Forum

[Andy C]

The base "recipe" may be very similar but the additives make a huge difference.

[Presto]

I don't know the chemistry behind fuels but my experience is that my bikes all run better (start easier and respond more cleanly) with the higher octane fuels. And all seem to run better with fuel from major suppliers (BP, SHELL, TOTAL, etc). Maybe that's because I want to belive they do!
It's reported (in a very reliable trade source) that a number of major UK suppiers do not use ethanol in the higher octane fuels.

[Beezabryan]

An unmolested Bullet with its lowly compression will run on anything & I find no advantage fiscal or otherwise by using anything other than standard unleaded. Only once did I notice poor performance and that was 5 or 6 years ago when we filled up at a Total place. My riding buddy noticed the same thing, next refuelling with Texaco (I think) got the M21 & the Bullet back to normal.

[apparently lucky eddie]

Back in the 70's fuel shortage I ran the bike and a cortina on a petrol/parafin mix. Sure they ran ok (if you ignored the knocking!) but thats not the same as running as well as they could is it. Same with the cheapo petrol, yeah it works. But better petrol works better for me. Apparently unlucky eddie has to pay for expensive petrol

[Chris [Stockport]]

I have been experimenting with this for a while and found the more expensive / non supermarket ones feel better. However, next chance I have, a friend is going to fill it up for me and only after several miles will tell me what I got. Will be interesting to know if the situation is in my head or in the engine. Anyone else tried this?

The original idea came from my sister filling whisky glasses up for me, my father and my brother-in-law to see if we knew what it was, from a variety of bottles. We had fun experimenting but I can't remember the results.

Regards to all, Chris

[simon]

The fuel down here supposedly all comes out of the same tap before the anti knock is added to make it suitable for the various different recipients. My Duc runs fine on plain old 91 with no pinking or fuss but the bitza with a similar compression but a slightly cruder auto advance ( only very slightly I might add) prefers 95 or 98 depending on what it available as it will pink ( or ping as our aussie cousins say) when hot. I put it down to the different abilities of the two machines to shed heat. The Duc with ally barrel and steel liners cools in minutes but the bullet is much slower to cool. This makes it a better round town short hop machine but clearly the Duc has it for cruising. The extra 500 cc and 40 to 50 bhp help too. For a short time when tuning the Ducati I ran it on aviation gas which has lots of health giving tetra ethel lead in it but this was clearly going to price me off the road. It was a at more forgiving fuel though and whilst the plugs would eventually lead up (given time) they didn't do the strange thing that I've found with the unleaded stuff which if run too rich is to fail permanently due to incredibly conductive carbon. Even with. The most scrupulous clean they still showed as too low resistance on the megger and would if they worked at all fail under load. The thing that really demonstrates what a weird cocktail modern fuel is is the foul mess it leaves if you have a seeping cap or a leaking fuel tap. The varnish like residue is phenomenal and way more than anything the old stuff used to leave.

[Norm]

Simon,
you're on the money with a tad rich killing plugs and they won't clean up. Not sure if the old blast cabinet plug cleaning machine would fix them but the biggest problem would be finding an old spark plug cleaning machine. I haven't seen one in 40 years

[Grumpy]

Chris [Stockport] read my post above. Yes I have tried and yes I have the figures to proove for my diesel car I get the equivalent of 10% better miles per pound. As as I do over 550 miles per week it adds up to a significant saving.

Also worth noting is branded fuels have better lubricity and cleaning properties.

Try the Honest John website. He's also a great beleiver in quality fuels.

[apparently lucky eddie]

91 octane in a Duke Simon? Like you I used to run my 900ss on 100 octane (5*), it just would n't run on anything less with 11.5 - 1 comp. ratio. I used to fill up at Biggin Hill when I filled up the Cheatah and it used to go like the brown stuff off of a shovel! At a price. I seem to recall it was about a third more expensive than ordinary 4*.

[Les H]

Norm mentions a spark plug cleaner...One foot of copper tube...squash one end flat or bend over to seal.....1/4 full of bone dry sharp sand.....spark plug in the other end.....shake the tube up and down vigorously for a few minutes....remove plug.....blow out remaining grit.....worth a try maybe!