Sounds like your battery is 'dud' if its only showing 11.8v.
When you put it on load the voltage might drop much lower making it seem like 'no power'
Are dash lights on ? (Oil light etc.) .... if so do they dim when you try to crank the motor over ?
It could be your starter solenoid has stuck, preventing the engine from turning over.
If so you could short out the main terminals on the solenoid to see if that will cause the engine to turn over. If so go get a new solenoid. The 'shorting out' is only a 'test' & not a fix !
As for battery, I guess the bike has been laid up over winter - have you charged the battery over winter. They will self discharge over time & low temperatures don't help. You should check voltage at least every month & do a top up charge if its getting low & before it drops under 12v. A battery should always show over 12v, if not it needs charging. If you don't do that the battery will hold under 12v, but will deteriorate.
Do you have a 'slave' battery you could substitute to see if it solves your problem ?
Could chance jump leads from another bike/small car.
Bike batteries tend to be less resilient than car batteries, & usually when they start playing up it is a sign they are close to 'end of life' & if reliability is important, then its best to change your battery.
Hope that may give you some useful things to test/try out.