Doctor, could you give me a diagnosis please?

Bonzo said:
On the subject of +20 rebores, I notice RGM have new Hepolite piston sets (made in Taiwan?) for £83 or NOS for £190 (+ vat).

Would the originals be favorable for just over double the cost?
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The Taiwan pistons are the better piston. The same piston is also available under the Emgo and JCC brand.
 
One of the first pics appear to show rust pitting in one bore ,and from the low milage i would assume it stood for many years. Pitting will allow some oil burning but may decrease as the milage mounts up and the bore wears a few thou. Its a gamble but a hone and new rings may help.
 
By way of an update, I removed the valves last night..

Doctor, could you give me a diagnosis please?


And the first response was...

CanukNortonNut said:
R/H intake guide oil seal?
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Doctor, could you give me a diagnosis please?
 
..but CanukNortonNut was only half right.

The split seal was in the L/H inlet, this cylinder...

Doctor, could you give me a diagnosis please?
 
My lad came around yesterday with an internal micrometer...

Doctor, could you give me a diagnosis please?


...and the readings were...

Drive side - top of cylinder: 77.929, bottom: 77.030
Timing side - top: 77.025, bottom: 77.021 (mm)
 
Doctor, could you give me a diagnosis please?

Well I have a similar problem with excessive oil consumption. I tried to change out the two seals without taking the head off (via ludwigs quick fix), but reluctantly, I took the head off and found a different problem. This is a Statesman motorcycle. Over 100 K on the clock.
It has standard pistons. I have not put all the mileage on it, as I'm the 6th owner when it had 21k on the clock. But 80% was riden by me. I rebuilt the engine but started to note high oil consumption last year.

Doctor, could you give me a diagnosis please?

Here is what I found.
Doctor, could you give me a diagnosis please?

cylinders were not scored. I'm not sure how that happened. I'll need to check tolerances with my telescopic mike. No cylinders were washed out like your but Comstock has looked at more engines than I ever will. His good call.

Doctor, could you give me a diagnosis please?

I've got a couple of mods displayed to you sharp eyed snipers. See if you can pick them out. Think ludwig!
I got to pull this engine out and replace it with another 850 engine to get to the Nationals in NY Less than two weeks....
wish me luck.
Cheers,
Tom
 
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Charles Waggett said:
Rather that guess at the problem, do the right thing, Rebore to .020, new guides and valves too. Otherwise you will be doing the job 2 or 3 times.
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Bonzo said:
I take your point and you may be right, but I'll see how the bores measure up later before I change everything with so little mileage.
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If it ain't broke, you can't fix it.
 
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