Stock 114 M8. Normal for an M8?
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Not uncommon. A little oil comes past the rings, a little comes from crankcase breathers, and the rest from combustion of fuel that comes from oil.
Thanks
For an M8...yes.
Quote from: rigidthumper on June 26, 2020, 08:58:59 AM
Not uncommon. A little oil comes past the rings, a little comes from crankcase breathers, and the rest from combustion of fuel that comes from oil.
Robin, do you think that the thick OEM head gasket is contributing to that?
Hard to say. I do believe wide quench areas lead to less efficient combustion, but I believe that a lot of the carbon found on tops of pistons is from less than perfect ring sealing.
I've not seen them with that amount of Carbon. What's the Mileage?
Quote from: Pirsch Fire Wagon on June 27, 2020, 06:38:32 AM
I've not seen them with that amount of Carbon. What's the Mileage?
8K miles. Bike does have more oil mist via the breathers than I ever saw in any TC. Both cylinders passed leak down test. So maybe these M8 bikes breather system doesn't work as well as the TC.
Re-route those breathers away from the intake.
Quote from: Hossamania on June 28, 2020, 06:11:01 AM
Re-route those breathers away from the intake.
Already done. But some carbon had already formed
Blow by as in combustion pressure leaking past the rings.
Quote from: RTMike on June 28, 2020, 06:32:17 AM
Blow by as in combustion pressure leaking past the rings.
That could be. Leak down test numbers were really good. But with engine running the pressures are higher. Those are some big pistons going up and down.
Take the air filter off and see if there is oil that has collected in the recess in the opening of the throttle body. It almost looks like the recess was intended to catch oil dripping from the breather hoses. About half the ones I've looked at have oil puddled there.
The oil on the piston above looks like carry over to me.
When the rings loose oil control, there will be a wet margin around the edge of the piston with a dryer looking center.
(https://i.imgur.com/Xbgm5WD.jpg)
Quote from: Thermodyne on June 29, 2020, 11:08:12 AM
Take the air filter off and see if there is oil that has collected in the recess in the opening of the throttle body. It almost looks like the recess was intended to catch oil dripping from the breather hoses. About half the ones I've looked at have oil puddled there.
The oil on the piston above looks like carry over to me.
When the rings loose oil control, there will be a wet margin around the edge of the piston with a dryer looking center.
(https://i.imgur.com/Xbgm5WD.jpg)
Good info. Thanks
Normal from what we've witnessed.