Exhaust coming out of sprocket cover.

So my little 2-stroke has been quite the champ. I'm hard as **** on it, and it's lasted me around 12,000 miles. All I've done is change out the cylinder/rings once.
Anyway, now it's having a weird issue. Not sure if it's a problem, but it's weird.

When I first start it up it smokes really bad, so I let it warm up for a min or two to let it get going. Probably needs to be re-ringed again. But lately I've been noticing smoke, looks like it's coming out from the chain sprocket cover on the engine!!

So I put my hand over the exhaust pipe and held the throttle open at the same time. Sure enough, the engine bogged way down, barely running. But did keep chugging along dumping smoke out of sprocket cover!

As I said, it probably needs a re-ring again. It's been a couple years, it's a bit low on compression again. Still ride it daily, and it runs pretty decent though.
But I've never seen that before. What's wrong?

Probably.... any suggestions as to which ones? Or if I should even bother with it, just keep riding?

It's a bit down on power lately :/
I was assuming it was rings again. The first time I replaced the cyl the ring pin had come out and eaten the cyl wall, piston, rings. So I replaced all that stuff. Then something got in and scored the cyl wall on the second jug. Not sure how that happened.
But I have probably 5000 on the current top end, just figured that was why it's getting slow again. But maybe it's this leak

I think I have a spare head gasket if the one on there now can't be annealed, I'll put the head tomorrow and take a look.

How bad is it to split the case and replace all the seals. ANd while I'm in there, bearings and stuff?

Ibedayank said:

there is a gasket that runs the length of the case halfs
if you split the case you will see that there a wall that seperate they cylinder area from the clutch shaft and bearing area there are no seals on the clutch shaft.
The new gaskets are much better then the old ones.

Click to expand...

How bad a job is it?
Maybe I'd replace the bearings too if I'm in there. Just sucks it had to happen right as it's getting warm out.
As long as I don't run lean, I doubt it's hurting anything though.

Thanks for the great pics! That's a great guide.
And thanks for the link with parts availability.
I was just gonna make my own gaskets, with either gasket paper or permatex anaerobic sealer. I rebuild subaru engines (Boxer design. So splitting crankcase, etc. Major pain). And that's how I put them back together.
This should be a fun little project compared to a car motor!