super vs unleaded

Hello again......
after me and friends riding our flatheads round Greece for many years on Super (gas/petrol)......over the last 2 year or so its getting harder and harder to find gas stations that still sell it.......this year on the anual Handshift Rally not one station supplied it along the 600mile run and we all filled up with unleaded.......
what are the the problems with using unleaded in stock settup motors......is it really bad for the motor etc......
thank you...........

Here in the US unleaded has been the norm for quite some time.I use it in everything I own, vintage H-Ds, Vintage Triumphs, Vintage BMWs, etc. Zero issues with any of them related to unleaded. The problems with fuel here are mostly related to ethanol. Hopefully you don't have that to deal with.
Robbie

what are the the problems with using unleaded in stock settup motors......is it really bad for the motor etc......
thank you...........

Where 45's are concerned, there aren't any problems, leastways not with how the fuel burns. The only concern I'd have is the potential damage to the original floats, but one of Moldthread's rubber duck jobs should sort that.

When I got my first 45, the PO told me to run it on one tank of unleaded then one tank of LRP; for the benefit of our American friends, the latter was a stop-gap fuel which the British companies used whilst the changeover to fully unleaded took place, it's no longer available. In conversation with Fred Warr, the doyen of "real" Harleys in this country, I mentioned this, and was told in no uncertain terms that I was wasting my hard-earned. WLA's and the like were made to run on a far lower octane rating than would be acceptable today, and so will tackle unleaded quite happily. The fact that flatheads , in fact most Harleys, burn a certain amount of engine oil helps matters as this acts as an upper-cylinder lubricant.

As for OHV motors; my 1972 Ironhead runs quite well on 95 octane unleaded. I do treat it to the occasional tank of 98 octane if I'm going somewhere where its performance may be utilised more fully than normal (off the public highway of course officer) but it hasn't shown any signs of valve seat deterioration yet.

Since I was a kid I have been warned not to use high octane fuel in air cooled flathead engines. The warning was it will burn the valves.

The only concern I'd have is the potential damage to the original floats, but one of Moldthread's rubber duck jobs should sort that.

Kev UK!

Don't underestimate P4gas!
It swoll both RD and Starklite "Nitrophyll" floats in the Pacific Northwest last season.
Its not just the ethanol.

Too heavy anyway.

Extra octane just goes out the pipe like the extra cash out of your wallet.
If anything, higher octane fuel will only prevent the motor from warming up as quickly.
Please remember that the optimum temperature for a Flatty is a hundred degrees hotter than an OHV, and that is why it burns hotter low-octane fuels

....Cotten

[Pa]

Geeze.......maybe I ought to keep my stashed brass float ???

C'mon, Pa,

You know there is still a better formula float.
The swollen Pacific Northwest floats were replaced with DURABLEs,
and so far, no news is good news.

....Cotten

[Pa]

No news is good news.

Running unleaded in a engine with castiron valve seats does require some kind of upper cylinder lube to replace the lead which is a lube at cylinder temps. Or you can install hard seats. Ive had great luck with a half cap of Marvel Mystery oil or ATF in every tank.
Dusty

Gotta be careful here with my choice of words, or the "transatlantic language barrier" will kick in!

Dave, I'd agree with you up to a point. The biggest problems with valve seat recession over here have been with the "A-series" car engines as fitted to the Morris Minor, MGB Midget and the like. Standard procedure is, as you mention, to fit hardened (stellite?) valve seats.

There is also a theory that if an engine has covered, say, 40,000 miles on leaded fuel, it should do about half as much again on unleaded before any problems occur; I believe it's called "residual lead" or some such like. Goes without saying that on many older British engines, this will co-incide with a rebuild anyway. I understand that American car engines, apart from being more advanced than ours regarding lead-free technology (since you had it long before us) tend to be built to run higher mileages before overhaul is necessary. I put this down partly to the way things are Stateside, with your tendency perhaps to do longer runs at a steady speed than we have cause, or even space, to.

High-performance British bikes like the BSA Gold Star tended to be run on what we called 5-star fuel, above 100 octane. It was never available everywhere, and IIRC went out of use in the early 1970's. Its demise was due to the gradually-reducing amounts of tetra-ethyl-lead, which as you probably know is the halide added to gas to reduce detonation. Back in the day, any vehicle which had been run on that stuff, but only around town, would show a tell-tale white discharge around the exhaust pipe. The standard "Back street garage" cure for this was a fast thrash along the freeway!

The Morgan Owners Club produced some quite learned and interesting articles from one of their members on the subject of leaded fuel, and acceptable substitutes. I'll see if I can find it.

Let us not forget, Folks,

Tetraethyl lead was introduced to increase octane rating, not to prevent valve seat damage.

"Ethyl" was higher octane than the Rider's Handbooks specify for Flattys.

Modern accelerated seat damage should be blamed upon modern additives, not the lack of lead.

....Cotten

[Pa]

I like addind Marvel Mystery Oil to the fuel as well but I would think even a bit of 2 stroke motor oil would suffice as well. Marvel smells much better though.

What I was taught back in the Eighties, Folks,

The modern seat erosion problem is a micro inertial spot-welding process, slowly "burning" tiny bits of metal from both valve and seat.
High-nickel hardened seats are only a little better than cast-iron in resisting this phenomenon.
Stainless valves can be death on cast-iron seats, because of the affinity of nickel for iron.

Lead inhibited this "spot-welding", not a a lubricant, but as an insulator.

....Cotten

[Pa]

That sounds real logical Cotten.

I don't think they put lead in gas until the late 40's to boost the performance of the big straight 8's..to reduce ping @higher rpms....the flathead would run on 62 octane(almost diesel fuel)so I think 87 octane unleaded is plenty...peace, Paul