What do these markings mean on the side of the pistons. This guy who sold me 4 oversize Pistons, sent me three that actually were oversize and one was standard. So I told him that I wanted the other oversize piston. I then sent him the STD piston. The Piston arrives today, I break out the micrometer and it is a STD piston measuring 3.4248", clearly a STP piston.

Now he's trying to tell me that HF1 is for the STD piston, and HF2 for the Oversize.

Well I almost bought into that being he sent me an HF1 and the one Oversize Piston I looked at had HF2 stamped on it. But, when I went to check the pistons that I had miced(which I knew were all STD piston) they were marked randomly with HF1 and HF2. Basically telling me that mark meant nothing about it being overbore or standard.

Someone hook me up with some info ASAP!

 

BUMP

 

Well if you bought these pistons for a 400ex or xr400 the hf1 piston is for the 400ex and the hf2 piston is for the xr400 but they are both exactly the same. the only difference about the engines are the head gaskits. The markings are jus to help honda keep track of whats what.