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Author Topic: Seized KTM 380exc: How to fix?  (Read 10937 times)

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Offline 2STROKEREVOLUTION

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Re: Seized KTM 380exc: How to fix?
« Reply #15 on: February 08, 2011, 01:55:23 PM »
Running extra oil? how much extra, extra oil could affect your jetting from what I've heard

Normally I run 60:1 fully synthetic. For this break in I was running 40:1. KTM recommends 40:1 to 60:1 for this bike.

Offline 2STROKEREVOLUTION

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Re: Seized KTM 380exc: How to fix?
« Reply #16 on: February 08, 2011, 02:00:02 PM »
I'll buy it off you or get the cylinder replated for you.Sleeves are bad news.

What is wrong with a sleeve?

My XR250 and YZ125 have steel sleeves and have no problems. High horsepower and high reliability car engines use steel sleeves.

The only downside I know of is a few ounces extra weight and slightly worse cooling. Both unnoticeable.

Offline TMKIWI

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Re: Seized KTM 380exc: How to fix?
« Reply #17 on: February 08, 2011, 03:21:13 PM »
What is wrong with a sleeve?


Most people on here will tell you why.
Chief among the problems is cooling. Instead of a nice thin wall for heat to travel through you now have a large heat sink.
Yes they do work and people do use them as a cheap option instead of replating.
If you are going to work your bike hard get it replated.

Hope you get to the bottom of the problem so it doesn't happen again.
If you don't fall off you are not going hard enough

Offline eprovenzano

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Re: Seized KTM 380exc: How to fix?
« Reply #18 on: February 08, 2011, 04:38:03 PM »
check that waterpump, the radiators, everything cooling system related, then check the crank, might be a bent rod..

Still don't see how it can be cooling issues when it was not running hot. It was perfect.

I will check the rod.

On my buddies bike the rod was bent.  It was difficult to see, but once we figured it out, the siezures made sense.
Eric Provenzano
2019 KTM 300 XCW TPI
2000 KTM 300 EXC (Son's)
2001 KTM 380 EXC
Sold 1991 KDX 200... fun play bike
Sold 1999 KX250
Sold 1999 YZ125 (son's)
Sold 2001 Yamaha TTL 125 (son's 1st bike)
Sold but never forgotten 1974 Honda Elsinore CR250M
Sold 1974 Honda Elsinore CR125

Offline 2T Institute

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Re: Seized KTM 380exc: How to fix?
« Reply #19 on: February 08, 2011, 11:36:33 PM »
I'll buy it off you or get the cylinder replated for you.Sleeves are bad news.

What is wrong with a sleeve?

My XR250 and YZ125 have steel sleeves and have no problems. High horsepower and high reliability car engines use steel sleeves.

The only downside I know of is a few ounces extra weight and slightly worse cooling. Both unnoticeable.

XR250's should never be referenced as any sort of a performance yardstick, plus they are infact air cooled. Yes cars have wet liners but they are normaly surrounded by many many litres of water.

Yes heat is the issue they cylinder is not designed to cope with the heat retention of the sleeve(the interface of the sleeve and cylinder is a thermal barrier) causes the engine to ping uncontrolably when hot. A RGV with sleeves I know locks solid if it's ridden in band for longer than 5 mins. When it cools down it goes fine.
Plating is actualy cheaper than a sleeve.
Want any more ?

Offline evo550

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Re: Seized KTM 380exc: How to fix?
« Reply #20 on: February 09, 2011, 04:07:56 AM »
I'll buy it off you or get the cylinder replated for you.Sleeves are bad news.

What is wrong with a sleeve?

My XR250 and YZ125 have steel sleeves and have no problems. High horsepower and high reliability car engines use steel sleeves.

The only downside I know of is a few ounces extra weight and slightly worse cooling. Both unnoticeable.


Want any more ?
What about powervalve/piston clearance issues, if steel cylinder is rebored?
Want any more?

Offline ford832

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Re: Seized KTM 380exc: How to fix?
« Reply #21 on: February 09, 2011, 04:38:18 AM »
I'd do either.Oddly enough,IC engines went a long time without a plated cylinder.
Plating is probably superior for the above mentioned reasons but the advantages are marginal in the real world.
On the upside,seize a piston on a plated cylinder and it's done,do it on a sleeve and typically a quick hone and you're off to the races.
I've used sleeves with no issues whatever.Given the choice,I'd probably get it plated BUT,if it's cracked anywhere,I'd probably put in a sleeve rather than get it welded-that seems to be 50/50 whether it's going to crack again or not-and sometimes cracks already there aren't detectable-until you ride it after your rebuild.
I'd rather a full bottle in front of me than a full frontal lobotomy.

Offline MyckMcClung

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Re: Seized KTM 380exc: How to fix?
« Reply #22 on: February 09, 2011, 05:30:49 AM »
60:1 !!!???? dude you might as well be running straight gas. ALWAYS break it in at 32:1!!!! Personally I run 12oz 24:1 then pour in 32:1 and run 3 gallons of that, full tank on my bike. IF it's blowing heavy spooge after that, I'll drop it to 40:1. 50:1 is the lowest I'll go, and that is after the motor is well broken in and there's black spooge pouring out of every available crevice that spooge can run from.
60;1 even with these new synthetics is just asking for trouble.
If a pair of 2" brass balls isn't working, I doubt that the 3" model will make much difference.

