT 10/24/2018 7:40am
10/24/2018 7:40am
c0ncEpT wrote:
I think that the rod snapped just below the small end. The piston came down and hit the crank breaking the one pin boss and denting...
I think that the rod snapped just below the small end. The piston came down and hit the crank breaking the one pin boss and denting the other. Ripping whats was left of the pin/rod out in the process.

I don't know how you can think that the pin/rod came out of the piston while still attached the the crank when the small end of the rod looks brand new. If that were the case one one think there would be severe damage to the small end as it slung around and smashed the cylinder wall.
Thinking about it a little more I can see a scenario where the piston fails 1st.

If the 1 pin boss started to fail and pulls the pin out, The piston could have started to cock in the bore which is what snapped the rod.

newmann
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newmann 10/24/2018 7:50am
10/24/2018 7:50am Edited Date/Time 10/24/2018 7:52am
c0ncEpT wrote:
I think that the rod snapped just below the small end. The piston came down and hit the crank breaking the one pin boss and denting...
I think that the rod snapped just below the small end. The piston came down and hit the crank breaking the one pin boss and denting the other. Ripping whats was left of the pin/rod out in the process.

I don't know how you can think that the pin/rod came out of the piston while still attached the the crank when the small end of the rod looks brand new. If that were the case one one think there would be severe damage to the small end as it slung around and smashed the cylinder wall.
Nowhere in any of OP's posts did he mention that the pin or small end that he is holding in his hand actually fell out of the piston and were bouncing around in the engine. Again, from the few pics he posted I still think the piston failed and caused the rod to snap off when the pin dropped out of that one side. The other side of the piston looks a little egg shaped in the pin hole. As long as the piston was still in the bore it would seem that it would all still be contained in the piston to some extent. If the rod simply snapped, why would the pin hole be pulled out like that?

Edit: Again, I should have checked up before hitting submit. Back and forth here at work...lol. Takes 20 minutes to make a simple post
newmann
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newmann 10/24/2018 8:04am
10/24/2018 8:04am
kb228 wrote:
The mechanic should have found other worn parts and assembled it correctly so it doesnt blow up. Thats his job.
newmann wrote:
OP already stated that no bolt was dropped into the engine during assembly. OP already stated the piston was replaced, supposedly with an OEM part. What...
OP already stated that no bolt was dropped into the engine during assembly.

OP already stated the piston was replaced, supposedly with an OEM part.

What other worn parts should the mechanic have found while freshening up a 25 hour top end on a 450? Should crankshaft assembly replacement be considered routine maintenance at 25 hours on a 450? That's where I would probably call bullshit and be looking for another builder...Wink

Until someone convinces me otherwise with information not already provided in this thread, I still see a massive piston failure.
kb228 wrote:
Kawasaki themselves say to check the crank every 15 hours. You should be checking the crank every time youre in there anyways. Replacement is unlikely but...
Kawasaki themselves say to check the crank every 15 hours. You should be checking the crank every time youre in there anyways. Replacement is unlikely but you never know. If we use that logic, pistons shouldnt be breaking at first startup either. Realisticly the mechanic could have not used assembly lube on the cylinder walls and it bound up.
Like you said, pistons shouldn't break. That's why OP should have insisted the builder tear it down even if he had to pay. If the piston failed for no apparent reason and no fault of the builder he should have gone back to the parts supplier to see if there could be any help or assistance available if it is a known problem. Everyone is flying blind here at the moment.

There are always threads on so and so's junky aftermarket crank assemblies that fail in short order. At this point we don't even really know that this was an OEM replacement piston kit.

