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[Wheaters]

But the question was about fuel, presumably with standard timing settings

My 350 Electra doesn’t pink on “standard” unleaded and it seems to have a similar CR as a Redditch one. But it DOES seem to run better on “Super”. So does my 1991 CB750, again equipped with TCI ignition and carburettors.

I thought it was time to change the spark plug, due to the bike tending to cough a bit when idling, despite taking a lot of care with the idle settings. I treated the bike to an expensive Iridium type, just as an experiment. It’s cured the coughing and it seems to pull much better now, especially mid range.

[dalgrae]

Hi its my understanding that any super grade fuel will only contain 5 o/o ethanol up to 2026 whilst ordinary lower octain will have 10 o/o in it now, so I have always run all my classic bikes and the car on super .I also add a Millers additive as well (others available) to combat the 5 o/o ethanol.I have done this for years

Regards. Colin

[Duke of Wybourne.]

Something I learned regarding Enfields. Don't overthink, or you'll create a problem that isn't there.

[Rattlebattle]

What dalgrae says. I run all my vehicles on super unleaded, not for the higher octane ( not needed) but because of the ethanol content, which has a different AFR to petrol, so the more ethanol the more likely the fuelling will need adjusting.

[Cranky]

You do understand that high octane is not highly combustible --it is the other way round.

Over 10.5 will need 101 octane. Remember the rover 2000 TC-? -that was a 10.5:1 ratio and needed 101 octane unavailable to day.

As the compression was so high the fuel would ignite before ignition and caused --pre detonation, not good. I remember the 2000 TC at initial static at 10 degrees BTC and idle of 1000 RPM.

If you doped it a bit you could reach the compression before fuel ignited.

Doping fuel was common on racing engines, lead was used which is now banned.

SO--- a bit of diesel is what I use.

I also use cooking oil. All my bikes have a splash of cooking oil. Whats that smell Ha ha. who's having a BBQ.

Remember Redex upper cylinder lubricant --god im old.

[valentind82]

If it starts pinking, you either need to up the octane, reduce the compression or retard the timing. If it doesn't pink, carry-on.

There is a certain random factor with ignition timing on bullets anyway after it's gone through two idler gears and a distributor gear Stockage Mobile. What you measure isn't what you're getting unless you are strobing it.

You are right, we must give ourselves the means to do what we want.

[Wheaters]

I think it’s wrong to over generalise when it comes to engine settings. My four cylinder, 850cc trials car engine has a CR of over 12:1. The compression pressures were 225 psi (a 500 Bullet is far, far less). It ran well enough on super unleaded but the timing was non standard. Logic says retarded ignition would be needed but in fact it ran best when the “static” setting was advanced from the normal 10 BTDC to as far as 17 BTDC.

It’s still possible to find lead based additives. Also, AVGAS 100LL “Low Lead” still contains a significant amount of tetraethyl lead additive, about five times as much as Four star petrol did. It’s quite legal, only not for road use. I used it off road diluted one gallon in four. My 850 loved it, however one tank full would turn the inside of the tailpipe from black to grey.

[dalgrae]

Hi Millers VSPE combats ethanol,is a lead replacement and octane booster and is endorsed by the FBHVC.

[Cranky]

I strobed my 500 EFI carb converted ign timing today. I had made a visual of the mark to be expected through the plug hole on the timing case. You need to be ready and quick because even on side stand the amount of oil mist will contaminate vision either with or without glasses in no more than 5 seconds.

However i was able to see that I was about 7 BTDC---Im happy with that --it runs well. I have already cut the tab back 3mm yesterday. Its runs well so ille leave it. It pulls up the local Buddah hill as fast as it did with EFI so job done .

I am now on E20 and cooking oil,--and a splash of diesel shaken not stired. My 350 iron loved it in Malaysia.

Im talking about 10%. Smells great. like some one has been varnishing something.

[Rattlebattle]

Whaddya mean remember redeem upper cylinder lubricant? I still use it (The old stuff, I mean, not the modern pc/climate change/gender realignment compliant one, that doesn't work.....