No matter what, change them both while you're in there! Don't go cheap and only replace the blown one!
I haven't had to change any bulbs on my F3 yet, but my MC also has twin headlights, and I have had to change those.
When changing the bulbs on my Kawasaki I always changed em both out, even though only one was inop. I'd save the one good bulb and the next time a bulb went out, I'd replace it with this 'spare' bulb.
Changing headlight bulbs on my MC was fairly simple though..
Lots of the time the old bulb will not last very long after putting it back in service, at least that's my experience.
^ Agree!! ^ And at the risk of boring those who already know, but in the interests of helping those who might not...
Generally, if one headlight in a pair of globes on the headlight circuit goes, the other globe on the circuit will then have been exposed/subjected to some rather high current/loading thru the circuit intended to have the resistance of
two globes converting energy to heat & light rather than just one, so that one remaining 'old' globe is now not only old, possibly a little dimmer, but also compromised and likely to fail sooner rather than later. In the past, when globe manufacturing wasn't quite as 'advanced' as it is these days, that'd mean replacing just one globe in a pair meant that you'd expect the other to fail in pretty short order. That's not
quite so much the case these days of higher quality filaments &/or LED lights, but it's still an issue to a noticeable degree, only you've generally got a little more time before the unchanged light fails. It's basically the same as sooo many other things that operate in pairs on our vehicles, like the tires on one axle; or better yet, the brake discs & pads on the one axle, different sides - if you kill/damage just one side of the pair, you still really need replace both sides at the same time, or you risk some degree of uneven wear/performance and possibly even unintended & potentially dangerous consequences!!
Aaaand, that means that if you blow one globe in the pair of headlights, leaving you with just one headlight for anything much more than an hour or so, and then only replace the blown globe instead of the pair, like you
should, then your 'old' globe
has now been compromised, so it's likely to blow sooner rather than later... And while you might
think you got away with swapping out just the dead globe, at least for a while, when it does eventually blow, it
will be sooner than expected in its potential life, costing you in terms of money, effort, and time sooner than would've otherwise been strictly necessary, as well as potentially putting you and any other road users around you at greater risk; all of which
will in turn compromise the other 'newer' globe; so now
that globe is likely to blow sooner rather than later, compromising the
other globe and likely causing it to blow sooner rather than later; rinse, repeat, and so on... ad nauseum, and often in an ever decreasing time cycle, with increased costs in terms of money, effort, time,
and potential risk, every bleedin' time!
And all that can happen just because you didn't replace
BOTH Headlight globes in the pair at the same time as you should have done!

But that's OK, it's your Spyder and your money et al, and you will have saved yourself some money, effort, and time (as well as increasing the risks facing you and any other road users around you) by just replacing that one blown headlight globe initially instead of swapping out the pair, won't you...
