Just to document what Ed and I have been discussing offline for the benefit of anyone else reading...
I'm not sure it'll be fine long term, on sub-spec oil. The viscosity may be unusual, but it's not ridiculous. KTM will have settled on that oil spec having analysed the loads on the bearings, carried out a thermal survey and run their durability cycles. Highly likely that the bottom end was originally designed as the 620 or 640 (though I'm no KTM expert) and then the higher firing loads of the slightly larger piston, plus the larger inertial loads of the increased reciprocating mass, and longer stroke lead to a requirement for more bearing capacity. And thicker oil is cheaper than new crankcases. That's all assuming the 620/640 didn't already specify 10w60, in which case the bottom end has probably been re-sized as well. It's unwise to count on there being any "wiggle room" in the design of modern engines - design and development techniques have come on a long way, which is why the performance figures of standard machines have come on a long way too.
Yes, the oil viscosity spec will be most critical when the oil temperature is high (which is why some engines derate a little to protect the bearings when the oil temperature is high) but to expect it to only be an issue when racing is unwise. High engine load and low road speed such as when slogging through sand or mud with luggage would generate higher oil temps than racing where the cooling airflow around the sump/frame and radiator is more significant.
It is true to say that mineral oil changed more frequently is an acceptable substitute for synthetic lube, but there's no substitute for the correct viscosity, low oil pressure is low oil pressure, regardless.
Equally momentary metal/metal contact in the bearings can "heal" and it is of course possible to get away with these things for a while, but I'd be nervous enough about travelling with a KTM (reliability predjudices, some unfounded) without knowing I was jeopardising things by running the wrong oil spec...
No offence meant to well intentioned advice, just my tuppence worth...
I reckon mollydog is right about the electric spec - very unlikely to be any concerns running heated kit, charging the odd AA cell or running heated grips or gloves. Adding a headlamp switch could be a very good idea, too.
Dan (resident engine development geek).
'02 Africa Twin (sold), GSX-R 1000 K5 (sold), '97 TL1000S, '08 DRZ400 SM/S, '92 CRM250
Last edited by djadams; 25 Feb 2009 at 22:43.
Reason: spelling, punctuation and grammar :)