Injection block off....

[LMS]

Removed right side cover that houses injection pump to paint and found this... Bike runs pre-mix. The little pipe was just lying in the case which I found fits in the shaft. From what I can tell it's a super tight fit, and my guess is that they could not get it out and left it in the case. After a while it rattled itself free. My question, shouldn't that area be saturated in oil since there isn't a block off plate, or no? There was a little oil when I took that side cover off, but not much.

[The Red Scourge]

If I remember correctly the oil enters and exits the pump and that area via oil lines.  It's been a while since I've had my hands on my rd400 engine, but I think that hole is where the drive gear for the oil injection pump sits

[rodneya]

Looks like there is something at the back of the hole stopping oil getting out.

[KANDY]

They must have blocked that hole by placing a plastic sheet and screw from behind.

[SoCal250]

Appears to be blocked from the inside. Not the usual way it's done. It seems to be effective since there's trans oil on the other side, but ideally you would want a complet seal and no oil coming through.
The small "tube" you found in there looks like the bushing for the pump drive shaft.

[LMS]

Interesting.
On a side note, did a leak down test and it passed with flying colors, was dreading that.
Thx all.