Low compression question

[rustybronco]

I suggest you put GM top engine cleaner in the tank, ride it for a few hundred miles or more and then re-check those compression numbers before tearing the engine down.

[GS1000G Shopper]

Sounds good. I'll fix the head and give that a try.

[rustybronco]

I'm not saying that tearing into the engine is unwise. after all, those gaskets, o-rings and seals are thirty years old.

[GS1000G Shopper]

I like the "If it ain't broke" line of thinking, but usually fall prey to the "while I'm at it..." mentality in my projects.

I got the head pulled this morning. Not a bad job at all. Now to see if my welder buddy can fix it.

[rustybronco]

While you in there, don't forget the base gasket, o-rings and valve stem seals. 'twood be a waste otherwise.

[GS1000G Shopper]

I think if I go to the trouble of pulling and reinstalling the cylinders, I'd go ahead & re-ring it. I'm not going to push my luck or budget on this. The gasket set I'm looking at has the valve seals in it, so I will probably do those.

Speaking of gaskets, is one type of head gasket better than the other? I see a bike place here in FL is selling all copper gaskets for the 8V motors. The one I pulled off was a composite type with gasket material and metal rings, plus copper crush washers on the 4 corners.

[mlinder]

Copper gasket is great for moving heat from the head down to the cooling fins on the jugs.
Also great for running boosted or very high compression motors, because they don't 'blow' like the composite ones under those conditions.
Composite gaskets are better for stock bikes. They seal better, especially on engines who's surfaces haven't been recently machined to be perfectly flat without irregularities. Also, they do not have to be annealed, unlike the copper gaskets.

[rustybronco]

I think if I go to the trouble of pulling and reinstalling the cylinders, I'd go ahead & re-ring it. I'm not going to push my luck or budget on this.

I think you already are pushing you luck by not at least replacing the base gasket and the cylinder o-rings. my base gasket was as hard as a brick @ 33K. not to mention it ended up in a "boat load" of pieces when trying to remove the head.

Speaking of gaskets, is one type of head gasket better than the other?

The general consensus is to use OEM gaskets only.

**edit*** too bad it wasn't a few days ago, I would have suggested this kit to try. http://cgi.ebay.com/ebaymotors/1980-...Q5fAccessories

[GS1000G Shopper]

My wife says never say never. Click here.

(That seller has a store & a buy it now for the same price as that auction, and the gasket set was a lot less than anywhere else I saw it)

I'm not sure I'm on the same page with the base gasket. My head came off w/o disturbing the cylinder assembly. Is it necessary to mess with this gasket between the cylinders & case?

Edit
Just realized the seller is in the same town as where the bike came from. Small world.

[raistian77]

Paul,
Did you test the compression with a warm engine? Makes a difference. Also, yes the head will come off without pulling the engine. I've done it twice on the same engine.

The first time I ever ran a compression test on mine I did it cold got 80 across the board. Started to panic then saw the part in the manual that the engine needed to be at operating temp. Redid the test and got 130 across the board.