Fuel for old bikes.

[brettxlch]

Why 93 octane? Unless you built a high compression engine and need the higher octane to prevent spark knock/pre-detonation, save money and use 87. Plus lower octane fuel ignites easier at lower compression which can help kick starting. I know some that insist on running 93 but can't explain why its better for their particular stock engine other than its more expensive so its got to be better. Octane is very often misunderstood. I always run the carb dry if I know the bike will be sitting for awhile which really isn't too often other off season.

Yup ill try 87 see how she goes, 2018 harley freewheeler requires minimum of 91 octane, which is not available in my area only 87/89/93 octane..so i have no choice for the trike.

[Skirted]

Why 93 octane? Unless you built a high compression engine and need the higher octane to prevent spark knock/pre-detonation, save money and use 87. Plus lower octane fuel ignites easier at lower compression which can help kick starting. I know some that insist on running 93 but can't explain why its better for their particular stock engine other than its more expensive so its got to be better. Octane is very often misunderstood. I always run the carb dry if I know the bike will be sitting for awhile which really isn't too often other off season.

[59tbird]

You can buy 105 low lead no ethanoll at most airports. Airplanes don't work on corn squeezing.

John W WEIss
24633

[brettxlch]

Thanx guys for all of your input...brett

[T. Cotten]

Sounds like just another "Sportster Disease" to me, Duffey!

(They are out of my zodiac.)

The gas gauge sending unit in my '91 Ranger finally gave it up last summer blend.

Obviously a swollen float.

....Cotten

[duffeycycles]

Starting in the spring of 2007,I had many customers bikes,mostly sportys that did not start or started once died & would not start again.Drained fuel,removed plugs,crank em over to clear & all ran fine.Less problems after 2009 or so but still more issue than before 2007

[T. Cotten]

Just an anecdote, Folks,...

But a few years back an associate brought me a nice "old" gas can, full, from his aunt's garage.

Perhaps '70s or earlier, guessing of course.

But the fuel still smelled sweet.
Ran great in my Toyota.

....Cotten
PS: I guess my point is that modern additives are what sour fuel, with ETOH as prime suspect.

[duffeycycles]

The gas in Iowa varies .91 octane usually has no alcohol,but the other stuff has alcohol.I tell my customers with high compression to let their buddies fill first !When I get a few gallons [premium only]for customer bikes,snow blower,lawn mower,I always put a few gallons in my car first to get past what is in the system.

[T. Cotten]

A gas pump with only one nozzle can give you 2-5 gallons of whatever the last person used before you get the gas you selected

Wow Duffey!

I woulda guessed a gallon at most.

But different grades from the same pump should probably have the same soup of additives.

If you give the P4gas as little to eat as possible its just fine.

....Cotten

[duffeycycles]

A gas pump with only one nozzle can give you 2-5 gallons of whatever the last person used before you get the gas you selected

[T. Cotten]

I wonder if Coleman white gas for lanterns would burn well in the old engines ? Price is over the top though.

It was suggested to me, Pa,..

That a couple of ounces of white gas added to a tank of regular upped its octane to 'premium'.

Just more armchair-engineering without any testing!

....Cotten

[Jerry Wieland]

Tom I never run any additive in my knucklehead either. Usually try to use premium when possible but it runs great on anything. Cast iron guides and stainless valves.


Jerry

I have just over 72K miles on my 1940 Indian 4 since I rebuilt it 40 years ago. It has the original bronze intake seats with Oldsmobile valves. I use the cheapest gas I can find and have never added any thing to it. I very seldom have to adjust the valves. It is running as good as ever and has never had a valve job since the rebuild. I have been draining the fuel for the winter for the last 10 years.
Tom

[Tom Wilcock]

I have just over 72K miles on my 1940 Indian 4 since I rebuilt it 40 years ago. It has the original bronze intake seats with Oldsmobile valves. I use the cheapest gas I can find and have never added any thing to it. I very seldom have to adjust the valves. It is running as good as ever and has never had a valve job since the rebuild. I have been draining the fuel for the winter for the last 10 years.
Tom

[BigLakeBob]

...beyond the ethanol issue, I've read that some people like to add a little Marvel Mystery Oil to their gas. I don't, but I'd be interested in hearing again why it could be a benefit to old motors.

Not exactly old, but for my '69 shovel with med comp pistons and bronze (yes, alum bronze like pans) valve seats, I run whatever pump gas available. Sometimes I put in 87, sometimes 93, sometimes 10% ethanol sometimes not, but I have always squirted 1-2 teaspoons of Marvel in the tanks at fill up for 53K miles. The heads have never been off, comp started at about 135lb and at 50K miles it was 105lb constant/ cylinder. I have had a Tillotson carb on for about 5 years now, it has a repop rubber diaphragm from Tedd's made over there somewhere (5 yrs old), I leave it sit about 4 months over the winter. No rust in the tanks, same diaphragm, bike starts without any hesitation every spring for the last 14 years with no draining of gas or additives over the winter. I am a firm believer in Marvel for top end lubrication, (also possibly diaphragm lube, tank lube). Another member years ago stated that 2 cycle oil would be better because it wouldn't lower the comp ratio like Marvel in his opinion, I agree but have yet to try 2 cycle as a top end lubricant. To each his own, just as oil brands and viscosity goes, but the proof is in my 53K pudding to me. Before that, a '62 Pan with about 25K when motor taken apart for other reasons, the heads with replaced bronze seats are still like new, run with Marvel the whole 25K.

[Paps]

I wonder if Coleman white gas for lanterns would burn well in the old engines ? Price is over the top though.