Premium gas for 1980 GS1000s

[gshub]

octanes

One small question the petrol we get over here in England is it the same qaulity as you,
get in the USA. we have had trouble with our supermarket petrol (alegedley)
so im wondering if it would make a differance.

[walt]

My two cents on this. If your bike is in a good state of of tune. Your bike will run fine/best on 87. High octane fuel burns cooler and slower. The best way to make power is to use gas that creates the most heat that your motor was designed to use. More heat and more rapid downward pressure on the piston will result in more HP. If you motor is pinging then you need to investgate. Pinging comes from too much ign. advance, too lean on the jetting or low float levels. The needle jets have small holes that are cross drilled to allow air to mix with the fuel. The air added will atomize the fuel better and give a complete/better burn. Fuel that is not well atomized will not burn as complete and show a lean condition on a spark plug read. We all mostly run our bikes with the carbs somewhere on the needle jet. Those cross drilled holes are as important as to jetting as the size of the mains. Some pilot jets also have those crossed drilled holes for the same reason. Hopes this helps.

[darkbane]

When I purchased my bike, the previous owner said he always runs nothing but high octane, and I've stuck with that as well. But now that I've had the bike a bit, I'm not happy with the way it runs. I'm not a mechanical genious, but it seems like it's getting too much fuel, or can't burn off the amount of fuel it's been given.

I get a lot of black smoke when I rev it up, and if I put my had in the smoke and rev it, it's black and wet. I'm guessing this is gas that isn't burning.

After hearing everyones testimonials on this forum, I'm going to switch to 87 and see what happens.

Peace

[Commodus]

When I purchased my bike, the previous owner said he always runs nothing but high octane, and I've stuck with that as well. But now that I've had the bike a bit, I'm not happy with the way it runs. I'm not a mechanical genious, but it seems like it's getting too much fuel, or can't burn off the amount of fuel it's been given.

I get a lot of black smoke when I rev it up, and if I put my had in the smoke and rev it, it's black and wet. I'm guessing this is gas that isn't burning.

After hearing everyones testimonials on this forum, I'm going to switch to 87 and see what happens.

Peace

I do not think that changing octane ratings will fix any problem you ever have with your motorbike. Well unless you make drastic changes to the engine.

It's time for you to do some investigating. Start with a compression check.

[BrainBucket]

Poor Man's Octane Booster that Really Works- Long Explanation

"Appearant octane", anyway, actual octane can't be "boosted", only bought, as in aviation fuel and racegas, but "appearant" octane means it runs the same, just costs less. Used to use tetra-ethyl lead, instead.
It just so happens that ALL auto/motorcycle makers use, as a standard, 100 octane fuel when they rate fuel economy, hp, ect, that is the testing standard (which is why you never quite get the milage they advertise), and at STP, or standard temp and pressure (of outside air). I used to take my old '79 GS1000 down to the old commuter airport and buy 100 octane AvGas for mine (after running it as dry as I could.. I'd have to borrow their gas can!) and that got me a substantial increase in both power and milage (anyone who'd buy regular 87 oct is a dummy, screw dollars per gallon and miles per gallon, using super 92 octane gets you the most miles per dollar, and is the best for your engine, as well as the best bargain) but I have come up with an even better solution: MOTHBALLS. They made premium pump gas do exactly the same thing, for a lot less money. (poor man's octane booster that works)
But they have to be NAPTHELENE moth balls, there are 2 different types in nearly identical boxes. The paradi-somthingorothersomethingorother type that are the same chemical as the "big white mint" they use in men's urinals, those wont do it. Napthelene mothblalls, 1 per gallon of premium pump gas will have the EXACT same effect (raising the "appearant octane", instead of the actual octane) as 100 octane AvGas, except for the carbon fouling reduction that a motorvehicle won't show, anyway.
I have a "cabin" out in the woods, that uses a generator (the thing carbon fouls all the time, except on AvGas.. it's made to run at one rpm all the time, and at altitude, and that was the only discernable difference between aviation fuel and pumpgas+mothballs, other than cost), it ran about 4 to 4 1/2 hours on pump gas, it ran between 8 and 12 hours with a mothball in the tank.
Suffice it to say that you'll get a lot more whump, about half over better milage (tested and confirmed, normal increase) and I rebuilt a number of my engines and there was absolutely no "harm" done, in fact, they were in better shape than they should have been. The big trade-off is HEAT, your engine will run cooler... MUCH cooler. For every 10 BTU's your engine makes, 9 go out the radiator (or wherever, with an air cooled engine: gasoline is about 10% efficient as a motorfuel), so even a 2% increase in efficiancy, that is LESS heat, means 20% more thrust/milage/HP ("go"). Actually, my math said I got about a 5% increase in efficiency, or about 50% more "go", try it yourself, if you doubt it. The only drawback is that I reeked of mothballs all the time, since I carried them on my bike all the time! The other thing is that mothballs inhibit preignition or "knock", so your engine runs cooler, knocks less, gets better milage, makes more power, by using the highest possible octane 100 or better, mothballs make 100 "appearant octane". In the old days pre-historic gas had tetra-ethyl lead added as an appearant octane booster, or "anti-knock" additive, but it's rediculously poisonous, so they took it out, now all gas is still called "unleaded"
Use 1 NAPTHELENE mothball per gallon of premium pump-gas, drop them in, they'll disolve in a couple of minutes. If you have it down, and especially if you have a trap screen in the filler neck (cars), put the mothballs in FIRST, the gas going in will disolve them.
I have an AS degree in AMT (automotive technology) and I'm an ASE Master Autotech, recognized in 48 states and I have a motorvehicle repair dealers licance in one of them, I know what I'm talking about, and the usual arguments like "it'll burn up your engine" just don't hold up.. actually, your engine will run a lot cooler, and knock less, mothballs leave absolutely no deposits or residue, and any difference in deposits or carbon build up is nullified by any water cooled engine's thermostat. As for air cooled engines, well, I could idle at a red light a lot longer without getting really hot. but there was a slight drawback, it took a tiny bit longer on choke to warm it up, although not much, and I never complained about that, or really noticed it, for that matter.
If you record your milage for tax, whatever, or just know what you spend on fuel, try it yourself, expect 50% more miles per gallon, average.

