wheel spacers
 

i have a classic with 3mm spacers on the front (to clear brembos)as they are only 3mm will that matter if i do a track day cheers mike

Nope, that's such a small amount it wouldn't have any adverse effects.

i ran 25mm spacers and incorect spigot rings on an old car... then i managed to snap a stud. 3mm you wont have any problems with

i'm running 3mm on both front an back on mine, an i've never had any issues ( apart from the tyres rubbing in the arches, on full load )

Make sure you have enough threads left in the wheelnuts. IIRC criteria is 1.25 times thread diameter so about 15mm worth of thread or 12 turns of nuts on a 1.25 thread pitch.

All 4 of my hubs have longer bolts in them. Annoying really cause I can't put captivated nuts on because of the length