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Myles Raymond
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Hello... And thanks in advance for any advice anyone can offer me on my question

I bought a 1970 BSA Lightning last year and I recently read on another forum about using a lead fuel additive for older British bikes. I have a 4-gallon tank and have been putting premium unleaded in it before now. Can someone suggest a brand they think is effective? And how much would I use for a large gas tank?

Thanks!

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Don’t use any. It’s a con.


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Originally Posted by triton thrasher
Don’t use any. It’s a con.

Plus 1,

But if you feel you must use something. Get yourself some octane improver or Tetraboost. But for a Beezer it’s really not required.


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68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (now rebuilt)
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Plus 1,

my understanding is that BSA's from that era already have hardened seats so there is no need for any lead replacement additive.

The only other point to consider is that modern petrol goes stale after a few months, so keep fresh especially if the bike is overwintered.


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Im not convinced it actually does anything but i use a small squirt of Moreys (sp) upper cylinder lube ...the stuff that dilutes 600/1.... there are plenty of varieties of that stuff....what it does do is make me feel better so i recon its worth it


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No signs of valve seat erosion on my 69 Thunderbolt after thousands of miles on California (and occasionally Nevada) gas. I don't see any need for additives.

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While we don't have leaded gas in British Columbia, we do have Chevron 94 which is labeled as no ethanol. I buy this fuel in a 2 gallon can for the lawn mower, chain saw and motorcycle spring startup as even if I keep some over the winter, the lawn mower is happy next spring. Usually I just add any leftovers into the car in the fall which gets me into using a new can next spring.

The only valve seat damage I have ever experienced is the pocketing of the seats by a local machine shop. I have never bothered with adding anything. We are so fortunate to have more than one fuel choice which claims it is ethanol free. There should be a law.......

Cheers, Wilf


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I use what's called recreational gas here in Michigan. 91 octane, no ethanol. Use it in the 71 BSA Lightning, 72 CB750 and in the 2000 XLH H-D. No problems.

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It's called 'clear premium' in the west.

Pick your state and it shows where it's available.

https://www.pure-gas.org/index.jsp


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throw in some 100LL Avgas. even 20% makes a difference. 100 "low lead" has about 4x the lead that the old leaded 87 octane had. its $5.50 a gallon where I am but it works. old bikes love leaded gas

and yeah, those additives are a joke

Last edited by Mitch; 08/25/20 8:05 am.
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Use high octane gas. No racing fuel unless it’s lead free. Lead salts bad. I use maxima booster. Works for me. Bikes start easy and idle smooth.

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Originally Posted by Mitch
throw in some 100LL Avgas. even 20% makes a difference. 100 "low lead" has about 4x the lead that the old leaded 87 octane had. its $5.50 a gallon where I am but it works. old bikes love leaded gas

and yeah, those additives are a joke

I run Avgas in all my machines. Cleanest plugs ever. No deposits. Avgas here right now in this valley is $4.25 to $4.95 self service. Avgas has a long shelf life and doesn't stink bad like pump gas.


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yep.... leaded gas is a different thing... the engine will run different.... like it was designed to actually. its hard to believe that there are people that have never used leaded fuel but then there has been no leaded auto fuel in the USA for almost 40 years

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I tried my Lightning on Leaded fuel and it preferred the Shell V-power unleaded. Not a bad thing as the few garages that were selling leaded fuel were also extremely expensive.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
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67’ D10 sportsman (undergoing restoration)
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In my Hornet I run 20% Trick 100 unleaded 80% 91 O. I put a tablespoon of Castrol R equivalent or a tablespoon of model airplane fuel. Just for the smell.

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The last few race meetings i attended i just used bp 98ron.unleaded.
I used to religiously run 30-50% leaded av gas with it but in all honesty
it made no difference to performance. Modern fuel is faster burning and
the lead was only an octane booster and valve seat lubricant. If the
replacement fuel is of a similar octane it will probably be better than
leaded avgas which is a relatively slow burning fuel.

