[DouginEasternWashington]

You will be surprised at the amount of sludge that builds up but doesn’t come out the drain. Thumper gives you good advice. The motor I just put in my bike had only 6000 miles on it and it even had sludge build up. I’ve been told that sludge can develop from a motor sitting for extended periods of time with oil in it.

 

[CXPHREAK]

Fill your motor with cheap supermarket oil.

Run for a short while, go for a ride if you can.

Then dump the oil and put something decent in.

 

[Roboforcer X2000]

Cheers lads, I'll open up first and then we'll see.

Fill your motor with cheap supermarket oil.

Run for a short while, go for a ride if you can.

Then dump the oil and put something decent in.

I was kinda leaning towards that option...

 

[DouginEasternWashington]

You’ll most likely be fine doing that but it is so easy to remove the front cover in the current state of disassembly you’re in. You could properly clean the oil pick up screen along with any sludge in there.

 

[Thumper]

Removing the front cover might be good enough and can be done without removing the engine.
It just seems to me you might as well pull the engine and give it a good going over.
I've only rebuilt 4 of these engines but removing it makes everything much easier.