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unleaded fuel in a65
April 1, 2013
8:43 pm
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BASIL
Club Member 874 Hamstreet,Ashford. Kent Area Rep.
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April 2, 2013
9:19 am
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Sparky
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April 3, 2013
10:03 am
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Cornish Rooster
Saltash Cornwall
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Don't get over concerned about running an older engine on modern fuels especially with regards to valve seat recession, ok if you do really high mileages and at high speed on say Motorways etc then it could be an issue but even then maybe not.

I have been running my older four-strokes on modern fuels without any problems and my Moto Guzzi Single has been used on modern fuels for around 13 years now and has not suffered any valve seat problems judging by my infrequent valve clearance checks. This bike has done some long runs as well including covering 270 miles or so in about six hours, my 250 Starfire has also covered around 275 miles in a day and again no noticeable valve seat wear and both these bikes do NOT have modern valves and seats. 

The main issue seems to be that these modern fuels make the combustion hotter and the fuel has less calorific value (energy) so with a higher performance engine some carburation changes may be required. A good start is to use the "super" grades on these engines and dependant on where you are in the country it may or may not include an ethanol content.

My single carb A65 Thunderbolt was pinking quite badly under load under certain conditions, such as pulling up a hill in top gear, to overcome this I fitted a "3" slide to replace the 3 1/2 original spec (slightly less air) and went up 10% or so on the main jet size going from the original spec 230 to a 250, and since then the pinking has gone. I fact I think the carburation must be just about spot on now, it pulls through the throttle range very well. These single carb A65's have some real grunt and the way it picks up in top gear from say 50 mph to 70 mph is very impressive even by modern bike standards, plus on a run doing between 50 and 70 mph it will do around 70 mpg ! It will also quite happily sit at 70 mph all day, a very under rated engine these A65's and surprisingly smooth if put together well, though mine does have a balanced crankshaft and pistons.

By all means use an additive if it makes you feel better, it can't do any harm, I still have some in my garage though I haven't actually used any for years.

Phil 

BSA Bantam D1 "150" in use regularly often as general purpose transport, quite a few other bikes as well. Cornwall Area Rep. 

April 4, 2013
3:28 pm
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Scotnormbsa
Club Member 599 Blackridge West Lothian Scotland
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April 27, 2013
10:17 am
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Cornish Rooster
Saltash Cornwall
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BSA Bantam D1 "150" in use regularly often as general purpose transport, quite a few other bikes as well. Cornwall Area Rep. 

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