Bike struggling to start up

[GSF]

Clearly he must have been sodomising it. There is no other reasonable explanation.

Sounds likely, especially if it's a Honda.

[Gremlin]

If your friend simply started it and let it idle for a while, it's done more harm than good. The battery will only start charging above a certain RPM, and it's more than idle (varies from bike to bike). You'll probably need a new battery.

[FJRider]

And what will I do with this one?

Thrash the tits off it!

assuming ... your friend has tit's ... which could BE the problem or the solution TO the problem. OR take your mind OFF the problem.

Maybe ... nothing to do WITH the problem.

But I'd go with ... it hasn't been started and/or the fuel is stale.

The battery may be down a bit and not winding over as fast to get a quick start.

[ducatilover]

If your friend simply started it and let it idle for a while, it's done more harm than good. The battery will only start charging above a certain RPM, and it's more than idle (varies from bike to bike). You'll probably need a new battery.

All of my 8 bikes have been able to idle at the manufacturers specified idle with the headlight on producing upwards of 13.4V.
Chances are it's not dropping voltage at idle being a late model bike, my GN250 can produce over 14v at idle with the light on, my ZX6 with its Doug wound stator manages 13.8 at idle with the headlight on

It's more likely to be plug fouling, or only run for a very short amount of time to drop battery voltage.

[CookMySock]

Start 'er up and go for an hours' ride. It will be mint when you get back, and so will you.

[Katman]

You do far more harm by starting an engine every few days and letting it idle for only a few minutes than you would by not starting it for 6 weeks.

Take it for a decent run and it will be fine.