Doctor, could you give me a diagnosis please?

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Time Warp said:
Did 850's come with copper head gaskets or maybe the head has been off before but looks like a typical hardly used, been sitting might have worn guides (or the seals died of old age) Brit bike top end to me.
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Yes, it had been sitting for a while so that could be right. Not sure if copper or composite gaskets were originally fitted tbh.
 
mean gene said:
Was the bike running or did you just buy it? Not an expert BUT I have never seen a piston that clean with 6,000 miles. I do agree with valve guide or seals on dirty cylinder. Good luck
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Yes, it was running. I didn't get far on it though as it starting spluttering ( and cut out a couple of times) as though starved of fuel.

I made it home and checked the fuel pipes & carbs. They were gooed up with old fuel jelly confirming the bike had been sat for a while.
 
Bonzo said:
Not sure if copper or composite gaskets were originally fitted tbh.
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Doctor, could you give me a diagnosis please?


06.5051.
andover-norton.co.uk

Andover Norton - GASKET - CYLINDER HEAD 850 (EYELET) - 06.5051

GASKET - CYLINDER HEAD 850 (EYELET)
andover-norton.co.uk

Same in the Mk2/2A supplement.
 
Bonzo said:
It's an RH10 head.
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Bonzo,
Well you got the good head as RH4's had a bad rap for cracks in the intake tunnel. That's why Fullauto heads were developed.
Normally the 850 should have a flame ring gasket as noted above but I bought an 850 (Not new) which had a copper gasket. YMMV. Is the oil coming from the weep of the gasket or a blown guide seal?
Yours to find out.
Be methodical.
Cheers,
Tom
 
CanukNortonNut said:
Bonzo,
Well you got the good head as RH4's had a bad rap for cracks in the intake tunnel. That's why Fullauto heads were developed.
Normally the 850 should have a flame ring gasket as noted above but I bought an 850 (Not new) which had a copper gasket. YMMV. Is the oil coming from the weep of the gasket or a blown guide seal?
Yours to find out.
Be methodical.
Cheers,
Tom
Click to expand...
It's pointing towards the guide seal but I'll post my findings as soon as. (I have a rocker spindle extractor - but need to buy a VS compressor)

Appreciate your words Tom, cheers.
 
Bonzo said:
(I have a rocker spindle extractor - but need to buy a VS compressor)
Click to expand...

The cheap compressors off the likes of eBay work like a dream (As long as you tap the end with a soft hammer to unseat the collets with some tension wound on)

Doctor, could you give me a diagnosis please?
 
Bonzo said:
I cant see past this one from RGM to be honest..
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Its a free world. :D

$60 + 20% VAT ? or $19.95 (IIRC)

A tool that might see a few minutes actual use once in a blue moon.
$4000 spent on the cylinder head, $2000 on the wheels, $20 for the spring compressor (bought years ago)
 
Bonzo said:
It's pointing towards the guide seal but I'll post my findings as soon as. (I have a rocker spindle extractor - but need to buy a VS compressor)

Appreciate your words Tom, cheers.
Click to expand...
You won't need the rocker spindle extractor to change the seal
I'm guessing you are going to strip the head for the exhaust thread work?
 
Yep, fair point. It's true.

I hope I'd rarely have to use it.

In the UK it works out at about £40 delivered
 
baz said:
You won't need the rocker spindle extractor to change the seal
I'm guessing you are going to strip the head for the exhaust thread work?
Click to expand...
Yes mate.

I'd rather not have to but there'll be plenty of swarf I'd imagine.
 
Spindles can be extracted easily without the special tool or a slide hammer. I did it several times with a suitable length/thread pitch bolt and a box wrench used for spark plugs as a hollow tube spacer. Some thick washers and a nut to wind down against the box wrench, bolt threaded into spindle end, pre-heated the head alu around spindle to expand things a bit, eases out nicely.
Re-fitting is just more heating and gentle tapping in with a rubber mallet. Hardest part is getting the thackery and thrust washers all lined up.
 
comnoz said:
Am I seeing things backward? It looks to me like the LH cylinder has an oiling problem with it's washed clean piston and chamber.
The carbon on the RH piston looks normal -a bit rich. Jim
Click to expand...
And...can people please stop pushing the hone and new rings (at less than 7000 miles) until the real status is identified.

The bore is capable of 100,000 miles, why mess with it if it isn't a problem!

Disassemble and inspect head....check all valve parameters and seals....do required repairs including threads.

Disassemble and measure pistons and rings....

Might as well take your time and only do what you need on a bike that is just about run in after 47 odd years!
 
SteveA said:
And...can people please stop pushing the hone and new rings (at less than 7000 miles) until the real status is identified.

The bore is capable of 100,000 miles, why mess with it if it isn't a problem!

Disassemble and inspect head....check all valve parameters and seals....do required repairs including threads.

Disassemble and measure pistons and rings....

Might as well take your time and only do what you need on a bike that is just about run in after 47 odd years!
Click to expand...
Great conversation but I am confused the piston tops in the first post seem to have circles on them. Are they valve clearance cuts or carbon shades or ? To me the rest of the photos don't look the same as the other (first) pic, the burn marks, oil, soot all except the gasket look different but as I said I am confused .Could you please enlighten me. Cheers Ian
 
Hi Ian,

I had to go back and look a couple of times to see what you were referring to - but I think I get you now.

The first pic does appear to have an arc pattern on top of the pistons.

I shone a torch in there and that is a reflection. The other shots (valves) I didn't need a torch.
 
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