Gas, Go-juice, Guzzoline, Dinosaur Whiskey; whatever you decide to call petrol, are you putting the ‘good stuff’ into your machine and do the funny little numbers mean anything?
Fuel is the bugbear of the motoring enthusiast: we know we have to have it, we just all hate paying for it. ‘Excellent, I just filled up at $2.20 a litre’ said nobody, ever. Today, we are faced with all sorts of variables when it comes to the fuel we can use, so which is best for your bike? The answer is actually quite simple if you have a modern machine: run what the manufacturer tells you the engine is designed to run on.
Regardless of whether you think it’s a rark-up or not, if you have a bike built from 1980 onwards, it’s a safe bet to assume that what the manufacturer says, goes. