Hi Everybody,
What grade of fuel do you recommend for a 75 Ironhead? I put a half tank of 87 in to get it running but does it need higher? I noticed at the local HD dealer they have octane boosters in clear plastic tubes on the parts counter and that got me thinking about a higher grade.

Thanks
Jeremy

 

You should use nothing but high test gasoline. The highest octane rating you can find, which is going to be 92-93 octane.
Today's gasoline sucks!
The Sportster has 9:1 compression ratio and needs the best gas sold. It is foolish to 'mix' one part regular and one part premium. You will just harm the engine, to do what, save a couple of pennies?........... pg

 

Thanks Piniongear,
I'm not looking to save pennys, I just want to treat her right. Do you recommend run the octane booster tubes from the HD dealer then or is that going overboard if 93 is already being used?

 

I do not use the additive myself, but my brother always uses it for his 1958 Panhead. So it will be your choice. Mine runs fine with premium fuel.

The Sportster was designed back when we took 98 or even 100 octane gas for granted. As I recall the Amoco 'White' gas was 101 octane.

Nice gas but I never used it on a Sportster because it was lead free back in the old days before the word enviromentalist was even known.
Lead is needed to lube the valves and seats.
Today all gas is lead free. The octane rating has plunged as well. The proper fix for a Sportster is to have hardened valve seats installed, although my machine is 38 years old and has never had this done...... pg

 

yup, pinion hit it on the head. Nothing but premium in the tank of our old Harleys, and even with that you may still fight problems with pinging.

 

I usually go to my local speed shop & buy 100 octane unleaded but my '73 has bigger domes & shaved heads

 

I also use 93, but I also visit a station that has seperate hoses for each octane fuel. That way I know I'm getting strict 93 octane. I also stay away from locations that add additives (like shell adds nitrogen) or ethanol.

 

or if you can find it.i would check if octane booster has lead added,or buy a lead additive.tis is best for sporty's.of that age.i have an 82 an its set up from fac.to run unleaded.or get new seats an valves,springs,collars,+keepers.they have to machine the heads to put in new seats

 

I've used 93 pump gas on the 900 with no knocking or pinging even at serious timing advance...

 

Be careful adding lead additives unless you have taken a look at your heads first. Your bike may have been converted for unleaded fuel.