Revived a wrecked bike, Smoky Startup

[jjwithers]

A friend got hit pretty bad on his 78 R100S.
The engine was not damaged, but the front end and frame needed work.
I had the frame straightened, put on a new front end, put the bike back together after cleaning and panting, etc..
The bike has sat for about 2 years without running in a wrecked pile of parts. Most likely with the engine sitting at an angle.
I put all new oil in, new oil filters, and I built up some oil pressure by running the starter without the plugs.
I checked the valves and timing and they are perfect. Threw new plugs in.
I started it up today for the first time and it fired right up. However, some serious blue smoke started coming from the right pipe, and eventually the left. I ran it for about 20 seconds and again for about 30-40 seconds. Then I had to go in for dinner and take care of family stuff...
As soon as I can touch the bike tomorrow, I'm on it.

I'm wondering, since the bike sat for so long, could this just be gunky old oil burning off? or I worry that the rings and cylinders are no longer doing their job and oil is coming through an burning.

My big worry is seizure...
So, to the gurus out there, what are your thoughts about this happening to a bike sitting for so long?

[Zombie Master]

I'd run it longer to see if the smoke clears.

[hudson]

If not clearing, perhaps try a leakdown test?
Air escaping from:
intake (remove carb) = bad intake valve
exhaust (remove header) = bad exhaust valve
remove oil fill cap = bad rings

[Kurt in S.A.]

Broke a ring? Could have rusted to the cylinder wall and the initial start up broke it off. That leak down test will tell the story.

Kurt in S.A.

[jjwithers]

I fired it up today. Much less smoke to eventually no smoke after a 1 minute idle.
All is well... for now. Going to tune the carbs and see how that goes. Thanks guys!

[dwerbil]

I fired it up today. Much less smoke to eventually no smoke after a 1 minute idle.
All is well... for now. Going to tune the carbs and see how that goes. Thanks guys!

Imagine it has cleared it's throat so to speak. Typical to smoke a bit after a lengthy pause. Zombie is right.