LCGB Forums

Hi,

Tomorrow I plan to install my crank and magneto etc.

What's the best method of sealing the gaskets.. grease or sealant. Anyone had a lot of experience and good results with a specific product?.

I'm using a decent halite washer and I'll also be doing the mag, barrel and head.

Any advice is greatly received.

I use loctite copper silicone one evrrything. Just a thin smear. I think stickies book suggests gresson on the mag gasket but I've found that this area is bad for leaks.

Grease on the chain case seems to be fine as it helps save the gasket if you have to remove on the road side.

Grease on chain case gasket, mag flange gasket and halite seal. Wellseal on head. I have been using 1103 neo and standard silicone on everything else but have just discovered Reinisol (sorry can’t remember propper spelling) seems good stuff and resistant to oil and fuel and only about £5 a tube off eBay.

I use Stag Wellseal on gasket faces... never get a leak

Clear silicone under the halite gasket and mag housing
Wellstag for head n base gasket

Depends if you would ever want to be doing a serious strip/repair on a longer run (?) If you use a sealant then once it is on, it becomes difficult to strip it clean all of the sealant off and then rebuild. However, a decent sealant will improve sealing/avoiding air leaks.

If you use a thin smear of the grease then you allow the gasket to float, seat and seal in the manner that it was designed to. Whilst it will seal correctly if faces are in good condition, it will not seal as well as sealant would if faces are rough or damaged. The big benefit of grease though is that you have a pretty good chance of doing a rally strip and rebuild without having all of the old sealant mess to deal with, and it is quite likely that the gasket will remain in tact and be ok to reuse... can be a life-saver if needing to do a rally rebuild without a spare gasket.

Pros and cons for both.

Adam

Thanks for all the advice chaps, much appreciated. Crank, barrel and head all fitted. I'll run a leak test on it tomorrow if I have the components knocking about to make one. Hopefully it's a good result.

If gaskets are to be used, then grease is good in every area except where any extreme heat is to be encountered.

My advice is to eliminate head gaskets entirely, which is far more achievable with the availability of metal cylinder base packing instead of gaskets. Previously, & occasionally even now, I have to make my own, but they are reusable & not compressible like gasket material. They also act as a template for port matching. Consequently, ‘run of the mill’ silicone sealant is fine there. Similarly, if ever I have to pack out the magneto housing (I had some alloy packer’s laser cut) the bathroom silicone is good. Never, ever the blue snot called Hylomar….

The exhaust gasket can be eliminated entirely rather than use those cr@ppy folded metal/asbestos items, though SOLID copper gaskets are, as above, a good template. If a solid copper gasket (Scooter Restorations sell them) then the Loctite 5920 Copper Silicone Sealant stands up to the heat & the oil of a two-stroke engine.

As for the cylinder head (with no gasket!) the same Loctite 5920 is my new favourite rather than other Loctite such as Bearing Fit or Threebond.

^... sorry, WT1 has just made me realise that I should have specified grease on paper gaskets too, not head gasket. However, like WT1 I would also look to lose the head gasket all together.

Adam

Thanks for the info guys, I ended up using Hondabond HT on all but the halite washer (used grease there). I'll see how the hondabond stands up to it. It's supposed to be effective to 600°f and good for cylinder heads.
Fingers crossed it will do the job. If not I'll try removing the head gasket altogether as suggested.