If you were worried about the difference, low octane will tend to "knock" more, so the timing can't be quite as advanced. New engines with computers have a "knock" sensor, and control the timing with that among it's arsenal of sensors, a computer controlled engine CAN'T preignaite while the computer is in closed loop, that is, when it's at operating temp, however they can while they are cold, or in "closed loop", the computer's solution to "choke" until it gets to 180 degrees. The computer does nothing but flood the engine with the richest mixture until it gets to operating tempurature, the side benefiet is that if the computer fails, the car still runs, just really, really, rich. At least the early computerized cars, anyway. Taking out the thermostat would do a number on them, too. Knock is BAD, that is when the maximum pressure is reached too soon, and the piston is still coming up and hits the flamefront that should be pushing it down, bends rods and valves and all kinds of bad things, pre-computer engines tend to do it if the timing is too advanced, when you dump on a lot of throttle, in too high a gear, like passing without downshifting, when you hear a rattle or pinging sound.... that's BAD. Your older engine has surely been timed to run on lower octane unleaded gasoline, by now, and how would you know, now, if leaded regular knocked less, anyway? I think the fact that any older engines knock at all is a side effect of not running on leaded regular, or low octane gasoline.

[jola]

Sorry to dig up an old thread, but does this octane business vary by engine displacement? I looked in my manual and they mention 89 octane but then they give a range for octane levels that are ok. I have a 450. I suppose I'll just go and experiment with 87 but I wanted to ask first.

[hampshirehog]

When these bikes were new they were designed to run on leaded 2 star petrol - 87 octane. Ordinary unleaded in the UK is 95 RON so you're fine in the UK and don't have to buy the more expensive super unleaded, 98 RON

[jola]

Thanks hampshirehog. :-D

[ohgoodtimes]

So if i am doing mountain riding what would be best, those hills can add some load to the engine and such, so would i want a fuel that runs cooler, but then my understanding is this would decrease power. I think i will stick with the mid grade and then throw a blower on just so altitude no longer becomes a problem......

[doctorgonzo]

Your compression ratio is only 9.2:1 on that engine. There is no need for higher octane gas on that engine. You only need higher octane to prevent preignition in such cases as...forced induction setups, or non-stock piston kits that increase your compression ratio.

I just saw the light on this topic recently. If you aren't getting pre-ignition, do NOT run premium gas. It will cause problems (incomplete combustion, sooty plugs) not prevent them. High octane gas is for high compression engines.

[Dan Ruddock]

I just saw the light on this topic recently. If you aren't getting pre-ignition, do NOT run premium gas. It will cause problems (incomplete combustion, sooty plugs) not prevent them. High octane gas is for high compression engines.

"preignition" is very rare, detonation is common and happens after the plug fires

[doctorgonzo]

"preignition" is very rare, detonation is common and happens after the plug fires

That as well, I was with the majority that didn't understand octane... "wait... you mean lower octane gas is MORE combustible!"

[jknappsax]

The GSes came in about the time unleaded gas was showing up. I remember reading a review of the 1976 GS 750 that made a point that the valves and seats were coated with stellite, so that you could run unleaded and not chew up valves, since you didn't have lead to help lubricate the valves. They also made a point that you shouldn't lap the valves, since they said it would cause premature valve wear. I agree that running regular is the way to go, though I used to run premium, but once I understood the chemistry and the physics, I relented and went regular. As many here have said, if your bike pings, then there is another issue, such as timing or excessive carbon, that needs to be addressed. Detonation will melt, hammer, and otherwise just destroy your pistons.

[psyguy]

low octane gas no longer available

in many european countries you cant buy anything less than 95 octane gas, and this has been so for a number of years now
reading this thread it would follow that their gs bikes run very poorly and suffer lower performance
any thoughts?

.

[mac1170]

gday mate, yeh a lot of drivel on some of these, at what point do you classify an engine as being high comp, ive ran a gs11, on road and track, for 28 years, ran leaded, normal and avgas, and unleaded, all octanes, low octane unleaded is crap, put premium in, your motor will thank you for it in the long term,regards.