I had an IMS rod kit failure within 20 minutes of a crank rebuild and fresh top end on our 01 RM125. The upper rod /piston pin bearing as supplied in the kit was a shit design and shattered sending more than half the cage and bearings through the engine. Bit of a mess, and no help from IMS. What I learned from that was to go OEM whenever possible. IMS sourced all those rod kits from overseas, probably China. While I have used plenty of IMS kits without failure, I never trusted a bearing of theirs after that. Used to buy those kits by the dozen for vintage Elsinores.
DynoDan22
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DynoDan22 10/24/2018 10:30am
10/24/2018 10:30am
Newmann,

Here's a scenario that is plausible:

Circlip came out on the side of the piston with broken wristpin boss. The wristpin started walking out in that direction until it wasn't in contact with the other pin boss in the piston (pin boss still intact). Since the wristpin was then only connected by one pin boss in the piston, the piston cocked in the bore and the wristpin broke out of the remaining boss in the piston. Since the wristpin was only connected at one pin boss in the piston, the twisting load on the top of the rod (sideways) would be enough to snap the rod (rods aren't designed to take any twisting side load). Plausible and it would explain the short runtime after the rebuild.
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Tracktor
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Tracktor 10/24/2018 10:39am
10/24/2018 10:39am
DynoDan22 wrote:
Newmann, Here's a scenario that is plausible: Circlip came out on the side of the piston with broken wristpin boss. The wristpin started walking out in...
Newmann,

Here's a scenario that is plausible:

Circlip came out on the side of the piston with broken wristpin boss. The wristpin started walking out in that direction until it wasn't in contact with the other pin boss in the piston (pin boss still intact). Since the wristpin was then only connected by one pin boss in the piston, the piston cocked in the bore and the wristpin broke out of the remaining boss in the piston. Since the wristpin was only connected at one pin boss in the piston, the twisting load on the top of the rod (sideways) would be enough to snap the rod (rods aren't designed to take any twisting side load). Plausible and it would explain the short runtime after the rebuild.
I don't think there is enough room side to side for piston pin to migrate that much. It would hit cylinder wall. Plus, circlip would've probably killed motor by itself. Seen it happen before.........

And to someone saying not using assembly lube on a cylinder would cause this? Uh, no. Just no...............
DynoDan22
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DynoDan22 10/24/2018 11:09am
10/24/2018 11:09am
There is enough room for the wristpin to migrate to one side and lose engagement with the other pin boss. look at the inside of the remaining pin boss and you can see the scuff marks where the edge of the wristpin was rubbing the inside of the boss.
RGaede
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RGaede 10/24/2018 6:06pm
10/24/2018 6:06pm
It's possible that a circlip was not installed allowing the pin to walk as well. I've seen people get in such a hurry they've gotten bikes back together only to pull them back apart after seeing the clips on the bench.
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Hcallz5
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Hcallz5 10/24/2018 8:40pm
10/24/2018 8:40pm
What are the details in terms of when the motor locked up? Were you going off a jump? Were you on a long hillclimb?


I wanna know why there's a bolt between the crank and the bottom of the piston. There's no bolts anywhere near that area.
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Jbarros23
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Jbarros23 10/24/2018 9:12pm
10/24/2018 9:12pm
Hcallz5 wrote:
What are the details in terms of when the motor locked up? Were you going off a jump? Were you on a long hillclimb? I wanna...
What are the details in terms of when the motor locked up? Were you going off a jump? Were you on a long hillclimb?


I wanna know why there's a bolt between the crank and the bottom of the piston. There's no bolts anywhere near that area.
My son was racing at hangtown, going up the top hill double. Died mid air
project racer 10/24/2018 10:07pm
10/24/2018 10:07pm
Looking at the chunk of cylinder skirt broken off, it looks like the pin migrated out far enough to catch the bottom of the skirt, breaking the piston /rod.
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newmann
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newmann 10/25/2018 5:59am
10/25/2018 5:59am Edited Date/Time 10/25/2018 6:00am
Hcallz5 wrote:
What are the details in terms of when the motor locked up? Were you going off a jump? Were you on a long hillclimb? I wanna...
What are the details in terms of when the motor locked up? Were you going off a jump? Were you on a long hillclimb?


I wanna know why there's a bolt between the crank and the bottom of the piston. There's no bolts anywhere near that area.
Three pages of photos, schematics and explanations later and there still isn't a bolt anywhere near that area. Ha, pure comedy.Laughing

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newmann
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newmann 10/25/2018 6:03am
10/25/2018 6:03am
And we already threw the poor mechanic under the bus!

