I was never happy with the running of my Huntmaster (iron head A10 engine) despite using a fuel additive. I then found, fairly locally, a garage selling 4 star (leaded petrol) and was truly impressed with the change of the bike half a mile down the road, no more pinking, smoother running with more "get up and go". But............. at £1.99.9 a litre ouch!
I ran several tanks of 4 star and couldn't bear the thought of going back to unleaded, but cried each time I filled up. I did some research and came across "Millers Oil VSP VSPe Power Plus" around £20 to treat 500 litres of petrol. I also have a real bee in my bonnet about ethanol so have been using super unleaded which is often ethanol free, you need to check your local suppliers and this varies depending on the make and even your geographical area. It's easy enough to test for ethanol using a measured amount of water in a container (jar, test tube etc.) and adding petrol to this, shake well and firstly see if the fuel goes cloudy with suspended water in it. Then leave it to settle out and see if the water amount has increased, ethanol is suspended in petrol but mixes with the water making the water level increase. By the by, ethanol can be removed from petrol by this method.
A chance fill up of my GS 850 with BP Ultimate made a noticeable difference to her running, almost the same as the 4 star in the Ariel, has led me to now only buy from BP. I took the plunge and filled the Ariel with BP Ultimate, added the Millers and she's running as sweet as with the 4 star, it also cured the ache in my wallet.
I feel you have a problem beyond just the petrol you're using which hopefully you'll get to the bottom of. But ethanol petrol is a destroyer of classic vehicles and needs to be avoided at all costs, I'm very happy at having found a combination of fuel and additive which really works for my bikes.
Millers claim this additive (they do several) is also a protection against ethanol as well as an octane booster and lead replacement, I still prefer to go belt and braces and buy ethanol free petrol in the first place.
Colin
