Question on RD400 Pistons

[KANDY]

Hi All,
Quick Question to confirm. Can I use RD350 Piston on 1977 RD400
Thanks

[Yamaha 179]

Yes you can.  You might want to think about it a bit, i.e., you should match brands and types as much as possible to minimize possible problems (except in an emergency) but they will work.
Lyn Garland

[KANDY]

Thanks Lyn, Got a deal on RD350 Wiesco second Oversize.
It does not have the cut on the exhaust side, does that make any issue.

[Yamaha 179]

None at all; in fact that is better.  You know forged pistons require more (looser) clearance, right?
Lyn

[KANDY]

Yes, I will maintain the specs needed for Wiesco.
Thanks again Lyn

[quocle603]

I'm confused...Aren't RD350 pistons smaller than the RD400 cylinder bore? 

[SoCal250]

I'm confused...Aren't RD350 pistons smaller than the RD400 cylinder bore? 

Both are 64mm bore

[Diablo007]

Longer stroke on the RD400.  RD350, RD400, and RZ350 pistons are basically the same; though the tang' on the RZ350 piston needs to be removed before using in an RD.
http://www.greasygringo.com/2012/03/using-banshee-pistons-in-your-air-cooled-rd350400/

Can the RD pistons be used in an RZ350?  Never thought about that as RD pistons seem to be the ones that are hard to source nowadays.

[Striker1423]

I'm confused...Aren't RD350 pistons smaller than the RD400 cylinder bore? 

Both are 64mm bore

It's the stroke that makes up the extra 25cc's in each.

[rodneya]

Longer stroke on the RD400.  RD350, RD400, and RZ350 pistons are basically the same; though the tang' on the RZ350 piston needs to be removed before using in an RD.
http://www.greasygringo.com/2012/03/using-banshee-pistons-in-your-air-cooled-rd350400/

Can the RD pistons be used in an RZ350?  Never thought about that as RD pistons seem to be the ones that are hard to source nowadays.

Rd windows are smaller than the RZ / Banshee pistons, so it would be a downgrade

[Diablo007]

@rodneya

Thanks for the info.  Seems I oversimplified things in my mind.  There are differences in design beyond the 'tang'.

[quocle603]

Longer stroke on the RD400.  RD350, RD400, and RZ350 pistons are basically the same; though the tang' on the RZ350 piston needs to be removed before using in an RD.
http://www.greasygringo.com/2012/03/using-banshee-pistons-in-your-air-cooled-rd350400/

Can the RD pistons be used in an RZ350?  Never thought about that as RD pistons seem to be the ones that are hard to source nowadays.

Thanks for clearing things up for me. I did not know that! I've always thought that the bore was overall bigger.

I've done this. Works great with my build...