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Robert 65

Montesa 248 oil from exhaust

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Hello

I was having oil coming out of the exhaust.

I've changed the crankshaft seals 

No improvement 

Petrol/oil ratio not the problem

Any thoughts

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57 minutes ago, Robert 65 said:

Hello

I was having oil coming out of the exhaust.

I've changed the crankshaft seals 

No improvement 

Petrol/oil ratio not the problem

Any thoughts

Perhaps the silencers are that clogged up with oil ?

Edited by rotors7

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Evening

Many thanks for your information.

How do I remove the obstruction?

Is it carbon the obstruction?

Once again thank you.

Stay safe and well.

 

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Take it for a long ride or burn out the excess oil with a blow torch

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The oil you see is probably condensed vapour/smoke from the combustion process. Modern two-stroke oils can be so good at resisting burning that they can cause what you are seeing. Once the sound absorbtion material in the exhaust is fully wet with this oil and it can't hold any more, it will start coming out wherever it can. It really doesn't do anything except make a mess so if you can manage the mess then you don't have to do anything. If you rode the bike hard enough the exhaust may get hot enough to stop the oil condensing inside the exhaust. Also if you ride it hard enough with oil already in there, it may clean it out to some degree. If you decide to clean out the exhaust by taking it off (it can be cleaned out a few ways when off the bike) but still continue to ride in the same manner, it will continue to fill up with oil. I've seen bikes with a drain line at the low point and when the bike is parked, they put a container under the drain line to catch what comes out.

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What ratio are you running, anything over 50:1 will exaggerate the problem. 

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I have had two strokes do this, remove exhaust, tip it out. It builds up over time, I used to find after riding my TY 250 on the road at higher speeds the oil in the system would get really hot and smoke like crazy even for a while after turning off the motor.

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20 hours ago, feetupfun said:

The oil you see is probably condensed vapour/smoke from the combustion process. Modern two-stroke oils can be so good at resisting burning that they can cause what you are seeing. Once the sound absorbtion material in the exhaust is fully wet with this oil and it can't hold any more, it will start coming out wherever it can. It really doesn't do anything except make a mess so if you can manage the mess then you don't have to do anything. If you rode the bike hard enough the exhaust may get hot enough to stop the oil condensing inside the exhaust. Also if you ride it hard enough with oil already in there, it may clean it out to some degree. If you decide to clean out the exhaust by taking it off (it can be cleaned out a few ways when off the bike) but still continue to ride in the same manner, it will continue to fill up with oil. I've seen bikes with a drain line at the low point and when the bike is parked, they put a container under the drain line to catch what comes out.

Morning

Many thanks for your reply.

Feel much better reading this.

It's been stood in garage for years 

Has mentioned I changed the crankshaft seals that were rock hard.

New oil,plug, points etc 

Started straight away.

I'm running 30 to 1

What oil should I add to the petrol,?

Best regards

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20 hours ago, b40rt said:

What ratio are you running, anything over 50:1 will exaggerate the problem. 

Running 25 to 1 

What oil should I add to the oil 

 

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20 hours ago, feetupfun said:

The oil you see is probably condensed vapour/smoke from the combustion process. Modern two-stroke oils can be so good at resisting burning that they can cause what you are seeing. Once the sound absorbtion material in the exhaust is fully wet with this oil and it can't hold any more, it will start coming out wherever it can. It really doesn't do anything except make a mess so if you can manage the mess then you don't have to do anything. If you rode the bike hard enough the exhaust may get hot enough to stop the oil condensing inside the exhaust. Also if you ride it hard enough with oil already in there, it may clean it out to some degree. If you decide to clean out the exhaust by taking it off (it can be cleaned out a few ways when off the bike) but still continue to ride in the same manner, it will continue to fill up with oil. I've seen bikes with a drain line at the low point and when the bike is parked, they put a container under the drain line to catch what comes out.

Thank you for your reply

Never had this running before

Owned for years

Feel happier now

Thank you

 

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8 minutes ago, Robert 65 said:

Running 25 to 1 

What oil should I add to the oil 

 

What oil should I add to the petrol

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20 hours ago, b40rt said:

What ratio are you running, anything over 50:1 will exaggerate the problem. 

25 to 1 what oil should I add to the petrol

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1 hour ago, Robert 65 said:

25 to 1 what oil should I add to the petrol

I'd run it at 50:1, 100ml to 5 litres of petrol using a quality semi synthetic 2 stroke oil.

Even at this reduced rates it will smoke and build up in the crankcase and exhaust. As said above, it needs decent run to get some heat into it to burn off excess, or cleaned out and repacked if this isn't possible.

Edited by b40rt
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Morning

Thank you for your reply.

Will try it later on today.

Much appreciated

Rob

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