Offline MyckMcClung

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Re: Seized KTM 380exc: How to fix?
« Reply #23 on: February 09, 2011, 05:35:48 AM »
I have never had to perform a topend job before 50 hours with this method.
 at 50 hours I clean the head dome, powervalve, and piston, and replace the rings and small end bearing.
100 hours sees a new piston,rings, and seb.
If a pair of 2" brass balls isn't working, I doubt that the 3" model will make much difference.

Offline 2T Institute

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Re: Seized KTM 380exc: How to fix?
« Reply #24 on: February 09, 2011, 06:14:15 AM »
I'd do either.Oddly enough,IC engines went a long time without a plated cylinder.
Plating is probably superior for the above mentioned reasons but the advantages are marginal in the real world.
On the upside,seize a piston on a plated cylinder and it's done,do it on a sleeve and typically a quick hone and you're off to the races.
I've used sleeves with no issues whatever.Given the choice,I'd probably get it plated BUT,if it's cracked anywhere,I'd probably put in a sleeve rather than get it welded-that seems to be 50/50 whether it's going to crack again or not-and sometimes cracks already there aren't detectable-until you ride it after your rebuild.

Myth 298. After seizing a plated cylinder the fix is easier than a liner. Hydrochloric acid on a cotton bud and the aluminium fizzles away. Wash with water a 10 min job.
If a replated cylinder cracks it is the welding that is not up to standard.

Offline Charles Owens

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Re: Seized KTM 380exc: How to fix?
« Reply #25 on: February 09, 2011, 06:52:23 AM »
60:1, like Myc said IS asking for failures.
Get your bottom end re-built, fresh top and 32:1.
After that you can have more fun riding not worrying about early failure anymore. :)

Offline TotalNZ

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Re: Seized KTM 380exc: How to fix?
« Reply #26 on: February 09, 2011, 08:49:27 AM »
60:1 !!!???? dude you might as well be running straight gas. ALWAYS break it in at 32:1!!!! Personally I run 12oz 24:1 then pour in 32:1 and run 3 gallons of that, full tank on my bike. IF it's blowing heavy spooge after that, I'll drop it to 40:1. 50:1 is the lowest I'll go, and that is after the motor is well broken in and there's black spooge pouring out of every available crevice that spooge can run from.
60;1 even with these new synthetics is just asking for trouble.
exhaust spooge is an air/fuel issue not an oil/fuel mixture problem

Offline ford832

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Re: Seized KTM 380exc: How to fix?
« Reply #27 on: February 09, 2011, 10:00:53 AM »
I'd do either.Oddly enough,IC engines went a long time without a plated cylinder.
Plating is probably superior for the above mentioned reasons but the advantages are marginal in the real world.
On the upside,seize a piston on a plated cylinder and it's done,do it on a sleeve and typically a quick hone and you're off to the races.
I've used sleeves with no issues whatever.Given the choice,I'd probably get it plated BUT,if it's cracked anywhere,I'd probably put in a sleeve rather than get it welded-that seems to be 50/50 whether it's going to crack again or not-and sometimes cracks already there aren't detectable-until you ride it after your rebuild.

Myth 298. After seizing a plated cylinder the fix is easier than a liner. Hydrochloric acid on a cotton bud and the aluminium fizzles away. Wash with water a 10 min job.
If a replated cylinder cracks it is the welding that is not up to standard.


Myth 299.Straight hydrochloric is way too harsh-Muriatic is what is commonly used.Even then,a little pick in the plating from the seize and it will eat in to that and under the plating-also be super careful in the port area.Just leave it on for a few seconds and rinse well.It's rare to seize a piston and not damage the cylinder unless you realized what was happening and shut it down before it locked up-despite what it looks like from gawking down in to it.Typically,it's days are numbered at this point.
Many rewelded cylinders crack at the base of the weld-typically they are not the easiest thing to access and any crack,welded or not,creates a stress riser.It's hard to blame the welder for that.
Many also crack elsewhere afterwards.Given the heat and stress when the seizure occurs it's not uncommon to create a hairline crack that isn't visible-even with a boroscope.

Myth 300. You know more than I do. :o ;)
I'd rather a full bottle in front of me than a full frontal lobotomy.

Offline Coop

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Re: Seized KTM 380exc: How to fix?
« Reply #28 on: February 09, 2011, 12:04:27 PM »
exhaust spooge is an air/fuel issue not an oil/fuel mixture problem

You beat me to it. If you are getting excessive spooge, fix your jetting, don't mess with the mix.
- Mike - Don't take life so seriously, nobody gets out alive.

Offline ford832

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Re: Seized KTM 380exc: How to fix?
« Reply #29 on: February 09, 2011, 12:32:39 PM »
That's true but at the same time,even a correctly jetted bike will spooge somewhat if one has a weak right wrist or rides in eastern type off road conditions.
I'd rather a full bottle in front of me than a full frontal lobotomy.