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Jbarros23
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Jbarros23 10/25/2018 6:11am
10/25/2018 6:11am
Hcallz5 wrote:
What are the details in terms of when the motor locked up? Were you going off a jump? Were you on a long hillclimb? I wanna...
What are the details in terms of when the motor locked up? Were you going off a jump? Were you on a long hillclimb?


I wanna know why there's a bolt between the crank and the bottom of the piston. There's no bolts anywhere near that area.
newmann wrote:
Three pages of photos, schematics and explanations later and there still isn't a bolt anywhere near that area. Ha, pure comedy.Laughing


Here's the bolt
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slipdog
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slipdog 10/25/2018 6:43am
10/25/2018 6:43am
project racer wrote:
Looking at the chunk of cylinder skirt broken off, it looks like the pin migrated out far enough to catch the bottom of the skirt, breaking...
Looking at the chunk of cylinder skirt broken off, it looks like the pin migrated out far enough to catch the bottom of the skirt, breaking the piston /rod.
It's tough to diagnose a failure from pictures, but that break looks too offset from the centerline to be from the pin. I would like to see if the circlip was found in the corpse as well as see pictured of the cylinder bore. If the circlip came out or was left out there should be obvious markings in the cylinder where the pin backed out.

newmann
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newmann 10/25/2018 7:53am
10/25/2018 7:53am
Hcallz5 wrote:
What are the details in terms of when the motor locked up? Were you going off a jump? Were you on a long hillclimb? I wanna...
What are the details in terms of when the motor locked up? Were you going off a jump? Were you on a long hillclimb?


I wanna know why there's a bolt between the crank and the bottom of the piston. There's no bolts anywhere near that area.
newmann wrote:
Three pages of photos, schematics and explanations later and there still isn't a bolt anywhere near that area. Ha, pure comedy.Laughing

Jbarros23 wrote:
[img]https://p.vitalmx.com/photos/forums/2018/10/25/298325/s1200_Screenshot_20181025_060949_eBay.jpg[/img] Here's the bolt

Here's the bolt
Oh, I know where the bolt is. Just having a hard time wondering why 70% of the others can't see it. I would like to see some more pics of the piston, the inside of the cylinder and the underside of the head. When you pulled the piston out, was the pin and upper part of the rod still in the piston or out loose in the engine?

You and the engine builder still on speaking terms? Has he offered any input or has he still not seen the damage?
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newmann
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newmann 10/25/2018 8:03am
10/25/2018 8:03am
project racer wrote:
Looking at the chunk of cylinder skirt broken off, it looks like the pin migrated out far enough to catch the bottom of the skirt, breaking...
Looking at the chunk of cylinder skirt broken off, it looks like the pin migrated out far enough to catch the bottom of the skirt, breaking the piston /rod.
slipdog wrote:
It's tough to diagnose a failure from pictures, but that break looks too offset from the centerline to be from the pin. I would like to...
It's tough to diagnose a failure from pictures, but that break looks too offset from the centerline to be from the pin. I would like to see if the circlip was found in the corpse as well as see pictured of the cylinder bore. If the circlip came out or was left out there should be obvious markings in the cylinder where the pin backed out.

