Blow back through the air box ?

After 4 days of trails in North Wales I went to start the bike after a gate and it just wouldn't fire up. Fuel pump, starter all worked fine but I thought I would drain the battery so decided to bump it on the Tarmac hill. 3rd gear and nothing would fire up but it seemed to be blowing air up from the tank area, air box almost popping.
It finally caught and has been fine since but I'm heading away again soon so any thoughts ?
New battery might be required ? Recommendations please, just runs the heated grips and Garmin. Thanks, Simon.

Sometimes the signals to/from the throttle position sensor can get upset, which can cause poor start/tickover issues. Usually sorted by doing a TPS reset (from memory switch off ignition, on again, 3 full rotations of throttle, off again, on again and start normally (or at least it's something like that)

Another problem we've had is one of the wire solder joints in the bottom of the ignition switch breaking down - sorted on the trail by use of superglue, but given the other bits were working on yours I think this unlikely

Re gurgling sound from airbox - mine sometimes does it when it switches off. Not had any problems or oil come up.

Re battery - I'd just get it checked to see if it's okay. I've been using Motobatt which have good CCA, but Lithiums are coming down in price . . . . .

How were the Wales Trails?

Thanks Gareth, the throttle issue is something I had considered and it did start after I switched off and on again. I think for peace of mind I may invest in a new Motobatt battery anyway.
North Wales was fairly hardcore to be fair and I'm not an inexperienced rider. Very rocky in places with some spectacular scenery. We were recceing the TET so some places were a little too tricky for us with soft luggage. The Mitas E09 Dakar on the back with the more knobbly Mitas on the front did the trick though.

I have seen a bike with a sticking idle control valve that made some strange noise under cranking as it tried to pull a vacuum with the throttle shut. After it was keyed off and on, all was fine. its an easy one to remove and clean out. maybe worth a go.

sippingdiesel said:

I have seen a bike with a sticking idle control valve that made some strange noise under cranking as it tried to pull a vacuum with the throttle shut. After it was keyed off and on, all was fine. its an easy one to remove and clean out. maybe worth a go.

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Thank you, rode today and no issues !