MOPED ARMY

Oil helps it compress evenly, it will get somewhat wet during use and I think the basic idea is you soak it first so it's all soaked instead of unevenly wetting during use and potentially compressing more in those spots and enabling a leak.

People also use sealers, for some applications it's worth it, but honestly I mostly use sealers 1) where no paper gasket can go due to clearance, like many engine cases and 2) just to hold paper gaskets in place. it's a pain when the gasket falls and you punch a hole in it when putting in a bolt cuz it slid down and wasn't lined up right. If you glob it all up with silicone though the little bits can make unnecessary mess. I don't think silicone is "breaking down" paper gaskets as I've seen some places suggest, theres some mild acetic acid (vinegar) part of the curing usually (however those types of RTV are usually not good vs gas/oil) but that's not gonna hurt anyone. I think it's more that you just don't get any synergy - if it's a high pressure seal it's gonna leak out whichever is weaker, the paper or the silicone around it. so you don't benefit from both. (except holding it in place)

As for which RTV? doesn't seem to really matter. people have used everything and everyone' got their favorites and there are small differences and none significant. it's like asking what oil to use. some people say use the fanciest nicest most expensive, and someone else has probably run for 15 years with superglue and playdough

Anyway in your case, you can smear some JB or epoxy on the outer edge it'll give the gasket more space to seal and no chance of it hurting anyone. An easy way is clean it up, put your gasket down and put some wet JB there, compress it with the cylinder as you put it on and then you don't need to worry about poishing it flat. it's just there to back-up the seal. I'd also cut that case match a little away off the edges, though any lip in the match creates unwanted turbulence...

oh yea definitely! wasn't thinkabout that but if you ever wanna reuse, wet it. that's very true. even just getting old gaskets off is way easier. I definitely use grease a lot to hold stuff in place too. whatevers closer hah, usually i'm just using sealer to hold like a trans gasket cuz I just sealed the case with it or whatever and it's right there on the bench. grease is also nice cuz you don't spill oil everywhere when you inevitably knock it over

If you are going to use a sealant make sure it is anaerobic. Motoseal, yamabond, curril k2, etc. You can also build up the sealing surface with epoxy if your worried it won't seal.

thanks for the info dudes!

Going to go with the old faithful and oil the gasket and try a little grease this tkme to hold it in place/ make removal easier.

I’ll leak down test the motor before mounting it to the bike to make sure and if it fails I’ll try building the deck wider in the thin area with jb weld as suggested.

yea you've got a nice opportunity with JB there cuz it won't require much and it's not directly sealing anything, just providing backup in such a way it'd never potentially wind up ingested.

As for yamabond, hondabond, the anaerobic ones seal without air and ideally you don't have air in well sealing surfaces, but I don't think it matters which one you choose, they're all based on the same chemistry

Jbot what number Yamabond ?

I never thought of jb weld. My buddy that helped rebuild my motor mostly fixes landscaping equipment ie. Lawnmowers so he didn't care much about air leaks. He just put my cylinder head on a grinder to clean it. I might just jb weld my cylinder head gasket to the cylinder head and wait for it to dry before attaching it to my cylinder. (edited)