1984 300R - What piston is this?

[cduemig]

I recently bought an 84 250R with a hondaline 300r kit in it. The previous owner said it overheated and blew the head gasket but was otherwise fine and had a recent bottom end rebuild. Anyway, I popped the top off today and found the piston froze in the bore when it overheated (though moves fine now). Anyway, the piston is pretty wrecked. I might be able to reuse it, but I'd like to replace it. The machine shop said the bore looked fine.

The piston I took out of it had stamped on it 77.44mm. Thats quite an odd size. The stock hondaline was 76mm and the flowtech mod w/ 330ex big bore should be 77mm if I'm pretty sure. It has a W stamped on it and shop said it looked wiseco. The two numbers on it are 8944 and 1819J. Any ideas? Any suggestions to go from here?

[bcredneck]

post pics of the pistion and check it with a micrometer if its still round you can just get rings

[Yamaha_Rules69]

Its not 330 (ex) ex = 4 stroke. It would be a TRX 330 big bore kit you were thinking. Its hard to say what piston you have there. The stock 300R jug can be bored to a 78mm I believe, that piston is probly considered 1.50mm larger, so I believe you can go to 78, which would be the final bore, but finding the 300r pistons are hard I think. Possibly Wossner may have a piston for it. Go over to air foolers dot com and post your questions. Those guys over there know all about these models. Good luck!