RD350 V's RD400 Cylinder Heads
Moderator: rztom
RD350 V's RD400 Cylinder Heads
Hi,
So i purchased a dismantled 1975 RD350 and have nearly finished the restoration. I went to buy some spark plugs and the standard plugs are B-8HS. short reach or 14x13mm (1/2"). However the cylinder heads are long reach or 14x19mm (3/4"). This is odd I thought. So I found the RD400's have long reach spark plugs B-8ES.
I'm guessing at some stage I think the cylinder heads on my RD350 have been swapped for RD400 heads.
Is there any way to tell the difference between 400 and 350 heads.
Will it have any affect on the compression ratio or performance of my RD350?
and if this is a stuff up, do you think my RD350 will miss out on that stunning acceleration with RD400 heads on, Would RD250 heads be a better option or are Rd250 heads the same as RD350 heads?
Hope someone can help
Best regards
Mark O
So i purchased a dismantled 1975 RD350 and have nearly finished the restoration. I went to buy some spark plugs and the standard plugs are B-8HS. short reach or 14x13mm (1/2"). However the cylinder heads are long reach or 14x19mm (3/4"). This is odd I thought. So I found the RD400's have long reach spark plugs B-8ES.
I'm guessing at some stage I think the cylinder heads on my RD350 have been swapped for RD400 heads.
Is there any way to tell the difference between 400 and 350 heads.
Will it have any affect on the compression ratio or performance of my RD350?
and if this is a stuff up, do you think my RD350 will miss out on that stunning acceleration with RD400 heads on, Would RD250 heads be a better option or are Rd250 heads the same as RD350 heads?
Hope someone can help
Best regards
Mark O
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Re: RD350 V's RD400 Cylinder Heads
You cannot do much better than asking (Ed Earlenbach), you can P.M. him here he is member listed as EE. Give him details, and you will have most all your answers.
You can also contact in no particular order (Harry Klemm) @ Klemm Vintage, or (Scott Clough) @ SCR racing. And finally Gary Shumanke @ Spec 2.
These men are likley the leading guys in America for RDs, and likley once there gone..there knowledge will be lost as well. These guys are...the some of the best of the best.
You can also contact in no particular order (Harry Klemm) @ Klemm Vintage, or (Scott Clough) @ SCR racing. And finally Gary Shumanke @ Spec 2.
These men are likley the leading guys in America for RDs, and likley once there gone..there knowledge will be lost as well. These guys are...the some of the best of the best.
Banshee (Baja) race bike,+ 2 A Arms,L.E.Ds, Toomey, +4 stroker IMS tank, run flats.
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96 GSXR SRAD, Future Yoshimura rep.
85 custom Tri-Z
RZ/YZR bike(project)
86 VFR750 RC24 Merkel replica (project)
Royal Enfield Bullet 500
Re: RD350 V's RD400 Cylinder Heads
Ed's HP:
http://erlenbachracing.co" onclick="window.open(this.href);return false;
http://erlenbachracing.co" onclick="window.open(this.href);return false;
Bye
Martin
Martin
Re: RD350 V's RD400 Cylinder Heads
Hi Martin,
Many thanks for your help on the best contacts on this head issue. I'll send them a message. It's a pure annoyance (I'm being polite) that I have got so far with this restoration and was close to getting it running before Christmas only to find someone prior to my ownership has mismatch things.
Thanks
Mark O
Many thanks for your help on the best contacts on this head issue. I'll send them a message. It's a pure annoyance (I'm being polite) that I have got so far with this restoration and was close to getting it running before Christmas only to find someone prior to my ownership has mismatch things.
Thanks
Mark O
Re: RD350 V's RD400 Cylinder Heads
The 400 head has a larger compression dome visible on the outside.
Swapping 400 heads is a popular upgrade to use the 400 copper head gasket.
Do a google search for rd350 head and look at the images. The heads are quite different.
Swapping 400 heads is a popular upgrade to use the 400 copper head gasket.
Do a google search for rd350 head and look at the images. The heads are quite different.
Re: RD350 V's RD400 Cylinder Heads
Hi Bitzz,
Yes Im just working through that as I'm told the fin arrangement is quite different and 400 have a lower compression dome. Sucks that i have someone elses mods. I'm not confident it will ever perform like the ballistic 350's with the lower compression head. However my heads do not protrude from the barrels by a half inch like the 400 as supposed to. So its still an odd thing.
Thanks for your help. Can I attach a photo on here without it being on a web site?
Yes Im just working through that as I'm told the fin arrangement is quite different and 400 have a lower compression dome. Sucks that i have someone elses mods. I'm not confident it will ever perform like the ballistic 350's with the lower compression head. However my heads do not protrude from the barrels by a half inch like the 400 as supposed to. So its still an odd thing.
Thanks for your help. Can I attach a photo on here without it being on a web site?
Re: RD350 V's RD400 Cylinder Heads
Fit the heads. Check the squish clearance with some solder wire through the spark plug holes. Front back and both sides.
If the minimum is between 1.0mm and 1.4mm then ride it.
If the minimum is between 1.0mm and 1.4mm then ride it.
We race RDs, RDLCs, RZs, TZRs, TDRs and TZs at PCRA
Re: RD350 V's RD400 Cylinder Heads
some photos that might help. But I have been advised these might be peculiar to New Zealand / Australia and be 350 heads with a long reach plug
Re: RD350 V's RD400 Cylinder Heads
dam looks like the photos didnt attach sorry, I'll keep trying
Re: RD350 V's RD400 Cylinder Heads
RD400 heads are supposed to over hang 350 barrels, These do not
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- 350 heads overhang none.jpg (244.19 KiB) Viewed 4087 times
Re: RD350 V's RD400 Cylinder Heads
Casting number 52100, I'm told are not RD400 casting numbers. And the other pictures show short reach and long reach plugs fitted.
Hope this helps
Hope this helps
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- 350 head long reach plug fitted.jpg (67.9 KiB) Viewed 4086 times
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- 350 head short reach plug fitted.jpg (204.13 KiB) Viewed 4086 times
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- 350 head casting number.jpg (219.68 KiB) Viewed 4086 times
Re: RD350 V's RD400 Cylinder Heads
400 heads should have A1A cast into the bottom side of the head. Look close at the raised area in this picture.
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- image003-611x458.jpg (103.59 KiB) Viewed 4076 times
1973 RD350
2014 Suzuki DT1000
1979 RD400F Daytona Special
1984 RZ350
2014 Suzuki DT1000
1979 RD400F Daytona Special
1984 RZ350
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Re: RD350 V's RD400 Cylinder Heads
The guys at the 2 stroke forum should make quick work of your conundrum. It is mostly RD 350 peeps.
Check them here:
http://www.2strokeworld.com/forum/index.php" onclick="window.open(this.href);return false;
Check them here:
http://www.2strokeworld.com/forum/index.php" onclick="window.open(this.href);return false;
Re: RD350 V's RD400 Cylinder Heads
HI thanks Evensje and even_calgary.
The RD400 heads have 3 long fins on the outside edge. Mine only have two long fins. So its all indicating they are 350 heads as the casting numbers arn't A1A, but they just have long reach spark plugs. I'll ask on the 2 stroke forum.
cheers
The RD400 heads have 3 long fins on the outside edge. Mine only have two long fins. So its all indicating they are 350 heads as the casting numbers arn't A1A, but they just have long reach spark plugs. I'll ask on the 2 stroke forum.
cheers