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The 2-Stroke Garage => Turning Wrenches => Topic started by: KANDY on October 06, 2020, 11:03:28 PM

Title: Question on RD400 Pistons
Post by: KANDY on October 06, 2020, 11:03:28 PM
Hi All,
Quick Question to confirm. Can I use RD350 Piston on 1977 RD400
Thanks
Title: Re: Question on RD400 Pistons
Post by: Yamaha 179 on October 07, 2020, 04:59:18 AM
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
Title: Re: Question on RD400 Pistons
Post by: KANDY on October 07, 2020, 09:07:21 AM
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.
Title: Re: Question on RD400 Pistons
Post by: Yamaha 179 on October 07, 2020, 12:29:30 PM
None at all; in fact that is better.  You know forged pistons require more (looser) clearance, right?
Lyn
Title: Re: Question on RD400 Pistons
Post by: KANDY on October 07, 2020, 02:15:08 PM
Yes, I will maintain the specs needed for Wiesco.
Thanks again Lyn
Title: Re: Question on RD400 Pistons
Post by: quocle603 on October 07, 2020, 02:26:48 PM
I'm confused...Aren't RD350 pistons smaller than the RD400 cylinder bore?  :umm:
Title: Re: Question on RD400 Pistons
Post by: SoCal250 on October 07, 2020, 02:28:56 PM
Quote from: quocle603 on October 07, 2020, 02:26:48 PM
I'm confused...Aren't RD350 pistons smaller than the RD400 cylinder bore?  :umm:
Both are 64mm bore
Title: Re: Question on RD400 Pistons
Post by: Diablo007 on October 07, 2020, 02:36:08 PM
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.
Title: Re: Question on RD400 Pistons
Post by: Striker1423 on October 07, 2020, 02:37:08 PM
Quote from: SoCal250 on October 07, 2020, 02:28:56 PM
Quote from: quocle603 on October 07, 2020, 02:26:48 PM
I'm confused...Aren't RD350 pistons smaller than the RD400 cylinder bore?  :umm:
Both are 64mm bore

It's the stroke that makes up the extra 25cc's in each.
Title: Re: Question on RD400 Pistons
Post by: rodneya on October 07, 2020, 05:28:31 PM
Quote from: Diablo007 on October 07, 2020, 02:36:08 PM
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
Title: Re: Question on RD400 Pistons
Post by: Diablo007 on October 07, 2020, 05:34:48 PM
@rodneya

Thanks for the info.  Seems I oversimplified things in my mind.  There are differences in design beyond the 'tang'.
Title: Re: Question on RD400 Pistons
Post by: quocle603 on October 08, 2020, 11:54:08 AM
Quote from: Diablo007 on October 07, 2020, 02:36:08 PM
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...