X2 on everything blaner said.
ehemmm....cough-rep-cough...
i think that damage is fixable in the manner you suggest Sic.
Motocrosmaster, you go about the chamfering process firstly with GREAT caution. one slight slip of the hand and that cylinder is toast.
I like to use a dremel with the flexi shaft extension, it lets you get in there, i wouldnt try it with just the machine with a bit in the end..too clumsy
I like to use those orange medium grained grind stones with the conical shape. they give you an advantage in terms of the angle you need to achieve with chamfering.
Your primary focus in the exhaust. Start there: lie the barrel horizontally on a work bench so the exhast port is flat on the bench. so you can see the port facing you. carefully guide your grinder in the cylinder (start at either end) ...be careful! when you have it in position to grind, hold steady and move your head so that you can look down the cylinder from the other side, so your hand is in one side and your head is in the other! this way you can watch what you are doing.
Gently grind the port edge in a smooth, flowing motion from left to right, right to left, do this at the flattest angle you can achieve. use the specs in the pic above for a guide. you want 2mm up the cyl face and 0.5mm into the port. this will give you the right bevel.
Repeat this proces from the other end of the cyilinder so you chamfer both top and bottom of the port. remember to do the sides too.
Do this for all the transfer ports as well, but since they are small, they are less critical.
Your intake windows do not need to chamfered as your rings never pass the openings of them. however, debur them lightly anyway.
Hope this is clear enough!
