EC300 Which piston size?
 

Hi all

I have a 2004 EC300, I bought it and have run it for a while. I now want to replace the piston kit, just so I know where I am with it.

I know nothing about the history of the bike or what parts have been replaced.

1. The cylinder is marked 'A' so should I simply fit an 'A' size piston?

2. Are the pistons also marked with a size/letter?

I'm afraid I don't have easy access to accurate bore gauges to measure the actual size of the cylinder.

I'm not looking for absolute maximum performance, reliability is more important to me.

Thanks, Dave.

Update...
 

Just an update...

I removed the cylinder head today.

The plating looks to be in good condition, can't see the honing marks but also can't feel any lip at the top of the barrel where the rings/piston reach their highest point.

If I put my finger on top of the piston, I could rock the piston backwards and forwards quite a lot, seems excessive to me, so I assume the piston must be pretty worn.

Photo's?
while the cylinder is off, take it to a shop near you. If you do not have proper tools to measure.

I didn't realise my piston size is marked on the crown, I could only see it after cleaning off the light coating of carbon.

It's a B size and I've decided to fit another B size 71.94mm.

All the best, Dave.

IMHO if you don't see any hone marks it's wore out and needs to be re plated. At least that's been my experience.

Jeff Slavens says to check for a ridge at the top of the cylinder to estimate cylinder wear.

https://www.youtube.com/watch?v=vaFp8aYkHNA

Strictly speaking you'd find someone with a proper diamond hone used to doing plated stuff to hone it and measure.

But it's an 04. Scotchbrite (plastic pot pad) it and fit a B and go enjoy it.