Posts
95
Joined
11/22/2021
Location
GB
Hi, I’m planning my first top end rebuild on my 250 sx 2018.
I’ve noticed there are 4 options when ordering a piston.
The bike is on 71 hours, I bought it on 44 hours.
I have no idea if the bike previously had a piston replacement.
The bike still starts /
Runs as normal but during off season now is the time for a freshen up.
Can anyone advise me how you can tell which piston size to choose ?
The barrel has 66-21 R printed on the side if that’s any help.
Thanks
I’ve noticed there are 4 options when ordering a piston.
The bike is on 71 hours, I bought it on 44 hours.
I have no idea if the bike previously had a piston replacement.
The bike still starts /
Runs as normal but during off season now is the time for a freshen up.
Can anyone advise me how you can tell which piston size to choose ?
The barrel has 66-21 R printed on the side if that’s any help.
Thanks
My '19 250 didn't appear to have any marking on the cylinder for piston size like my mrs' older 150 does, but of course the piston had it on top, was visible just popping the head off and looking in.
If you just want to get it done, I guess just sling a B piston in it and call it done, would have been an A or B when new and bound to have worn a touch, it's a very small size difference anyway. I swear that's what half the people I know do, some of them don't even check the ring gap(s) which is kinda worrying. I'd still prefer to measure it and go by that personally though.
It’s best to measure the bore to determine which size you need.
The Shop
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