hi

My father pulled his head off his motor today and the tops of 3 pistons were fairly clean and piston 4 was full black can somebody please explain why?

It was re-ringed not that long ago however there was a problem with getting one of the rings in and it bent so had to be replaced with another one we had - could this replacement ring be haddit and causing oil to the to come up causing smoke and hence the piston to be black?

Thanks Brenton

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Very possibly. There could be a variety of causes - burning oil would be number one suspect, either through the rings or the valve guides.

Either that or the other three are running too much fuel.

dodgy spark plug

too hard to tell with the head off, put new guides in the head if they aren't already, new plugs, and how it runs with the lead off that one, check the compression etc. etc.

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