Hello fella's,

Does anyone recommend using stainless steel valve seat inserts for street use with "unleaded (cats piss) fuel"???

Is it worth fitting stainless steel valves to cope with todays fuel (gas).

Im currently restoring a 71' T120R and would like some advice.

Cheers.

Your head will have high density cast iron inserts as standard and they are now 36 years old...proper case hardening..I doubt that a nuclear isotope could damage those..Unless you have pocketing on the valves and they need recutting or actually replacing due to damage, then save your money...maybe get a belt drive for the primary and a 7 plate clutch?

Completely (well almost) agree with Bonnietiler. Don't think the seats are made from cast Iron but the theory is GOOD. Unless they are pocketed JUST RUN IT :hammer:
Use chrome stem valves and Phos bronze guides, NO OIL SEALS. You can put an 'O' ring on the valve stem AND machine the top of the guide at 45 degrees for half the thickness. This will allow some oil to lube the valve stem but when it is fully open, seal off the top so that the vacuum does not pull any more oil into the combustion chamber.
The machining helps stop oil build up on top of the guide.

I have not had good luck with hard chrome stem valves. I only use Kibblewhite Black Diamond valves and Ampco 45 high nickel content guides from MAP for street bikes. The combination is bulletproof when set up properly..with the correct tolerance. If your seats are pocketed, then you may be able to salvage the situation with .060" oversize valves from Kibblewhite. No seals or guide machining needed. The meager oil squirt from the rocker arms falls on the valve spring top retainer and doesn't flood the top of the guide.
The stock seats as fitted to all of the alloy heads are very hard and capable. I would only change them if the seats are seriously pocketed. The way to tell that is to pack the springs to the recommended length. If you need more than .100" shims with new stock springs, you need new seats or oversize valves.

[ This message was edited by: Mecchanica on 2007-02-26 06:34 ]

__________________
Triumph old, Triumph new, any Triumph will do.

No answers here. I put the 59 top end back on 'as found' just to see how the bike handled.I just lapped the valves a bit. It runs too good, but I do not know what the parts used back then were made of. What does anyone think will happen with those old parts and crummy fuel? I think they will outlast me. I've always got an eye out for an nine bolter. Someone told me that the plugs using todays fuel will always look sooty. Does anyone get a clean looking burn today?

Yes, Red. Infact they burn cleaner with lead free! If you have sooty plugs, check the plug grade and your carb settings.
Roy.

Well, I was told that Triumph/BSA had always used high density cast iron valve seats in their aluminium heads which was standard practise so to use throughout the motorcycle industry..Mind you I'm only repeating what a Triumph expert told me.It was Doug Hele who told me..I had a little chat with him in my journalistic capacity at the Bonneville Celebration, You must have been there Roy?..My money is on him though I must say.

[ This message was edited by: bonnietiler on 2007-02-27 02:45 ]

The only SERIOUS problem in the use of unleaded fuel in a Motorcycle is the fuel constituents. In order for the product to be usable in the engine after Lead has been removed the aromatic 'Benzine' has been introduced this is a highly toxic carcinogen and running a machine in a closed environment for instance is highly dangerous, doing the same on high octane unleaded potentially lethal with a far greater risk than you might imagine. A Catalytic Converter removes this harmful chemical from the exhaust and renders it relatively safe.
Cheers
BonnieT

[ This message was edited by: bonnietiler on 2007-02-27 02:42 ]

Benzene is a big no no here in the US, the EPA won't allow it. I suspect that is the case in the UK too. Generally, the additives in unleaded are metallo-phosphates and are more volatile at the temps that the internal parts reach, so don't form deposits. Most deposits will come from the oil. Synthetic oils from fewer deposits, as they are more chemically and thermally stable.
My plugs ran cleaner with the advent of unleaded.

Oh, the seats in alloy heads aren't cast iron, but austenitic steel.

[ This message was edited by: Mecchanica on 2007-02-27 15:48 ]

__________________
Triumph old, Triumph new, any Triumph will do.

Certainly that is the case today and even silicon steel inserts in some cases but not always the case in the 60's and early 70's. I think the Cbx 1000 Honda used another variant, Sintered Iron valve seats, indeed these are favoured by alot of cylinder head refurbishers in the UK .Some cars and other older cast iron headed vehicles often had the seats cut directly into the head, Triumph straight six for instance and the Austin Healey 3000. The use of cast iron inserts in Triumph/BSA machines was often used on motorcycle heads as that was all that was required, why bother with anything harder when the lead in the fuel did the job for you? It was a cheap product and easy to manufacture.
I'm unsure of US regulations on unleaded and am sure that you are quite right with ref. to the US but certainly Benzine is a constituent part of UK unleaded, although it must be said that the oil companies deny that quantities are at a higher level now than when Leaded fuel was widely used.
Incidentally, I lifted a head off my old BSA B25 last night, it rained and is cold, left the head on the bench and the seats are covered in a fine film of rust this AM, a sure sign that at least they aren't Stainless ....But then again it is a BSA I spose!
Cheers
BonnieT

[ This message was edited by: bonnietiler on 2007-02-27 17:40 ]