Pressure test clutch bubbles!

[CrankyBrit]

I'm still failing to get my bike running right.
I was hoping a straight needle (I replaced the N1EF with a DDJ) and stock (according to CPD) jets would help, but not so much.

So I tried a pressure test, but now I have questions...

The two vents:


...were both blowing lots of air, so I plugged them them, but... Q1) are they detrimental air leaks during normal operation if left open?

Then, bubbles formed from behind the clutch slave. I checked the parts diagram and it doesn't appear that there should be a gasket behind it so I'm assuming something further in is leaking. Q2) what's likely to be leaking air in there?

I'm guessing whatever is leaking will require me splitting the engine to replace it. If so... Q3) what other stuff should I replace in my '01 engine while I'm at it? (the top end may have been replaced 10 hours ago, according to the kid I bought it from, ...who didn't do anything beyond changing the chain as far as I can tell)

I'm increasingly suspicious that there was an issue with the engine that caused a top end failure, and when they replaced the top end they decided to upgrade to a 300. They then did a terrible job of the upgrade (not getting the power valve connected correctly for one thing) and not fixing the underlying issue that caused the failure in the first place, and then gave up on the bike.

So, I'm expecting there's an issue to find that would cause a top end failure. Q4) would a bad air leak do that?

...and who knows what other bad workmanship.

I'm so glad there's a place where people who know about these issues are willing to help us 2 stroke newbies! Thank-you everyone!