Ariel Owners Motorcycle Club

*combustion

GOOD two stroke oils these days don't produce carbon You only need a trace which will not affect the mixture much at all.. Hard seats are better but why fit them till your originals are too recessed?. Don't dress the seats in such a way that an insert has to be too large a diameter. Most seat damage is done by putting in new guides that are off centre requiring a lot of metal to be removed to get a new seat formed. You can open out the inlet port and use a bigger inlet sometimes if you want a bit more power and avoid fitting an insert which is something else to go wrong IF it's not done well. Nev

Thanks Nev
I appreciate the information, thank you

David

Tank sealers work.
Best of the sealers I have used is probably Por15.

Harder valve seats are only needed if you intend to go for very long high rev runs, like perhaps 80mph down the outside lane of a motorway all day, not likely I suspect! And exactly as Nev says, why worry until yours are recessed anyway. When unleaded first came in, many classic car and bike enthusiasts spent a fortune of valve seat replacements that were largely unnecessary. I had a protracted argument with a mate who was convinced he needed to replace the seats on his Triumph. I eventually persuaded him not to, and judging by the fact he's probably ridden his old bikes less than 1,000 miles in the last 30 years, I was right

I have to say, even going round London on a VH with the 52-53 head and using the so-called lead replacement stuff that was marketed when leaded petrol got banned you could almost hear the exhaust seat receding and the tappet clearance disappearing hour by hour.
(I specify that particular type of head because the iron seems to be very soft and its' possible that the factory was experimenting with a softer, cheaper material - in the same way that BL did with later 'A' series heads.)
My BM R100 is now on it's 3rd unleaded conversion - the first two still suffered from seat recession despite having so-called hard 'unleaded' valve seats fitted by very reputable specialists. They were OK as long as you didn't go above 55-60mph (half revs?) so I'd agree that you don't always need harder valve seats to run on unleaded but I'd put the use conditions rather lower down the scale...
(Apparently the quality control at BMW was rather iffy in the '70s and '80s, some factory valve seats were actually a lot harder than the spec - some were softer - so yes, in airhead BM-land it's always possible that someone honestly has an engine that's always been fine with unleaded even when used at 80mph on motorways day in and day out.)
(Gone off topic - not needing harder valve seats is a bit of a sore point in this house. )

SG

The HARDER ones stay in better. Soft inserts can shrink at high power (temps) and come loose and fall out doing a lot of damage. They lose their "interference" fit. I never use anything but the best quality. Vehicles running on LNG have a similar effect to using unleaded fuel with regard to valve seat wear. Nev

One of the best internal tank cleaning methods I have used and Sean used by other people is put 2-3 handfuls of small nuts and bolts and or hard stone gravel, put the cap on put some strong tape round it so it won't come off,wrap it up well in a duvet (best not to use the one of you and your wife's bed)tape it so it cannot unravel, and put it in your mate's electric concrete mixer for about 30/45 minutes, nearly forgot, put1/2 pint of Jizer or similar in the tank.