Viton o-ring as head gasket?

[hayd3n]

k while i have the engine apart (x250) , and upsizing the headbolts,
i had the idea of machinging a groove in the head to fit a viton oring they are good for 400 degrees
,
it wouldn't be to hard for me to make a groove in the lathe with a 4 jaw chuck
but thinking as its air cooled it may be no good?

[Woodman]

I have grooved a few blocks and tapped copper wire into the groove and sealed the surfaces with Loctite 518. Works real good. Haven't done it on air cooled motors, only a couple of SB Chevys, a 308 and a 4 cyl Denco.

On my old IT175 I just lapped the head onto the barrel with valve paste and it sealed fine, and my benelli is also lapped in so can't see any issues with your motor.

[hayd3n]

I have grooved a few blocks and tapped copper wire into the groove and sealed the surfaces with Loctite 518. Works real good. Haven't done it on air cooled motors, only a couple of SB Chevys, a 308 and a 4 cyl Denco.

On my old IT175 I just lapped the head onto the barrel with valve paste and it sealed fine, and my benelli is also lapped in so can't see any issues with your motor.

interesting

[hayd3n]

no one else care to comment?

[Asher]

Make sure to add the thickness of your head gasket to the base gasket

[hayd3n]

Make sure to add the thickness of your head gasket to the base gasket

[scumdog]

I am pretty sure it was Isky that made the 'Groove-o-matic' (sounds disco eh!) for machining a groove in the top of the block, a copper wire O-ring was used.

Worked well with turbo'd motors.

The only one I knew of is no longer in the country....but it would be worth asking after one.

[FJRider]

no one else care to comment?

Do you have a reason NOT to use the factory head gasket ... ??? You already have one ...

[hayd3n]

Do you have a reason NOT to use the factory head gasket ... ??? You already have one ...

no i susessfully drilled out the holes in the old gasket,

+ i still need to order a exhaust gaskets and a valve cover gasket
the classic motorbike dude in nelson hasn't replied back with a price yet

[Woodman]

I am pretty sure it was Isky that made the 'Groove-o-matic' (sounds disco eh!) for machining a groove in the top of the block, a copper wire O-ring was used.

Worked well with turbo'd motors.

The only one I knew of is no longer in the country....but it would be worth asking after one.

The copper rings first used in the turbo'd motors were in conjunction with a head gasket so the copper wire would bite into the gasket just outside the bore binder. was a common mod on 2.0 Cortina motors when fitting hairdryers. Can be done on an overhead boring machine easy enough. Aaaaahhh those were the days.

[SS90]

no one else care to comment?

Bottom line is yes...... Viton Oring is perfect in this situation, many performance air cooled two strokes use Viton orings.

I am informed that over 400 deg Viton orings burn and produce a poison gas, how this is relevant I don't know.

[Ocean1]

Bottom line is yes...... Viton Oring is perfect in this situation, many performance air cooled two strokes use Viton orings.

I am informed that over 400 deg Viton orings burn and produce a poison gas, how this is relevant I don't know.

Probably a low liklihood of exposure for that application, very serious consequences if you get it wrong.

Viton: http://msds.dupont.com/msds/pdfs/EN/...35803ee796.pdf

Hydroflouric acid: http://www.chemistry.auckland.ac.nz/...DS%20Sheet.pdf

[Banditbandit]

On my old IT175 I just lapped the head onto the barrel with valve paste and it sealed fine, and my benelli is also lapped in so can't see any issues with your motor.

Yeah ... done that on a 2/ motor myself ... worked fine ...

[ac3_snow]

I have lapped the head/ barrell together on one bike, I lap'd each on a bit of glass for the first bit and then together. Also on my current engine a tf125 run a vitron o ring.
When the barrel was machined he did it right around the edge of the steel liner, that way he was only machining alloy made the job much easier. Get a o ring of the right size first, before you do the machining. I have used these guys http://www.sealimports.co.nz/contacts.html but I am sure there would be a similar outfit in dunedin somewhere.

[imdying]

Flat is a relative concept, and lapping things like that is a waste of time. An engineer will have it proper flat in no time though. Lapping shit just makes it lopsided and patchy, and glass is not flat.