It's actually an interesting point. I'm sure lots of folk will come up with 101 reasons why it's perfectly legal but insurance companies will look for any get-out possible.
It's the same as tyre puncture repairs. The manufacturers of tyre plugs will not guarantee them above the national legal limit. In other words, if you have any plugs/repairs on any of your tyres and you happen to have an accident while breaking the speed limit... It's not going to end well.
I used to run my own motorcycle tyre business. Whenever I had guys coming in to repair punctures I would say yes no problem, but be aware should something happen while your going over 70 (which lets be honest, when a bike can do over 70 in 1st it's a fair bet) your insurance will wipe their hands..