CS175 burning oil. Thoughts please everyone? - MVAgusta.net
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  • 2 Post By Mondello175
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post #1 of 6 (permalink) Old 11-15-2017, 01:54 PM Thread Starter
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CS175 burning oil. Thoughts please everyone?

I've now removed the cylinder head from my CS57 to investigate where the blue smoke is coming from. It got so bad that after a fairly long downhill I stopped at a roundabout and got overtaken by a blue cloud - embarrassing!
I've only had the bike a few months and it's the first look inside for me.
Anyway, I have my own thoughts on the problem but would like to know what others think, based on the photos.
So, thoughts please everyone?
And suggestions on how to resolve.
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Last edited by Mondello175; 11-15-2017 at 01:59 PM.
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post #2 of 6 (permalink) Old 11-15-2017, 02:01 PM
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Look at the exhaust valve guide, an excessive play between valve stem and valve guide will cause a "nice blue cloud of smoke".

You can look also the rings gap and if there is a step at the upper part of the bore (sign of a worn cylinder bore.
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Last edited by GTW36; 11-15-2017 at 02:03 PM.
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post #3 of 6 (permalink) Old 11-17-2017, 01:55 AM
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Running downhill with closed throttle creates a vacuum in your combustion chambers.

This will make the oil sucked into your combustion chaimber if:

a] Poor valve seals.
b] Worn or broken piston rings.
c] Piston rings stuck in their grooves.
d] Excessive wear on the cilinder.

You could try to put some fluid on top of the piston and see if it leaks away for a quick check. But the proper way would be to measure wear with a micrometer and compare it to the factory specification.
I think you have to pull the cilinders for a proper diagnose!

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post #4 of 6 (permalink) Old 11-19-2017, 04:14 PM Thread Starter
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and here's what I think

Thanks to GTW36 and RCEE for your suggestions.

I'm fairly sure the root cause is oil leakage down the valve guides but not because they are excessively worn - see my blog for more details and the solution I intend to implement.


Last edited by Mondello175; 11-19-2017 at 04:31 PM.
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post #5 of 6 (permalink) Old 12-06-2017, 07:22 PM
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Don't forget you can get reusable copper head gaskets from Copper Gaskets Unlimited. They are my pattern but Ronnie will sell you one. Make sure you get the "CSS" one with the larger stud holes. Hope it helps!

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post #6 of 6 (permalink) Old 12-07-2017, 06:00 AM
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Decel smoke.....valve guide. Your photos confirm. Combustion chamber and spark plug look nice and clean.

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