Q Should I polish out marks on my Blade’s bores?
My 954 Fireblade has worn and scuffed bores at the bottom, plus similar lines on the pistons’ skirt thrust faces. It’s a shame as the engine was always serviced, but I hear it’s a common problem with 954s. I picked up a low-mileage set of pistons and crankcases with better bores, but still have very slight running marks on the bottom of the bores that can just be felt with a finger nail, similar slight marks on the piston skirts too. Pre strip down it was running fine, so should I attempt to hone or polish these marks out or leave well alone? Fred Skinner, email
Answered by Steve Hammond, Motrac Race Engineering Ltd The CBR954 had an integral cylinder block (i.e. it forms part of the top crank case) and this makes them more challenging to re-plate. Scuffs and scoring was common in Honda blocks at this time. Honda went through a phase of using Alusil-type bores which used aluminium with a concentration of silicon carbide in the surface. Effectively this ran aluminium against aluminium and the hard particles provided resistance to wear. This often led to bore scuffing in the contact area of the piston. The good news is that they can be improved by having a nickel matrix coating applied plus Honda used to offer a 0.25mm oversize piston for some of the Alusil models. This gives the option of precision-honing the bores.