TOPIC:

So, two questions: What is this stuff? and. How do I get it off?

I'm trying to replace the cylinder bottom gasket, so I want a nice clean surface. But around the cylinders are these hard, green deposits. I have tried engine degreaser, engine cleaner, acetone, plastic scrapers, scotchbright pads.  .. Some of the looser stuff came off, but there's still a lot left. Anything else I can try?

 

That is just part of the gasket stuck to the case, some gaskets are impregnated with sealant and that is the result of being baked on after time, and yes, it is indeed hard to get off.
I had the same problem on my 650. I ended up using automotive paint stripper and a small artists brush and carefully painted it onto the baked on bits and left it to do it's thing for 30 minutes then used a single sided razor blade to scrape it of. It came straight off, really easy. It is imperative that you clean up afterwards, I used a damp clean rag then acetone then another clean damp rag. You don't want to leave that stuff on the surface as it's pretty gnarly stuff. Likewise you don't want any going into your motor so make sure all avenues into the motor are blocked.
Mine was easy to do as the studs were removed and the cases were split so I suggest you only do it in sections because believe me your fingers will be killing ya!
Also, was that gasket leaking? Being green suggests that it may have been an Athena gasket. The general consensus here is that Athena gaskets are shit and will definitely leak.
Good luck.

Permatex produces 'Gasket Remover' in a squeeze tube.  We've had success with that.  Aircraft Stripper works too.  Wear chem-proof gloves.

Small woodcarving chisels for detail work with long, angled shanks and flat blades can get into tight areas more easily.

No matter how hard one tries, gasket debris will follow gravity.  Pack openings tight with rags or newspaper.  When done scraping, use a vacuum to pull debris out from the packed areas before and during removal of the packing.  Take your time, and droppings will be kept to a minimum.

Good Ridin'
slmjim & Z1BEBE

I've had some success with oven cleaner, but ultimately it boils down to lots of scrubbing and wiping.  I use stiff brushes...anything that will not scratch the base surface.  

Or...if you prefer you can split the cases and take them to be aqua blasted.  

Looks like you about got it. Consider dropping the pan and spraying out the inside. Pan and pump screen will thank you. I cleaned it out without spitting the case and you could a ate off it,,,, (well almost). I agree on staying away from the green gaskets too lotta trouble reported on them on here.

wrote:

Also, was that gasket leaking? Being green suggests that it may have been an Athena gasket. The general consensus here is that Athena gaskets are shit and will definitely leak.
Good luck.
 

Interestingly, it wasn't leaking. (I'm only replacing it because I accidently broke the seal on it while removing the cylinder head). The gasket I removed was black and broke into quite a few pieces in trying to pry it out. 


Thanks for the tips, everybody! I'll go pick up some more cleaning products and hopefully something works. 

Heavy duty paint striper is what I recommend.  The stuff that cleans off with mineral spirits, not water.  Permatex gasket remover used to be good but the low VOC version is garbage.  

I picked up some Aircraft Stripper and went at it a couple times and still can't get it off. This is some stubborn stuff!

How long did you leave the stripper soak?  It works best if you keep the surface wet and allow it to dwell for a half hour or so.  Even at that it may take a few applications.