How to fit base gasket below cylinders without taking pistons out?

[Iffy650]

Hi,
I'm restoring a 1989 650. Cylinder head is off for recon. Cylinders bores look good and top of piston ok.
The gasket between the bottom of cylinder and top of block has been leaking and needs replaced but I don't want to lift the cylinders off the pistons as getting the pistons and piston rings back into the bores will be difficult. Will need a piston ring compressor.
Does any one have any tips on how to replace this gasket, see photo.

 ;)

[Guldbergdk]

I dont think you need a piston ring compressor. You can use a ziptie most of the way and there is probably a tiny tiny chamfer on the cylinder so if you apply a little downwards pressure on the cylinder it will hold the ring in place while to squeeze it in all around. At least that worked for me on a BIS engine. It didnt take very long to do for both cylinders

[Iffy650]

That's great thanks for the advice

[ChrisRLewis]

Sounds a very difficult job without removing the piston and the conrod together i.e dropping the sump and removing the big end. If the conrod is left in place you will have to some how install the piston back into the bottom of the barrel.

[Guldbergdk]

Oh. I didnt thought about that. Its from the bottom up

Well, its more fiddly, but I guess it can still be done.

Or take it as a great excuse do do a full rebuild:)

[Iffy650]

Thanks, I'm still hoping that I can slide the barrel up, put the gasket on and the slide the barrel down again but it's just how difficult is it to keep the piston rings pushed in to get the barrel back down over them. I haven't been able to see how much of a chamfer is on the bottom of the barrel yet. I was hoping not to have to a bottom end rebuild as it's all in very good condition. It's just the paper gasket between head and barrel has disintegrated and oil has been leaking out.

[Pete126]

You can't do this job without either disconnecting the Conrods or removing the head and barrels

[Iffy650]

Thanks, got the head off. Any tips on how to to keep the piston rings compressed to then push the barrel back down over the piston (instead of taking sump and big end off)

[Pete126]

You can use the metal from a tin can and a jubilee clip to compress the rings so you can get the pistons back into the bores

[Iffy650]

Great thanks.
Are the paper gaskets ok or does anyone recommend the copper ones for the gasket between block and barrel? Are the copper gaskets thicker and does this make the barrel sit higher at top dead centre?

[ChrisRLewis]

I still think you are going to find this very difficult to do by inserting the piston back through the bottom of the barrel. Perhaps an easier option would be to use a good quality gasket sealant instead, after a thorough clean of all the mating surfaces..

[Iffy650]

Hi Chris, Everyone,
Can you recommend the best gasket sealant to use for this joint (engin ed block to barrels)?
Any advice grreatly appreciated,
Thanks

[ChrisRLewis]

Looks like the VW owners use Permatex Ultra Grey or Permatex Ultra Copper sealant. Few things to watch is that the mating surfaces need to be ultra clean and degreased, the cylinder head needs to be torqued before the sealant goes off and allow 48 hrs or longer before starting the engine.

[Iffy650]

Thanks for the advice Chris