All of mine have a thumbnail thick gap on both ends of the clamp. They are snug. Never had one come loose. I'd be afraid that if they were tightened to close the gap something would strip or break.

I might dig around further later, but I'm sure I read that the clamp has one correct way of fitting and that the front bolt is tightened to closed and then the rear tightened as far as it will sensibly go. The later clamps had an arrow cast into them to indicate correct fitting direction. 

I agree that often the instructions are to snug down the front bolt/nut FIRST until gap is closed and then tighten rear bolt/nut.  

You won't overtighten/strip if you do this...  you're just cocking the cap so front edge is closed so all the gap is at the rear.  

Caps with arrows pointing forward have a longer leg on the front half of the cap so the cap doesn't end up cocked as much, if at all.  

I've always thought this was done to help keep out water and dirt?  Not sure though.

I also don't recall if on earlier manuals Yamaha ever mentioned a procedure?  It seems they'd often tell you how to do something like remove the front wheel but wouldn't say anything about installing it.  

 

I have often wondered the same thing when it comes to the saddle clamps/pinch bolts on the handle bar mounts. So I looked it up in my Yamaha manual for my 2017 SCR950 and they described the exact process that Mark stated. Snug the forward screws to solid, and then torque the trailing screws leaving a small gap. I had always torqued the screws to try and maintain an equal gap. Not anymore.

Either way is likely correct.  The first Yamaha manual I found that mentions a procedure for the axle caps is a 1976 DT400 owner's manual.  It actually says to "keep the gaps equal".

Then in 1977 the owners manual says to close the gap completely at the front and then tighten the rear.