leaking head gaskets

e3steve · Post by **e3steve** » Sun Dec 07, 2008 5:48 am

There's a forum poster here with copper head gaskets on eBay; I'll post the link when I find it. I'd say that proper Honda NOS head gaskets are the only way to go, but this guy has used his coppers with success. LM's comments appreciated here.

Copper head gaskets were used for decades on iron/iron, alu/iron & alu/alu motors until cheaper gasket production methods came to the forefront.

e3steve · Post by **e3steve** » Mon Dec 08, 2008 11:03 am

Quote from Britman:

I have used copper head gaskets on couple of old British Thumpers with good results. Just throwing out for opinions.
http://cgi.ebay.com/ebaymotors/HONDA-30 ... enameZWD1V

305 nutt · Post by **305 nutt** » Sun Dec 21, 2008 10:13 pm

Well, I got the cl77 running last week and have run it for over an hour and it is leak free. No doubt in my mind the genuine nos gaskets are the only way to go. Thanks for all the help. Nutt

rbaselt · Post by **rbaselt** » Mon Dec 22, 2008 1:41 pm

It seems to me that if the O-rings are doing their job that the condition of the head gasket is of little consequence. The oil has to go past the O-rings before it ever comes into contact with the head gasket. The O-rings are supposed to have a thickness of 1.6mm, but the NOS ones I have measured lately are only 1.3mm. Therefore, if your replacement head gasket is just slightly thicker than normal, the O-rings will allow oil to pass. A possible cure is to do as Bill Silver recommends and use sealant around the O-rings, or to find a thicker high-temp O-ring. Also check the thickness of your head gasket. Subtract from that the thickness of your O-ring less the depth of the O-ring recess, and you will know if there is any excess height to the O-ring once everything is in place (should have 0.2-0.3mm of O-ring standing proud). --Randall

305 nutt · Post by **305 nutt** » Mon Dec 22, 2008 6:17 pm

Thats interesting, I'll check the thickness of the o-rings. I ordered them through honda, but I didn't measure them. The aftermarket headgasket I took off was definately thinner than the original and it had porosity holes punched in the top and bottom of gasket, not all the way through, but just the way the material was made. When it was on the bike, you could watch it leak right in the center of the head. I assumed it was oil being slung off the cam chain. I did coat the orings and the insides of the oring surface of the gasket both times and it is leak free with the honda gasket. Thanks for the insight on the orings though, I have 2 more motors to tear apart and replace those crappy gaskets yet. I restored a dream and sold it to a guy last summer and he calls the other day and said it started leaking oil. I had a gutt feeling I knew what it was and sure enough its leaking in the center like the other 2 were. Oh well, lesson learned (an expensive one at that)!! nutt

rbaselt · Post by **rbaselt** » Mon Dec 22, 2008 7:21 pm

If the leak is at the center of the head, it must be from the cam chain area. One of your earlier posts made it sound like it was leaking at the two outer edges. So much for aftermarket head gaskets. One of the suppliers, possibly Ohio Cycle, sells a replica head gasket that is pretty good.
Randall

advantagecycle · Post by **advantagecycle** » Wed Jan 07, 2009 6:26 pm

Yep, I noticed the aftermarket kit I had bought had a thicker head gasket than the stock. I used a generous amount of 3bond on both the head and cylinder surfaces to ensure the o-rings sealed up.

Paul