Cylinder head o ringing

[4cyl h2]

Can anybody tell me some info on the cylinder sealing o ring mod?? I'm wanting to do this for my air cooled rd. Will they overheat and fail, can I use the ones designed for the banshee or would they be different. And what the spec for the trench. I've read up some but doent see info for the rd

[justind97]

You'd be better off using a copper headgasket and annealing it every time you take the head off.

[two-stroke-brit]

a guy on the Kawi triple forum has a H2 which he o-ringed the heads many years ago and highly recommends it.
there is a guide by "parker" that supplies the info needed to cut the groove.
generally its 3/4 of the o-ring thickness deep.
mark

[slinger]

I use them with the air cooled 250 350 and 400 engines

[bitzz]

Oring'ing a head is a viable method of sealing, air-cooled or water cooled. Copper gaskets are definitely easier.

Be aware you are changing the compression ratio and squish by removing the head gasket.
For RD400s I mill a 2mm wide, 2mm deep, 75mm OD trench. Most cut the head on a lathe, I made a fixture for my rotary table... don't ask.
I suggest you get the oring (nitrile or better) THEN decide on the dimensions of the trench.

... if you go to the trouble of oring'ing the head; Install locating pins at the same time.

[JanBros]

any 2-troke should be O-ringed (water and air), it's so much easier and you can open your engine anywhere/anytime as almost all the times the rings are re-usable.
O-rings can not be squeezed together, only deformed. therefore, the cross-section of the groove needs to be just a tiny bit bigger than the cross-section of the ring.
I always make the groove 20% less deep than the thinckness of the ring.

a 2mm ring has a cross section of 1x1xpi = 3.1415
so a 20% groove is 2x1.6 = 3.2mm²

and remember to use viton O-rings, they can handle the high temp's !

[4cyl h2]

Where would be a good place to get o rings

[South_Oz]

I bought mine off evilbay. Pack of 25 for not much.

Dave

[two-stroke-brit]

Where would be a good place to get o rings

mc master carr has a tremendous selection .

but may not ship to you depending on your secret location

[RuZty]

Most industrial supply houses also carry them, I got a bag of 50 locally for around $30.

[4cyl h2]

Ok so what size should I be looking for and how smooth do the cylinder deck and head have to be ?
It's no problem for me to lathe the cylinder top and cut the groove but I also need specs for the o ring groove and don't know how smooth I can cut them

[two-stroke-brit]

Ok so what size should I be looking for and how smooth do the cylinder deck and head have to be ?
It's no problem for me to lathe the cylinder top and cut the groove but I also need specs for the o ring groove and don't know how smooth I can cut them

i would think if the copper gasket is removed ,the chamber would need to be re profiled as well to get proper squish and compression.

[4cyl h2]

Does it matter if the groove is put in the head or the top of the sleeve?

[MK]

I did both and prefer the cylinder.
If you cut the head, there's always a risk of the ring falling out of the groove during engine assembly ...

[two-stroke-brit]

I did both and prefer the cylinder.
If you cut the head, there's always a risk of the ring falling out of the groove during engine assembly ...

if you have the choice the cylinder is preferable as martin says