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Trashed Bores....
r1_pete - 2/5/16 at 02:36 PM

Without dropping a handful of scrap down the spark plug hole It always mystifies me how bores could get so badly damaged.

The rings were intact, but about half the width of new ones, and the ring gap was about 5mm, but no appreciable lip at the top of the bores.

Compression was well down too - no $hit Sherlock!!

I've got another engine which I've stripped to freshen up with new bearings and rings, the aluminium silica bores seem really harsh on rings, these were worn to half their width too!!

Scrap block1
Scrap block1

Scrap block 2
Scrap block 2

Scrap block 3
Scrap block 3

David Jenkins - 2/5/16 at 02:42 PM

I wonder if your air filter is working as well as it should...

rusty nuts - 2/5/16 at 03:04 PM

Bore wash perhaps causing metal to metal contact due to running too rich?

britishtrident - 2/5/16 at 03:30 PM

That type of bore material is really sensitive to bore washing and small particles that get past the airfilter.
Even doing a compression testing without disconnecting the injectors has been blamed for damaging the bores.

steve m - 2/5/16 at 09:17 PM

I have never used an airfilter on my 7, and have never encounterd a score like that

steve

britishtrident - 3/5/16 at 05:12 AM

quote:
Originally posted by steve m
I have never used an airfilter on my 7, and have never encounterd a score like that

steve


Xflos don't have aluminium silica bores --- BMW ran into big trouble with this type of linerless bore some years back.

Running without an airfilter has been reffered to in the past by Andy Dawson as an "instant rebore kit".

rusty nuts - 3/5/16 at 06:03 PM

You only have to look at the state of the air filter on your tin top after a few thousand miles to see how much dust it catches . The dust can be highly abrasive which is what causes the wear