Road Toad - DOUBLE head gaskets?

[spudman]

I pulled the head off my '75 model 99 Road Toad to give it a fresh paint job along with the case covers and when I did...I noticed that there were TWO (2) thin metal head gaskets in place. I know this isn't normal, but I was wondering if anyone could shed any light on why there were two of them. I bought the bike a few weeks ago and it runs great! It only has a little over 1000 miles on it and according to the previous owner, the engine has never been touched. I did notice one other thing though. On the actual machined, non-painted mating portion of the cylinder (the shiny part where the gasket goes and the head matches up to it) there are two markings stamped into the surface. One is a small triangle with an "H" in the middle...so I know what that is. Right next to that though is a "+2" stamped into the surface. I'm wondering just exactly what that signifies. Is it to indicate that the cylinder has been bored to a larger size? Could this be the reason somehow for the extra head gasket? I'm not really too up on my internal combustion technology, so any help is greatly appreciated! Thanks.

[Dale]

The +2 stamp was used for factory sizing during assembly. It does not mean anything significant once it left the factory.

The double gasket could have been to decrease compression or to gain head clearance or perhaps someone had trouble getting a good seal. It could have been done by a competent mechanic or someone who did not know what they were doing. Sorry, that doesn't answer your question but hopefully gives you some ideas.

[spudman]

Thanks Dale. I guess now I'm wondering if I should put it back together the way it came apart (using two gaskets), seeing as it was running fine. You don't think there's any damage I could do by just using the normal "1 gasket" method, do you?

[Dale]

At the risk of being a little dark cloud... some caution is warranted here. I don't know what experience level you have or what tools you have. First, be careful re-using a head gasket as it may not provide a tight seal.

If the second gasket was there for a reason, one can only speculate what that reason was. And yes, damage could result from changing it although I think that is unlikely.

When the head is installed, you can make sure that no piston to head contact is being made. You can also measure the squish band (Google that).

A leakdown test and a compression test would be desired too.

[Bill2001]

Good cautions, Dale. I would have assumed that the head gasket was doubled to reduce CR so that Regular gas could bed used. Did that on the BMW for many years til I dual-plugged it. But on these old bikes you need to learn "the story behind the story".

[spudman]

Thank you very much for the tips Dale. I'll be using a new gasket, as I ordered the entire gasket kit for the bike. I have a friend that is very knowledgeable with the tests you mentioned, so I'll get some help from him when I reassemble everything. While I've never heard of the squish band, I found several good You Tube videos that both explain it and show how to measure it. Thank you again...I appreciate the help!