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RC390 Overheated. Won't start.

rick

rick

New member
Joined
Aug 26, 2002
Location
Ojai
Moto(s)
Too many
I was putting along the highway around 6:30AM at the speed limit on a KTM RC390 with 6K miles and it died on me. It would rev to about 3K RPM for a second or so but, wouldn't hold. Once I got to the side of the road I tried to restart it and was unsuccessful. It would crank over but, not fire up.

After sitting a bit I tried the key again and saw that the temperature gauge was pinned. I let it sit for about half an hour until the temperature gauge dropped to about the middle of its range but, it still wouldn't catch. The oil looks good and the radiator overflow is at it's normal level.

After I was rescued and brought home, I put the bike on the charger and tried cranking it over some more. Again it would turn over but, wouldn't catch.

I pulled the spark plug which was wet and smelled of gas. I stuffed a paper towel into the spark plug hole and grounded the spark plug and turned it over again. Good spark and the paper towel shot out and hit the ceiling so, there's at least some compression. So, fuel, spark and compression is a check. What next?

I was gonna take it to my favorite local mechanic but, the dealer even if they're slower, more expensive and a PITA might be better if it's a medium to big warranty issue and they may be better equipped to read diagnostic codes. If it's a smaller warranty issue than I'd rather pay at my local shop and get back on the road faster. If it's not a warranty issue than I'd rather go to my local mechanic.

FWIW, this is the third time it's left me stranded in the 6 months I had it. The first was when the exhaust cam delaminated and took two months to fix. The other was a cracked radiator but, that was fixed the same day at a local radiator repair shop. Otherwise service has been as scheduled.
 
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Was the temp pinned while you were riding it and you just didn't see it? Or did the gauge just max out due to being shut off?
If it has spark and compression, the only thing left is fuel. The bike is FI right? Then a wet plug is a sign that something in the fuel system is wrong. Too much fuel pressure, injector sticking open...
btw- I'd check the compression again with a gauge. It doesn't take much to shoot a paper towel out.
 
Well that sux!

The basics:
Fuel does not seem to be the issue
Spark does not seem to be the issue
Compression does not seem to be the issue
Air - is there any obstruction in the air inlet or exhaust?
Timing: Ignition and mechanical timing

Since it overheated I would confirm the water pump is still pumping water
and
Since you had cam issues before, I would confirm ignition and cam timing is correct

Finally, since this is a relatively new bike that has been in the dealer due to warranty work (I presume the cam issue was warranty work), then I would not touch it and take it back to the dealer for them to do a presumed follow-up warranty repair.

If they troubleshoot it and determine it is not related to their previous repair, and it is something else, then, you can decide whether to fix it yourself or have them do it.
 
overheating can def cause issues thatd hinder starting. warped head, water in the cylinder, low compression, etc. id def get the dealer to do a compression or leakdown test.
 
Not a pretty picture but take it back to the dealer where all that warranty work was done.

There's a good chance they will have to fix it again gratis.
 
Thank you everyone!
1. I first noticed the temperature gauge reading several minutes after it shutdown on me on the highway. It may or may not have been reading high when the engine died originally. There was no indications that it had boiled over at any point.
2. I can throw a compression or a leakdown tester on it tonight. I'll have to wait until I get home to find what kind of numbers I'm looking for on the compression tester in the service manual.
3. I didn't check the airbox but, it seems to be pumping air based on a hand on the exhaust while it's cranking. The air filter was changed about 1.5K miles ago and there was no obvious damage to the outside of the airbox.
4. The water pump could be an issue. I've heard there may be an occasional issue with the rotor coming off the pump but, it was so horrible last time with the cam and draining the coolant seems like something they'd harp on to deny a warranty claim. I was planning to roll the dice and try a different dealer this time.
5. I'm hoping that the lack of oil-milkshake suggest that if it did overheat and if there was any heat damage that it didn't reach the head warping/gasket blowing phase at least.

So, I'll throw a compression tester on it and pull the valve cover to see if there's anything horrible going on under there tonight. I suppose if the cams look nasty then I have to go back to the same dealer as last time. Ugh.

EDIT: I'll have to look up checking the timing and injectors. :)
 
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Could it have contaminated fuel? If it was mine, I'd give it a shot of starting fluid and see if it lights. If it does, it is a fuel system issue. If not it could be an ignition or mechanical issue. Let us know what you find.
 
I did this cold becauseI didn't feel like burning my fingers but, the compression test only came up at about 105 PSI on my crusty old compression tester. However, the leakdown was perfect.

Pulling the valve cover now.
 
...cams were intact maybe a tad more wear than I'd like for almost new cams but, northing obvious wrong there. Come to think of it, I should have made sure that the gear weren't missing any teeth or anything. I also couldn't get the timing mark cover off and didn't feel like fighting with it too much. :(
 
It's certainly possible! The temperature gauge has reset back to zero FWIW.

Dealer opens at 9 so, I'll give 'em a call to schedule a service this morning. :(
 
Check out Motorcyclist magazine web site. Seems I recall reading of a bit of a head gasket problem on the RC when they get hot. It's in the Long Term Test section.


Dennis
 
So, I was putting it back together to take to the dealer Saturday morning and it fired right up. Figures.

It poured out a ton of white smoke out but, still no milkshake. It cleaned up after a few minutes and I ran it on the lift until it indicated about 4 bars on the heat gauge. Not hot enough for that fan to come on though. Took it to the dealer anyway.

I tried a new dealer this time and it was a wildly better experience than the last one! So nice! I gave him the whole run down of what happened and what I had checked. I also warned them that I probably nuked any error codes because I have to pull the battery to remove the fuel tank on this bike. He joked that I was making this diagnostic easy for themsaid that there's no reason for a bike this new to just die so, that if they do find anything wrong it'll almost certainly gonna be covered by warranty ...polar opposite of the other dealer!

About 2-1/2 hours later he called and said they found a leaky head gasket and that they'd keep digging. Sunday he called and said the head and jugs were warped too and they'd try to replace all of that under warranty. From the parts fiche it looks like the jugs, piston, rings, wrist pin, etc are all one part number and the entire head is one part number less the cams so, that probably means break-in again.

Still, progress!
 
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which dealer did you go to?

I'm in Lompoc and just blew my head gasket with 267 miles on the odometer... hoping that I can get SB Motorsports to warranty repair it and throw in a valve adjustment and maybe a slipper clutch while I'm at it! We shall see!
 
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