I recently bought a 1988 250r from a buddy that he was having trouble getting it to kick start it came with a 1988 310 engine and the engine on it is suppose to be a 1986 with a 265 kit I tore the engine down and the exhaust side of the piston was missing I was thinking that it had a blowed head gasket and it caused it to melt the piston but I’m not sure the engine has a spacer plate under the cylinder so I’m assuming it has the long rod in it but I’m not sure I cleaned the cylinder up and it seemed to clean up nice so I was gona put a new piston and rings in it but I’m not sure what year piston to get I googled the numbers on top the old piston and came up with a 68 mm wiesco 1986 piston but I was just wanting to try make sure that was the year piston I needed and the reason tgat it broke or melted was not because someone had the wrong piston it any advice would be greatly appreciated
that is a short rod crank Justin posted from an 86 ATC TRX 250R if it says HB9 on crank it is from an 87-89 Honda TRX 250R and will be long rod and if it said KA$ that would be from an 85 ATC 250R also short rod.
Not very familiar with hot rods cranks but post any identification number that are on crank. I am sure Carlos will chime in he know a great deal about these bikes!!
that looks like a long rod crank with a short rod piston.do you have a picture of the other intake side of the piston.long rod piston has a square hole and a sr piston the bottom of the skirt is a u shape.from left to right.sr stock piston..sr big bore piston long rod piston. and all cylinder are a touch different but a spacer plate isn't needed unless a stroker crank,or 70mm+yz250 piston
I will post that pic when I get home from work when I set the cylinder and head on there without the spacer plate the piston hits when it gets to the top I appreciate all the help I would be lost on what I have without all of the help