125-200cc 144 piston and cylinder wear over exhaust port

hi pulled my exhaust off today to check the cond of my piston discovered it had wear marks light scratches so ended up taking the top end off the cylinder has worn the plating off inbetween the exhaust valves is this a common prob??? would this bee a reoccuring problem?? i have the eg 144 kit the rest of the cylinder was fine. took it to the bike shop they said it was from heat and it happens from time to time i am getting the cylinder re chromed. also the weights on the crank have little chuck taken out of them must be from a previous blow up the bike shop said not to worry as long as the conrod was tight. any help would be great!

I should not be commenting on this because I have no first hand experience. However, I have read on this forum that the EG kits are not chamfered well which causes early failure. Get it replated and chamfered by a good company and you should be ok.
GP

i am getting the cylinder replated i spoke to the replated he said he will make the bridge between the exhaust ports thicker so hopefully this will not occur again. they are a good company so it should be done corrctly this time around.

If the bridge is less than 3mm wide it will grow and swell inboard and can start to wear on the piston. Can buff off some material on the face of the bridge to give more clearence for this. Also if not done on the skirt of the piston drill a couple tiny holes for bridge lube and cooling.
Later George

thanks for all the info, they are a well known company and they do big bores themselves also warranty there work for 6 months when i go to pick the cylinder up i will make sure he has done what you guys have mentioned. the piston was a eg wiseco 144 it had the oil holes maybe the plating wasnt done right the first time.

I always drill an extra hole in the piston for more lube on the bridge. Keeping the ring fresh helps aswell.

do you drill the hole inbetween the 2 or do you drill it below the lower one? will this weaken the piston at all?

Only drill the holes if the piston 1st has a bridge in the exh port 2nd doesn't have any already.
Later George