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13 450sxf overheat from no coolant

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Took my 450sxf for the first summer ride this year (she is a Timbersled conversion... hey, I was busy this spring!) to get her dialed in and had a little coolant trouble.  I was in really tight brush in an area that was recently logged and a stick poked through the side of the motor and knocked off my main coolant line up to the rads.  Literally all the coolant ran out before I could get down to the hose and reconnect it.  I got another few yards down the road and the fitting sprayed again... this time I noticed the tear the sharp stick created.  Long story short I had to ride the bike home with no coolant in it.  I would ride the bike lightly until the FI light turned on from the overheat, kill the bike, wait about 10 minutes, start up and do about another mile or so down the road until the light would come back on and I would kill the bike an repeat the process.  Had to do this about 5-6 times before I could walk the bike the rest of the way home.

 

I let the bike sit overnight and this morning when I went to it I noticed some oil on the ground from my crankcase breather tube I had rerouted out of the airbox.  It spat all over the back of the motor (rerouted for snowbiking reasons), but it didn't seem to be a ton of oil in total.  Some of the coolant had washed it off the block and it pooled in a few spots on my shop floor.  I've got a new hose on order but my question is what kind of damage may I have done to the bike?  It never ran low on power or felt funny... it was just really hot.  I figured since I was kind to it given the situation I may not have burned up the rings... but the oil spitting out of the crankcase has me a little concerned.  I'm going to do a compression test after I get the cooling system all back into place.

 

I've never seriously overheated a modern 4 stroke and I know how bad overheating a 2 stroke can be.  Thanks!

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This is a scenario where it could go one of like 25 ways.

Since you had no water, the only thing technically doing any cooling was the oil, which has no cooling system.

You could have done damage to the top end, or nothing at all.

While waiting for your parts i would start with,

Change oil/ filter, but take a good look at filter pleats for debris of any kind. May lead the way to a problem area.

Wouldnt hurt to see if valves out of adjustment. Sometimes running hot can effect that.

Once valvetrain adjusted,

If you can check compression, or do a leak down test.

Hopefully the fancy synthetic oil lived up to its rep and youre ok.

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Not to thread jack. But took my bike out this past weekend for its first ride on a 85 degree day. A couple times it spat just a bit of coolant on the pipe. Maybe just leveling off. But I was curious if the bike will shut itself off if it gets to hot? Sounds like from the previous poster the fi light will come on.

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I will pull the oil filter and check for debris when I change my oil.  I'll also do a compression test.  What PSI should I get out of this motor?

 

And a valve clearance check would be a good idea.  I noticed it's becoming a little less than instant start when warm on the button.  Used to be flawless... now sometimes I have to give it a tiny throttle blip.

Edited by Mefesto

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Mefesto, there technically is no spec on compression psi, mainly because of the auto decomp.

The best way to test with that said is a leak down.

Valve clearance is

Intake, .10-.15mm

Ex, .12-.17mm

Your starting issue might also have to do with the tps voltage. Ive noticed ktms are particular about it.

It seems these like .660 volts with throttle closed on a warm engine.

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I have read on KTMtalk about the TPS voltage issue.  It also seems to be related to the flame out issues the bike has when warm and starting off from idle.  Occasionally the bike will pop and die when you try to get going after a stop.  Very noticeable on the single track/backwoods riding.  How do I make this adjustment?

 

Appreciate the tips.  I will do a leak down and a valve check before my next ride.

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