1981 GS550T - splitting cases question

[mike_of_bbg]

OK, you should be golden then. I had no luck beating it with the mallet. Using bolts through the jack points as shown got it done in just a few turns (this is the front one, under cylinder #3 - there's also one in the back).

[D-Mac]

OK, you should be golden then. I had no luck beating it with the mallet. Using bolts through the jack points as shown got it done in just a few turns (this is the front one, under cylinder #3 - there's also one in the back).

Thanks! I've read that this technique works, and the pic is very helpful.

I'm trying to set aside some time to spend in my shop tomorrow night. I'll post my results (hopefully some nice shots of an open crankcase).

[D-Mac]

It's off! A small nut and bolt at each jack point, two turns and it came right off. Now to check the crankshaft, pull my main engine, and get it apart.

***Anyone here ever swap cranks without pulling the whole top end? I just rebuilt the whole top end and I'm not excited about ordering another head gasket (and base gasket). There is quite a taper on the bottom of each cylinder...I wonder if I could feed the pistons up.

[mike_of_bbg]

Congrats on getting the cases split. That threebond is pretty good stuff.

My top end was already apart when I split my cases. I imagine that it could be done though (feeding the pistons from the bottom). You'll at least have to pull the cams and the tensioner to take the cam chain out with the crank: and don't forget to put it on the replacement crank!

Just out of curiosity, what's wrong with the crank? Mine was twisted. If you replace the crank and have not bought the replacement yet, watch the clutch basket gear side. The earliest year or two had straight gears before they went to bevel gears.

[Toasty]

I suppose you could remove the crank without getting a new head gasket, if you kept the top end torqued. I bet it would be a giant PITA to feed the pistons back into the liners though.

[D-Mac]

Yup. Crank is twisted. I was having some issues with timing, and after ruling out carbs, verifying cam timing, and checking ignition/electrical, I dropped a dial indicator down the spark plug holes for #1 and #4. Sure enough, I discovered that #1 is way off (it hits TDC at the point when crank mark is lined up with the firing point, whereas #4 is exactly at TDC at the correct "TDC" timing mark). Took me a bit to realize this problem since compression was still high enough to be "good" (albeit lower on #1 and #2), leak-down was OK since the valves would still close, and the bike started and ran for a several seconds before things started to sound ugly (backfiring through carbs, etc) I should have noticed this when I re-did my top-end, but at the time I wasn't sure what to look for. It's obvious enough now.

Both bikes are 81s, so I should be OK (of course I'll check my "new" crankshaft - including play and run-out).

On these 550s the cylinder sleeves are really tapered at the bottoms. I've tested sliding in a piston from the bottom (with my spare set) and it seems to work. Of course lining up all four at once and pushing them in might result in a broken ring somewhere.

Ah screw it. I guess I'll just pull the top end again. As you say, I gotta loosen the cam chain anyway to get the crank out. If it wasn't for the $90 I have to spend on another head gasket, I wouldn't hesitate to do it (my complete top-end rebuild currently has exactly 0 miles on it). I guess I've come too far to take chances now though.