petrol additive

Singles, twins and fours.
john.whiting
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Postby john.whiting » Wed Feb 27, 2013 9:59 am

I dont worry about singles or iron head twins,but alloy heads are a costly item to insert,so I think if I had a Sq4 ,I would use a valve saver of some sort.Regards John.

nevhunter
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Postby nevhunter » Wed Feb 27, 2013 10:33 am

Do they work? We are only talking about the exhausts. Nev

robin.parker
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Postby robin.parker » Wed Feb 27, 2013 1:15 pm

My old airhead BMW R100RS did not like modern petrol at all, pinked like a peal of bells and overheated if I ran it a bit retarded (they were designed for proper 4 star). I resorted to Castrol "Valvemaster Plus" which cured the problem as it contains an Octane Booster and in about 25,000 miles of using it only had to adjust the valve clearances once, so there was no recession. Because you use such a tiny amount per tankful, it worked out cheap!
Robin.

nevhunter
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Postby nevhunter » Wed Feb 27, 2013 10:22 pm

Yes I've ridden an R100RS and can believe they would need good fuel. Castrol are a reputable brand, but how would you knwo about some of the other? Ordinary oils lower the octane of petrol but GOOd racing grade two stroke doesn't and also outboard oils . Tiny bit only needed, particularly on exposed valve gear motors and total loss systems, (early ones.) Nev

john.whiting
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Postby john.whiting » Thu Feb 28, 2013 10:40 am

The vintage car clubs in England paid for lab testing on additives,only four worked,all marketed by major oil co s.The results with brand names were on their website at one time.Regards John.

nevhunter
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Postby nevhunter » Fri Mar 01, 2013 12:54 am

That's interesting. No Boolium and foolium added. Nev

Simon.Gardiner
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Postby Simon.Gardiner » Sun Mar 03, 2013 11:53 pm

My R100RT BM suffers from valve seat recession even after fitting 'unleaded conversion' valve seats. (Additives like Valvemaster Plus make no difference). Didn't have any problems at all when it was running 4-star. My theory is that these days no-one apart from me actually rides one regularly for any length of time above 70mph. (Not in this country obviously :-) )
When unleaded first came in I was riding a VH with the 52-53 cylinder head. I tried it with unleaded as an experiment and had massive valve seat recession. However most people claim no problem with unleaded and iron cylinder heads (although it might depend on use - the same VH, now fitted with an alloy head, currently only does a few hundred miles a year and even if it was suffering valve seat recession I doubt if I'd notice it.)
The British car industry experimented with different grades of cast iron in engines. I think later A-sries Leyland engines use much a much softer grade than earlier ones and consequently later cylinder heads suffer more from valve seat recession with unleaded. I guess it's possible that Ariels followed the same route and the last of the cast-iron VH (and NH) heads might be made of a softer grade material than earlier ones, which might explain why mine wouldn't run on unleaded.
'55 Huntmaster, '56 VH, ' 51 VH, '80 R100RT, '00 Sprint ST (but all those Ariel parts can only make one running bike...)

nevhunter
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Postby nevhunter » Mon Mar 04, 2013 2:49 am

There are some extremely hard seats available in australia and they have reduced expansion rates to what used to be available. Some cast iron inserts will actually shrink once heated by hard use and come loose. Plenty of vehicles run on gas here which is very hard on seat wear. Inconel valve heads are sometimes used and you can weld the valve heads up and machine it afterwards, to get a better result. Nev

john.whiting
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Postby john.whiting » Mon Mar 04, 2013 10:13 am

Inconel and Nimonic 90 are gas turbine blade alloys.BSA Gold Star exhausts were Nimonic 90,and quite expensive.Lots of turbo diesel truck engines use these alloys.The valve seats that were used with unleaded were sintered iron with a solid lubricant,but thats years ago and I m out of date,so things may be different now.Most inserted seats in 50s alloy bike heads were soft cast iron,but Ive never bored out an Ariel,which are reputed to have a one piece cast in insert for both valves.My grandson was showing me his Husqvarna head which had broken both exhausts.Four titanium valves and four guides cost $1200,so classic stuff isnt that dear after all.Regards John.


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