What would folks say an expectable increase in ID when boring out bottom yokes. Have a couple of sets one being an ohlins fitment 56mm and the other 53mm...I'm having either bored to 58mm, however wondering it the 53mm will stand up to having 2.5mm taken off? Obviously the 56mm will be fine with 1mm but would rather use the less expensive of the 2. Having the top yoke bored from 53mm to 56mm..however trust this will be fine as will be less structurally compromising due to the meat already on it..plus less stress etc. Cheers,
I'm pretty sure both bottom yoke 53 & 56mm sizes are from the same basic casting so should be the same either way. Don't know whether there's enough meat on them but would have thought so You fitting some proper SBK forks
I would measure someone else's yokes first to see if they are the same before you assume they are all cast from the same blank. The yokes take an enormous amount of stress which is passed through the upper frame.
The casting on the 56mm is .56 bigger than the 53mm that's all. The 53's defiantly have enough meat to be bored out to 56 however that extra 1mm may be that bit too much! I'll speak to my machinist and see what he says. Struggling to find anything bigger than 56mm in narrow track...all the 58's are for wide track fitments. Don't want to cut corners with this, however my 56mm sold would be more pennies for mods. Not sbk forks as such, however are very meaty ohlins billet bottomed R&T's with 30mm carts. Built thread to follow
Don't forget to check to see if you have enough thread left on them when you mill them out. as you will be removing the effective clamping force also.
