fuel

E5  is the best availiable fuel at present . Some vendors may still supply E0  but it will be marked E5 anyway. Avoid supermarket fuels .  Isle of Man fuel was E0  last time i checked. E5 will slowly damage fibreglass tanks . run carb empty before stopping engine, ensures fresher fuel is availiable for starting . If a tank liner is fitted ,it may fail and clog carb and foul spark plugs. Check its not flaking or sticky. Fuel pipes and tap seals are vulnerable ,carry spares?.

E5 won't harm the engine, it should be fine. The problem only comes when you leave the fuel in over winter and it picks up water, and that causes corrosion. 

BP 97 octane was still ethanol free in the middle England area, despite the E5 labels, until the end of summer 2024 when I found it had 4% ethanol. Recently I tested it again and it has the same ethanol content. I think BP was the last supply of ethanol free petrol and I doubt any other forecourt source exists. 

As a matter of theoretical interest: literature declares that polyester resins (i.e. the resin typically used in GRP materials) is actually resistant to ethanol.  However, in one of my Phil Irving books he writes that 'dope' fuels containing petrol and eternal or methanol normally also contain acetone which improves how the alcohols mix properly with petrol.
Therefore my guess is that our problems are caused not by ethanol, but by the acetone additive.  It is no consolation of course...but probably explains why vodka isn't a useful paint stripper.

... and have long taken the view that ethanol isn't the problem but some of the other additives eg benzine (and maybe acetone?) may well be. I've mentioned before that Cleveland Discol which contained up to 20% ethanol (and no lead) was viewed as a premium fuel in the late 50s and early 60s, and bikes like Roger's thrived on it.

 I was talking to an ESso garage operator and asked if i could look at his spec sheets ,he passed over a thick  ring binder . looking through the information on each of the products it was clear that there were many different components to the fuel . most of which i had never heard of .  Its a proper witches brew of highly unhealthy compounds , and my memory tells me that at some time in the last few years the government gave an almost free hand to the industry.  The fuel supply to approx  90 % of the retailers now comes from one source ,pretty much a monopoly, and  owned by an Asian family i believe.

I'd agree with most of what you say, Robert - apart from the fact that our problems originate with government interference with chemistry they don't understand and don't care about.  (They mostly have Economics or PPE degrees and no hobbies.)  They'll declare "only a small percentage of users will have problems" as if it doesn't matter - when 3% of vehicles is still over a million vehicles.

Even so - I've not had problems with E5.  But I do try and drain carburettors down if I'm likely not to use a machine for a while.  The reason I try to avoid E10 is that I think it's an even better paint stripper.

Easily is the tricky bit. If you can plan your route so that you are passing private airfields at fill-up time, pop in and see if they will sell you avgas. I have only tried a couple, but they have always obliged thus far.

Avgas is usually 100 octane, contains no ethanol (I understand it is not allowed to, which is telling) whilst addressing your other concern, as it contains a small amount of lead. Even every other fill-up would help, wouldn't it?

I trust you are over starting issues Roger. The engine was rebuilt about six months before you bought it. It had been run in on E5 and had occasional to be filled with E10 on a long range out of district run. It is not highly tuned just rebuilt after long service as a ride to work machine and stood idle for many a year.  Ethanol has a higher octane value than straight petrol so performance will not be affected.

Biggest issues with ethanol is its hygroscopic property attracting water into the fuel system which can create emulsions which will enter galleries and solidify.  So the answer is use the fuel, top up tank at the end of each run to reduce the humid air in the tank and drain the carbs on your run in.

You won't have issues with that machine.
Best wishes
Jon

Use E5, and E10 if no E5 available. Your engine has hard valve seats (alloy head) so it can cope with this. Shut the fuel tap when your a mile from home and let the engine run out of fuel before putting the bike away (empty the carb/s)  

Decades ago i built and raced a Formula 2 sidecar outfit powered by a Yamaha TZ350G engine.
the first meeting or two we used Avgas (blue in colour and designated 100 Low Lead) Not cheap.
I then started to brew my own fuel using petrol/acetone in the ratio of 7 to 1 (three and a half gallons of four star to half a gallon of acetone) This was easy to do with a four gallon Jerry can. put half gallon of acetone in the empty Jerry can and on the way to the meeting fill up with four star. The engine went very well, same power as avgas and no detonation, plus it didn't colour the fuel. You could smell the acetone in the fuel though. Recon we had something like 105/110 octane.   

You can use E5, E10, E0 etc, but remember that where you are toping up the E5 may have sat in the forecourt tanks for months - I doubt they sell it quickly enough. 

The point about emptying the carb before laying up is particularly relevant to premixed 2 strokes (as I have found with my Bantam).