In my case, in order to get clearance above the rocker box bolts AND also clearance between the underside of the rubber handlebar casting and the Smiths Clock bezel (well where the bezel would be if I actually had a clock
) needed a bit of juggling. My instrument panel is a 'made in India' copy but for £25 it will do the job. It needed to be reduced in height so that the petrol cap would go on, so an afternoon with the angle grinder got it down to the minimum height possible for it to still do its job.On a level surface I put the bike on its wheels and with me sat on it I put a spirit level across the front and rear tank mounts. The bubble was in the middle so on my bike the top surface of the mounts are at the same level. To give me 3/16" clearance between the bottom of the tank and the rockerbox bolt heads I needed the 5/8 rubber and 4 x 2mm penny washers (about 5/16") above the mounting bracket. I also needed a 3/8" rubber and thin washer below the mounting.
The nice stainless tank bolts from ACME were of course too short
so I needed to make some longer ones. I got a 5/16 BSW British made HSS die on Ebay for a few quid and then found it was 1 5/16" dia so would not fit any of my dies stocks so another visit to Ebay was required.I worked out that with a 1/4" length of thread to go into the tank mount (having it this length means that even if you bottom it out when tightening it will not contact the base of the tank itself and puncture it) the front bolts needed to be 2" long and the rear 2 1/16" long (both underhead measurements)
I got some 4 inch long 8mm stainless bolts from Screwfix (£4 for 10..a bargain) and made up the four bolts. All I need to do now is drill the holes for the lockwire.
The photo shows the new bolts on the left and the original 1 5/8" long 0579 bolt on the right.
Cheers
Alan