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Hi
I owe Duke 390. Recently I am observing that engine RPM oscillates while running in idle and comes back to normal. Some times check engine light glows and engine stalls. Can anyone guess what must be wrong. Service Stations are not able to detect the problem. I am in Pune India, and have visited authorised service stations.

Regards
Rajesh
 

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Hi
I owe Duke 390. Recently I am observing that engine RPM oscillates while running in idle and comes back to normal. Some times check engine light glows and engine stalls. Can anyone guess what must be wrong. Service Stations are not able to detect the problem. I am in Pune India, and have visited authorised service stations.

Regards
Rajesh
Did you solve the problem?
 

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It would seem that this is related to the fact that stock KTM Duke 390's are running extremely lean to respect emissions regulations . Add to that poor oxygenated air in hot weather areas ... cheapest solution is flash the Akra map onto the ECU or a piggy back ECU .
 

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It would seem that this is related to the fact that stock KTM Duke 390's are running extremely lean to respect emissions regulations . Add to that poor oxygenated air in hot weather areas ... cheapest solution is flash the Akra map onto the ECU or a piggy back ECU .
I have powertronics installed. It was running good till now, but now it wont idle.
 

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In that case you should start with disconnection the battery for 10 min and reconnect . Check voltage output .
 

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Here in Brazil we have several problems with body fuel injection with dirt and gives the same behavior. Take a look.
Luis
 

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In that case you should start with disconnection the battery for 10 min and reconnect . Check voltage output .
Here in Brazil we have several problems with body fuel injection with dirt and gives the same behavior. Take a look.
Luis
Tried everything. Swapped throttle body, fuel tank and ecu from my buddy's duke still the same problem.
I think i have a blown head gasket. I see bubbles in radiator. Could leaking head gasket cause this?
 

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High engine temp ?
Yes i got high coolant warning. But it was because there was almost no coolant in the radiator. Coolant in reservoir did not drop though. I think this was because the gases from the cylinder pressurized the cooling system, not letting coolant from reservior to fill the radiator.

Already ordered head gasket and it is on its way.

Could i have some electrical issue or it could be the blown head gasket.
 

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It seems heat and head gaskets aren't an uncommon issue for 390 :(
This is something I'm nervous of having had some major issues on other bikes and cars in the past - but I'm in a cold climate so hopefully that will be in my favour.

A failed gasket will push the coolant out of the system as you described, but it is most likely to be heat that caused the gasket to fail in the first place.
Poor quality fuel and lean running make for a hot engine, and it seems this motor is designed to be lean and therefore hot to meet emissions standards and protect the cat from unburnt fuel.

KTM state "The thermostat opens at 88° C and is fully open at 96° C. The waterpump pumps the coolant through the cylinder, cylinder head, the radiator and the thermostat. The pressure in the cooling system (max 1.4 bar) is regulated by a valve in the radiator cap.
The fan switches on at 96° C and off at 90° C."

So it seems that the fan and thermostat are working closely together to keep the jacket temperature 88-96.

If it were mine I'd be looking at ways to eliminate the thermostat after the repair and see how it behaves. It might run too cool, in which case maybe it really needs to be there, but I suspect in a hot climate it would be fine without it.
I'd also get the mating faces of the cylinder and head checked and machined flat if needed - IMO just installing the gasket without doing this is likely to result in a repeat failure, and you will already have done most of the work to strip it down this far..

Basic things to check are:
Thermostat - maybe doesn't open fully or too late?
Fan switch - even if it appears to work, what temp does it come on?

Other than that, things like timing, mixture etc. are not going to be simple to check - but if you have a modified ECU etc. then removing the mods and running standard would be a good starting point.

Keep us updated and good luck...
 

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Yes Sidd, a blown head gasket can (and almost always is the) cause air bubbles in the coolant system.
 

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Yes i got high coolant warning. But it was because there was almost no coolant in the radiator. Coolant in reservoir did not drop though. I think this was because the gases from the cylinder pressurized the cooling system, not letting coolant from reservior to fill the radiator.

Already ordered head gasket and it is on its way.

Could i have some electrical issue or it could be the blown head gasket.
Possibly because of the blown gasket the ECU gets a wrong reading from the temperature gauge and could adjust the fuelling ( choke ) resulting in the rev surges and cut out's . my 2c
 
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