'04 Bonnie (carbs) Airbox Query

I'm re-commisioning my 2004 T100. Opened the airbox to check the filter and found it had around 1/4 pint of (clean) oil in the base. Is this normal? The handbook doesn't mention it. If not. where did it come from? The sponge rubber seal on the air filter had perished so a new one is coming. The book's been OTR for over four years.

 

I guessed it wasn't normal, a lot of older bikes had "wet" filters as does my boat engine but even then there's not a lot of free oil in the airbag. Something else to check out. I hope the check valve isn't buried inside the engine casings. Thanks for the tip.

 

The closest the bikes been to "on its side" is "on its side stand".

My guess is either that I didn't drain all the oil on the last oil change, or that because I put in the full capacity before turning the engine over, some got pumped out of the breather before the filter and/or cooler was re-filled by the oil pump.

Got my wheels back from the tyre fitter today and picked up the brake parts yesterday so it's time to put the old girl back on her wheels and down to the MoT station. I'm giving myself a fortnight to sort everything, hoping to get back on the road by 1st July.

I noticed someone has the Haynes Manual. I've got the official "Workshop" manual. I rather think the Haynes one might be more informative.