Do you need to know the marks on the belt slack hole on belt guard. I get that that does not really make sense but what are the measurements in that hole? And when im adjusting the belt slack and rear wheel alignment do I do the belt slack first or the rear wheel straight? Can I use a tape measure for to get it straight?
If you hold up a ruler to the marks in the window on the belt guard, I think you will see the marks on there are metric (i.e. mm’s/cm’s), to help you measure belt deflection/slack when you apply the required pressure.
I’ve attached two screenshots from the actual workshop manual - hopefully they help. They explain the whole process, and show the required torque specs for the axle nut etc.
If you want to ‘freestyle’ it (ie you don’t have the required gauge to check slack), an old Harley guide used to be, you should be able to ‘twist’ the belt about 45 degrees when you grab it.....any more, and it’s too slack, but if you can’t twist it that much, then it’s too tight.
As for your next question - which do you do first - wheel alignment or belt slack.....that’s the trick......you need to do both!!
I think I usually try to get the wheel straight first, and then adjust the belt slack, adjusting each side equal amounts accordingly (and thereby hopefully retaining the wheel alignment you’ve just sorted!!). In reality, you sort of muddle through, doing a bit of both at the same time, trial-and-error like. You’ll figure it out 👍
Ben