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Author Topic: Seized KTM 380exc: How to fix?  (Read 5466 times)

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Offline Coop

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Re: Seized KTM 380exc: How to fix?
« Reply #30 on: February 09, 2011, 12:55:40 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.

Uhm, yeah, that's why I said "excessive" in my post... :P
- Mike - Don't take life so seriously, nobody gets out alive.

Offline 2T Institute

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Re: Seized KTM 380exc: How to fix?
« Reply #31 on: February 09, 2011, 01:39:05 PM »
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 ;)

The best way of stopping welding induced stress is the slow heat and cool cycle, the welder has control over that. Never had a straight seizure damage a cylinder, only when the piston disintergrates does the damage occur(usually from the rod flapping around). My replater has no problems welding anywhere in a cylinder, ports come back with the timing they went over there with. Cylinders still in use on engines that get a very hard life ie shifterkarts.
The use of a EGT gauge(or detonation counter) tells when seizure is close.

Offline riffraff

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Re: Seized KTM 380exc: How to fix?
« Reply #32 on: February 09, 2011, 07:13:41 PM »
So what should the EGT be and where would you measure it at? I have access to EGT probes and gauges.  What about CHT?
aaahhhhh yes, I remember the good old days

Offline MyckMcClung

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Re: Seized KTM 380exc: How to fix?
« Reply #33 on: February 09, 2011, 07:31:13 PM »
I don't believe I said excessive spooge,
what I meant was if there is an apearant amount of  spooge, it is then safer to lower the oil to fuel ratio.
southeastern woods
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4 year old bike on it's second spark plug(I only replaced it because I did a topend job, it was in perfect operating condition and now in my fanny pack as a back up to my back up)
very strong right wrist
If a pair of 2" brass balls isn't working, I doubt that the 3" model will make much difference.

Offline TMKIWI

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Re: Seized KTM 380exc: How to fix?
« Reply #34 on: February 09, 2011, 07:35:21 PM »
very strong right wrist

What do you do for exercise ?  ;) :P
If you don't fall off you are not going hard enough

Offline MyckMcClung

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Re: Seized KTM 380exc: How to fix?
« Reply #35 on: February 09, 2011, 07:41:58 PM »
Funny TMKIWI
"Aunt Flo" just came to visit for the week so looks like I'll be training this week.
If a pair of 2" brass balls isn't working, I doubt that the 3" model will make much difference.

Offline TMKIWI

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Re: Seized KTM 380exc: How to fix?
« Reply #36 on: February 09, 2011, 07:51:42 PM »
 ;D
If you don't fall off you are not going hard enough

Offline ford832

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Re: Seized KTM 380exc: How to fix?
« Reply #37 on: February 11, 2011, 08:18:33 AM »
very strong right wrist

What do you do for exercise ?  ;) :P


Bwhahahahahahahahahha.Good practice for married life if you're not already anyway :(
I'd rather a full bottle in front of me than a full frontal lobotomy.

Offline ford832

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Re: Seized KTM 380exc: How to fix?
« Reply #38 on: February 11, 2011, 08:24:10 AM »


The best way of stopping welding induced stress is the slow heat and cool cycle, the welder has control over that. Never had a straight seizure damage a cylinder, only when the piston disintergrates does the damage occur(usually from the rod flapping around). My replater has no problems welding anywhere in a cylinder, ports come back with the timing they went over there with. Cylinders still in use on engines that get a very hard life ie shifterkarts.
The use of a EGT gauge(or detonation counter) tells when seizure is close.

What?That's it? You're no fun :D
Maybe different quality of work in different place.
I've got EGT's on the snowmobile but probably not real practical for  a bike.
McClung-about 1.5" from the exhaust port is good.
I'd rather a full bottle in front of me than a full frontal lobotomy.