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jarmchairpilot Samba Member
Joined: March 04, 2013 Posts: 459 Location: GALWAY,IRELAND
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Posted: Sun Oct 04, 2020 2:17 pm Post subject: Engine rebuild question |
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I have my 1973 1200 crankcase split ready for a new set of jugs to install.
I only have a Vernier calipers to measure the bore of the case where the jugs sit.
It seems that 2 of the bores for cylinder 1 and 3 are at 90.4 mm and the 2 and 4 are at 90.3mm. I could be reading that wrong will check again tomorrow.
They are not out of round.
If the bore is on the max. limit of recommended tolerance does that mean the new p+b set will fit too loose, is there some gasket ring that I can use?
The engine is stock and had gone round the clock with just a top end rebuild 30k and 4 years ago. It was running ok but I can see the stock camshaft has slight brown lobes. Isn't that that to be expected, I can feel there is a little movement side to side where the connecting rods join the main crankshaft, will that disappear once I replace the big end bearings etc?
I hope so.
Thanks.
All the lifter bores look good and within spec.
Thanks. |
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Pruneman99 Samba Member
Joined: February 22, 2012 Posts: 5013 Location: Oceanside
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Posted: Sun Oct 04, 2020 2:23 pm Post subject: Re: Engine rebuild question |
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The cylinders seal on the face, not the skirt. If they are a bit loose, that's ok. |
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jarmchairpilot Samba Member
Joined: March 04, 2013 Posts: 459 Location: GALWAY,IRELAND
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Posted: Sun Oct 04, 2020 2:38 pm Post subject: Re: Engine rebuild question |
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That's a relief, a dual relief even haha,
a new crankcase or a machine shop oversize bore would be a few hundred bucks
more that I don't really want to spend to get about 35hp back on the road ! |
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Volks Wagen Samba Member
Joined: February 13, 2013 Posts: 2926 Location: Germany
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Posted: Mon Oct 05, 2020 2:10 pm Post subject: Re: Engine rebuild question |
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That's right what pruneman said. There used to be paper gaskets but they aren't a good idea. Some people use a little bit of sealant between the case and the cylinders - just a little. The bore at the case is OK. Check the height of the new cylinders against your old ones because sometimes they are different... Can affect the rocker arm geometry and the deck height. Do you have Tom Wilsons book? Good for rebuild info. _________________ 1973 1303 with AB-motor - sporadic
reconstruction as time permits, 1986 ex-Bundeswehr Doka - on the road again.
I'm definitely, probably, the worlds greatest lover.
Aithníonn ciaróg ciaróg eile. |
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