Tech Forums > SOHC/4 Bikes
brandEn's leak free top end thread = Tips, Tricks and Suggestion encouraged
Niels Bull:
how do you view these pictures??
HondaMan:
--- Quote from: turkey4me on September 22, 2016, 03:46:13 AM ---No 8 O-rings on are listed as being 11 x 2.5mm. Can anyone confirm if 11mm is the inside or outside diameter? Buna or Viton?
--- End quote ---
Just one addition: all modern head gaskets are thicker than the OEM gasket upon with the 2.5 mm thickness was established. The modern gaskets are 1.0mm thick (some are even more) where the OEM version was 0.8mm thick, and you need to use an O-ring that is THICKER BY THAT AMOUNT. I use the Parker #01-111 that is listed as 2.62x10.77mm size, but is usually thicker than that, to seal the oil passages between the cylinders and head, AFTER having the cylinder top surface decked 0.010" during boring (which also ensures it is flat) - the head gets decked up to that amount, also.
I have a LOT of these O-rings: if you need a pair, I will send them to you for a donation to our website. PM me for details.
jnymdnyt:
Thank you so much for this very detailed post and thank you as well for everyone that contributed. You all just saved me a bunch of time doing research.
PeWe:
O-ring size: Usually inner diameter x cross section (thickness)
11 x 2.5 has outer diameter 16mm.
So when change to a thicker, inner dia must be smaller to not increase outer dia too much so it still fits. Here inside the gasket holes.
Same with oil feed o-rings. The inner dia can not be too small either so it block the oil feed when compressed.
Here just a few 0.1mm to compensate for thicker gasket.
I used 8 THICK o-rings with late CB750 head gasket and early cyl/head. I had to re-torque the head 3 times until it stopped compressing, nuts moved after 24 hours!!
I used thinner viton O-rings next time (changed head), something like Hondaman recommend. Re-torqued once after 24 hours was enough. (I tested once more)
ADW:
Here's my experience and suggestion(s) on my 350F from summer of 2019. Reference to gasket sets with taller O-rings and etc. included.
http://forums.sohc4.net/index.php/topic,179085.msg2077683.html#msg2077683
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version