Are oversized pistons available for 1970 360?

Yes.

Check out CMSNL, Partzilla etc and/or the parts manual in the Tech library here for the part number. You can then post a request for what you're after here, search fleabay or CMSNL (they have three of the four over sizes in stock) and Partzilla for them.

You will need the correct rings to go with them and it's good practice to also replace the top end bearing, wrist pin and the two clips.

Find an engineering shop that is familiar with re-boring Yamaha two strokes. Also, before buying any parts, show the cylinder to the machine shop and get them to advise which over size you need (deep score marks might not come out with just one size up).

When buying, go with the size that is stamped on top of the piston (0.25, 0.5 etc), not what is shown on the box it comes in. Also make sure that you buy a 360 one, not 250 - some sellers say that the same piston fits both!

What size is it on now, if not standard 80mm. Look on Ebay but be careful of sellers peddling reed holed pistons as RT1 pistons which have 'no' holes. Yamaha still ran RT1 engine prefix up to RT3, & RT2 & 3 have reed holes. Hope that's not too confusing. Confused myself lol.

It's marked 8100, and slightly sloppy.

Rendering Error in layout Message/Item: fopen(http://open.api.ebay.com/shopping?callname=GetSingleItem&appid=makotosu-08bc-47da-8e7d-68e3ee6e51ca&siteid=0&responseencoding=JSON&ItemID=372872650896&version=889&trackingid=&trackingpartnercode=9): failed to open stream: Connection refused. Please enable debug mode for more information.

Please Log in or Create an account to join the conversation.