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Elias Smith

Burning oil fix?

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Hi not sure if this is in the right category so excuse me if it is, but...Before I changed the oil on my ktm 525 it showed no evidence of burning any oil. After adjusting the valves and putting in fresh good quality 10w40 it blows blue smoke after a rev and generally smoke more after idling for a bit. Would changing the oil to the recommended 10w50 solve the issue? Valves are on factory spec. Smoke isn't thick and its not too much to be a big problem...

Any help will be greatly appreciated.

Thanks!

Edited by Elias Smith

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1 hour ago, Elias Smith said:

Hi not sure if this is in the right category so excuse me if it is, but...Before I changed the oil on my ktm 525 it showed no evidence of burning any oil. After adjusting the valves and putting in fresh good quality 10w40 it blows blue smoke after a rev and generally smoke more after idling for a bit. Would changing the oil to the recommended 10w50 solve the issue? Valves are on factory spec. Smoke isn't thick and its not too much to be a big problem...

Any help will be greatly appreciated.

Thanks!

Overfilled? Bad valve seal? Time for a new top end? Those are the things I would investigate in order

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Overfilling does not cause burning in most cases.

The most common oil burning issue on the RFS head is worn out valve guide seals.

You say the oil burning was noticed after a valve clearance check.

I think that is a coincidence.

It's all part of normal maintenence.

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On 6/10/2021 at 3:26 AM, KRAYNIAL said:

Overfilling does not cause burning in most cases.

The most common oil burning issue on the RFS head is worn out valve guide seals.

You say the oil burning was noticed after a valve clearance check.

I think that is a coincidence.

It's all part of normal maintenence.

Okay would going from 10w40 to 10w50 help? if not i'll be replacing the valve guide seals.

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Cheap oil might contribute.  One of my 4-stroke outboard motors (only 50 hours on it so practically new) will smoke as you describe, especially after a hard run, when I use conventional oil.  I swapped it to Maxima synthetic bike oil and zero smoke.  Your valve stem guides and seals may very well be worn, but if you're using low grade oil now then I would swap for some name brand 10-50 bike oil and see what happens.  Even if your guides are worn, it's not a crisis emergency so there's no harm in running it another oil change or two to see what happens.  

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9 hours ago, sirthumpalot said:

Cheap oil might contribute.  One of my 4-stroke outboard motors (only 50 hours on it so practically new) will smoke as you describe, especially after a hard run, when I use conventional oil.  I swapped it to Maxima synthetic bike oil and zero smoke.  Your valve stem guides and seals may very well be worn, but if you're using low grade oil now then I would swap for some name brand 10-50 bike oil and see what happens.  Even if your guides are worn, it's not a crisis emergency so there's no harm in running it another oil change or two to see what happens.  

I'm using a decent oil brand but i'll swap it out for some motul after a ride. Either way as you said its not a big deal....

1 hour ago, Hubert Carpet said:

Does the engine breather feed back into the air box so any oil blown out by overfilling gets burned?

The breather hose is connected to the carb just before the airbox...I doubt the oil travels there as half of the hose is routed vertically. But it is a possibility... 

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Even a healthy motor, if you work it hard some oil mist is going to come out of the breather.  The spinning parts will whip some oil into a mist and the blowby will carry it right out the breather.  A worn motor will do this a lot more than a fresh motor, but it's going to happen on all motors to some degree.  If it's over filled by a good bit then it is possible that more might come out the breather.  If the breather goes into your airbox or carburetor area and you flip upside down, expect a lot of smoke... don't ask me how I know about that one.  😉   

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2 minutes ago, sirthumpalot said:

Even a healthy motor, if you work it hard some oil mist is going to come out of the breather.  The spinning parts will whip some oil into a mist and the blowby will carry it right out the breather.  A worn motor will do this a lot more than a fresh motor, but it's going to happen on all motors to some degree.  If it's over filled by a good bit then it is possible that more might come out the breather.  If the breather goes into your airbox or carburetor area and you flip upside down, expect a lot of smoke... don't ask me how I know about that one.  😉   

Thanks for the helpful info!! I'll certainly make sure I don't do either 😆

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Pull the breather hose and see if it's wet with oil. I would expect that you'd get a fine mist or vapour blown by crankcase pressure so vertical pipe runs would be no obstacle.

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