Scooterotica

Yes its as you said the big end eye is catching all the way around, I work for an engineering company so im thinking that ill have 0.5mm skimmed from the bore. Does any one know what the clearance should be?

I don't think anyone relieves the whole bore, a narrow channel is all that's needed and minimum depth i.e. enough to clear. Some people accomplish it with the use of a hand grinder. Also, I'm not sure if you understood Ross's point, he was pointing out that when you rotate the crank through 360 degrees, you need to keep the small end on the centre line of the cylinder at all times. The big end eye might be cast a bit oval and if its allowed to go off centre while you are checking it might give you a false impression.

hi I had a 60mil mec that catched on the casing and I just took alittle off the bigend path in the area of the case it fouled with my dremel then cleaned up with a small flap wheel (again in the dremel).

Sorry maybe I wasn't as clear as I could have been, the 60'mm in my Rapido would catch on the casing if the rod was horizontal when the big end pin was at the twelve and six o'clock positions, but if you kept it in the path of the piston in the centre of the bore it rotated freely. Assembled it rotates fine, no catching.

If yours catches at BDC then as has been suggested you only need to relieve a channel the width of the rod and preferably only where it's catching.

It's also probably worth checking it with the mag flange in just to make sure its centred and true. Paint some engineers blue on the bigeye of the rod and turn a couple of times and you should be able to see where to cut.