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Originally Posted by NickL
The last few race meetings i attended i just used bp 98ron.unleaded.
I used to religiously run 30-50% leaded av gas with it but in all honesty
it made no difference to performance. Modern fuel is faster burning and
the lead was only an octane booster and valve seat lubricant. If the
replacement fuel is of a similar octane it will probably be better than
leaded avgas which is a relatively slow burning fuel.

Yes, pump gas goes "boom", whereas Avgas goes "booooooom".


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Leaded avgas formulated to run in engines that run at around 3000rpm.
If that's all your A65 does, sell it and get an M20.
Better to stick a drop of Toluene in standard pump fuel.

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Nicks spot on. Octane additives come in the form of Toluene, xylene and iso-octane (toluene and xylene blended are mentioned in the article below)

Read the following article


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68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (now rebuilt)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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Originally Posted by NickL
Leaded avgas formulated to run in engines that run at around 3000rpm.
If that's all your A65 does, sell it and get an M20.
Better to stick a drop of Toluene in standard pump fuel.

Say what you want about Avgas. I've been runnung it for decades in a multitude of engines including MC's, vintage Mini Cooper, VW sand rails, ATV's, WWII Hercules search light power plant, small utility engines, aircraft (obviously) and more with great success.

But it's likely not for you. Don't use it.


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Originally Posted by NickL
Leaded avgas formulated to run in engines that run at around 3000rpm.
If that's all your A65 does, sell it and get an M20.
Better to stick a drop of Toluene in standard pump fuel.


hey.

tetraethyllead is unobtainable without special dispensation from mount olympus.

but i can buy five gallons of toluene for US$64.

how well does that work for retarding detonation?

not talking valve seat recession


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You probably wouldn’t notice much difference in ignition timing. You have increased the octane level of the fuel. Unlike the avgas where you’ll be lowering the fuel density and have to jet up to accommodate it... if anything you would have to jet down as toluene has a higher specific gravity (Density) than motor gasoline (mogas).

Interesting article pointed out about the waste of using higher octane fuel in circumstances where the engine doesn’t require it. A stock bike with 9:1 wouldn’t gain for example. But your race motor or 10.5:1 spitfire engine would. I tried an expensive octane booster in my bike when it was still pretty stock, it made no difference so poured it in my car, thought it was more voodoo than anything else.... the car liked it sure enough.


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Kevin, use Google and there are some formulas for home made racing fuel. I believe a few were on Speedtalk...The local non control tower small airport has a 24/7 credit card fuel pump but you need to enter a tail number. I called during the day and the manager said he would sell 100LL for an off road bike, if I call him before coming with a fuel can..
My opinion of it is similar to Nick but I do know guys who blend it with pump gas for engines prone to detonate on pump gas....I ran left over leaded race fuel in my street bikes several times....they ran the same but the Tel left a white color inside the tailpipe like the good old days...
And you can buy real TEL fuel additive in the USA. It's a bit pricey, Google Octane Supreme. I used this stuff 15 years ago and it does work


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well, i confess my curiosity is mostly academic. in my higher-compression race machine i use VP C12 exclusively for consistent tuning. the only time i ever saw evidence of detonation was with a single-plug head and 38 BTDC. i switched to a cooler plug and the detonatio appeared to go away.

i know the difference between detonation and pre-ignition, but that is what worked.

now i continue with C12, but use twin plugs and 30 BTDC. still with B9s, no evidence of detonation, but i'll try B10s this time out as an experiment. if they'll run without fouling i'll use them. dan at franz and grubb has emailed that NGK is phasing out B6, B7, B8 and B9ES. they are being superceded by resistor plugs that aren't specced for magnetos. i'm going to buy a shitload of 8s, 9s, and 10s.

on my street machine, it works fine with B8ES and 9.5 to 1, with ordinary 87 octane unleaded ethanol gasoline, at any hill or throttle position i can find without specifically trying to abuse it.


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Things move on, avgas is old hat and has been for years.
It was a fix as it's slow burning allowed plenty of advance,
with faster burning fuel you can retard the timing and actually
get an improvement in bmep.
But i can't really say too much as i used to run R type oil, it
was only 'cos of the smell, i knew it was old hat back then.
20 years ago, just like avgas. Nostalgia eh?

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