Thread: Removal of cylinder gasket after porting

I did it to my husqvarna 372, i cut a grove around the flat machined surface of the cylinder so when i put sealant on it that it would have a better chance of sealing it. I used my carbide bit to do so, I will post pics in a day or so of a few other jugs im doing for local friends to show what i mean. I've heard guys on here say they've done it to, any pics and advice would be greatly appreciated!

we need pictures!!!!!!!!!!!

this creates a sort of 'cast in place o-ring'?

i like the idea. though, there are some smaller saws that don't have enough real estate on the flange to accomodate it.

Originally Posted by volks-man

this creates a sort of 'cast in place o-ring'?

i like the idea. though, there are some smaller saws that don't have enough real estate on the flange to accomodate it.

very true and on my 372 space around where the transfers are was VERY limited lol i had to make sure i had a steady hand, the vice did the holding part

Not really necessary but it would not hurt if there is enough of a flat surface to make a groove and not break through the casting. There is actually very low pressures created in the crankcase of a chainsaw engine.
Pioneerguy600

I would not waste the time, it will not provided any better seal than a good metal/metal fit with a thin skim of fuel resistant silicone. Some jugs get weak in the bolt ears when turned down, though 372 is not that as bad as dolmars, solos and some of the stihls like the 361, just the same I would also avoid cutting away the extra metal to make such a groove.

Like Pioneerguy mentioned above on the husky jugs there is very little room around the transfers esp if the transfers have been worked over.

Hmm these are all great opinions, they all make enough sense and i like where this seems to be going. I thought the silicone would just fill in the small imperfections between the machined surfaces. I only cut the grove to increase the chances of it not leaking.

I'v pulled gaskets on many saws and never had a base leak on a simple metal to metal fit just with a skim of sealer. Actually often have done the heads of a two piece head with just a metal to metal fit and that has held fine at closer to 1000 psi.

If you are worried about a leak use Yamabond, Hondabond or one of the other anerobic high strength sealers. By how difficult they are to clean off they must hold well. It takes a good tap with a hammer to knock the jug loose once the bolts are out.

I would venture to say that you get a better seal without the groove. I believe you were probably thinking of it similiarly to an o-ring. The difference is that an o-ring will be compressed. You silicone will not be. A thick layer of silicone will blow out more easily than a than layer.

great advice, perhaps i was doing this extra little bit for nothing after all. its good to learn new things. Thanks to all!

You really need to be setting your squish before you port your cylinder. You'll have a lot more accurate idea of where your port timing numbers are if you set your squish where you want it first. Then you can decide which numbers are going to work best for the power band you want out of the saw.