is it safe to run my '81 gs650g on 98 octane fuel???

[wardy]

is it safe to run my '81 gs650g on 98 octane fuel???

[Doctor Shifty]

Very definitely, but not really necessary.

My 81 GS1000G runs well enough on 92 octane, I normally run 96 as it is a bit smoother, and 98 is probably pouring a bit too much money into the atmosphere.

Remember that the octane rating is not the power rating, it is the degree to which the fuel resists pinging, or knocking, under compression. The reason for high octane fuels is so that high compression motors can operate without preignition (pinging) happening in the combustion chamber. Too much pinging and you can crack the top off the piston, but such drastic results mostly belong to turbo motors under high boost. These old GS motors are not really high compression and don't suffer from knocking very much.

If you hear the motor pinging under acceleration, especially up hill, then you might consider moving up the octane scale, but only after having the carbies checked to see if it is running lean.

Another consideration is that the octane rating changes according to the country. Japan and Oz use a standard called RON. The US uses a different standard and their numbers are higher for the same fuel. Our 92 is probably US 94 or 96. Some non-Jap Asian countries use the US ratings. Europe uses a third rating I believe. Fun, isn't it?

If your motor is worked over, use a higher rating. Other than that check out the lower ratings and save some money. $1.35 per litre here in Bathurst for 96 is already high enough!!

Kim

[Clone]

As a rough conversion, outside NA to NA fuel ratings,
92 is regular or 87octane
95 is mid grade or 89-90 octane
98 is super or 92-93 octane
My bike usually has a diet of mid grade, but runs just fine, no pinging on regular.

[Doctor Shifty]

Another element designed to confuse the consumer here in Oz is that the companies are now starting to call their product by names instead of giving an octane rating.

What used to be things like regular and super and high octane, became 92, 96 and 98, but are now getting names like Vortex, Optimax, 8000, or Ultimate, with no reference to octane rating at all.

And we are also getting some fuels with methanol added and you have to look very carefully at the pump before you will see the little three inch square sticker that tells you.

Kim

[wardy]

thanks for the advice!

[JMHJ]

My '83 850 owner's manual calls for "at least 85-95 pump octane (R+M/2 method) or 89 octane or higher rated by the Research method. If engine pinging is experienced, substitute another brand as there are differences between brands."

[GS750]

What used to be things like regular and super and high octane, became 92, 96 and 98, but are now getting names like Vortex, Optimax, 8000, or Ultimate, with no reference to octane rating at all.

And we are also getting some fuels with methanol added and you have to look very carefully at the pump before you will see the little three inch square sticker that tells you.Kim

At all the fuel stations Ive been to lately they have the octane rating in the product name sticker on the pump. Ie: on the BP ultimate you will find the 98 octane written just below the ULTIMATE.

[GS750]

Re: is it safe to run my '81 gs650g on 98 octane fuel???

is it safe to run my '81 gs650g on 98 octane fuel???

I have personaly found that with standard Aussie unleaded in my GS750B I get 190Km off 16 litres

With premium I get 220km to 16 litres, and with 98 octane I get 250++km from 16 litres.

The bike runs alot smoother on the 98, has sh*tloads more accleration, and I always run it as standard because I dont mind paying the 10 cents more per litre over standard unleaded for the benefits it poses to me.

I have not altered my ignition timing or anything else to run it, just stuck it in the tank and away I went!