^^^^

The cylinder skirt broke off at the front from looking at the photo. It looks pretty much unsupported where it rests down inside of the engine cases. My guess would be the chunk of piston that broke off slammed through it. It would have started out on that side of the engine when it snapped off.
NoMuff2Tuff
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NoMuff2Tuff 10/25/2018 8:11am
10/25/2018 8:11am Edited Date/Time 10/25/2018 8:14am
In reality no one may never know exactly what caused it to blow up. You have a bike with 25 hours that was running fine then a new piston was installed and 20 minutes later BOOM. Owner said nothing was left inside and if no wrist pin scaring on the cylinder wall from the pin backing out, then I would believe the new stock cast piston straight up failed. I can't see the rod just snapping when it was fine during the first 25 hours then all of a sudden snap 20 minutes later after the top end was rebuilt. With 55 HP and turning 10,000 rpm I know anything can happen but the timing of when it happen leaves me to believe the new piston failed. Maybe it was a bad cast piston and had defects you couldn't see.
kb228
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kb228 10/25/2018 8:25am
10/25/2018 8:25am
NoMuff2Tuff wrote:
In reality no one may never know exactly what caused it to blow up. You have a bike with 25 hours that was running fine then...
In reality no one may never know exactly what caused it to blow up. You have a bike with 25 hours that was running fine then a new piston was installed and 20 minutes later BOOM. Owner said nothing was left inside and if no wrist pin scaring on the cylinder wall from the pin backing out, then I would believe the new stock cast piston straight up failed. I can't see the rod just snapping when it was fine during the first 25 hours then all of a sudden snap 20 minutes later after the top end was rebuilt. With 55 HP and turning 10,000 rpm I know anything can happen but the timing of when it happen leaves me to believe the new piston failed. Maybe it was a bad cast piston and had defects you couldn't see.
Buy forged kids
DynoDan22
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DynoDan22 10/25/2018 8:28am
10/25/2018 8:28am
jeffro503 wrote:
This pic......how? [img]https://p.vitalmx.com/photos/forums/2018/10/21/297690/s1200_20181013_114833.jpg[/img]

This pic......how?


kb228 wrote:
The rod cracked off the boss surrounding the bolt causing it to be loose, then caught or wedged against the bolt to rip it out.
It's interesting that the rod broke at an angle on the small end as shown in the pic above which supports uneven side loading. It does look like the pin walked out to me and left the piston/rod in single shear. If the pin did walk out and was only engaged in the one piston boss, the bending load would fatigue the piston boss and rod end until the piston failed at the boss.
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NoMuff2Tuff
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NoMuff2Tuff 10/25/2018 8:56am
10/25/2018 8:56am
jeffro503 wrote:
This pic......how? [img]https://p.vitalmx.com/photos/forums/2018/10/21/297690/s1200_20181013_114833.jpg[/img]

This pic......how?


kb228 wrote:
The rod cracked off the boss surrounding the bolt causing it to be loose, then caught or wedged against the bolt to rip it out.
DynoDan22 wrote:
It's interesting that the rod broke at an angle on the small end as shown in the pic above which supports uneven side loading. It does...
It's interesting that the rod broke at an angle on the small end as shown in the pic above which supports uneven side loading. It does look like the pin walked out to me and left the piston/rod in single shear. If the pin did walk out and was only engaged in the one piston boss, the bending load would fatigue the piston boss and rod end until the piston failed at the boss.
If the pin did move, I would think the cylinder wall would be scarred. He needs to post a pic of the inner cylinder wall.
kb228
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kb228 10/25/2018 9:51am
10/25/2018 9:51am
kb228 wrote:
The rod cracked off the boss surrounding the bolt causing it to be loose, then caught or wedged against the bolt to rip it out.
DynoDan22 wrote:
It's interesting that the rod broke at an angle on the small end as shown in the pic above which supports uneven side loading. It does...
It's interesting that the rod broke at an angle on the small end as shown in the pic above which supports uneven side loading. It does look like the pin walked out to me and left the piston/rod in single shear. If the pin did walk out and was only engaged in the one piston boss, the bending load would fatigue the piston boss and rod end until the piston failed at the boss.
NoMuff2Tuff wrote:
If the pin did move, I would think the cylinder wall would be scarred. He needs to post a pic of the inner cylinder wall.
The wall is screwed. The pic he posted shows a big ol gouge
newmann
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newmann 10/25/2018 11:17am
10/25/2018 11:17am
kb228 wrote:
The wall is screwed. The pic he posted shows a big ol gouge
X-Ray vision? I see a small nic or gouge at the rear lower area where the rod would have hit and a chunk broke off the front lower. I see no side shot of the bore. I also see only one pic of the underside of the piston.

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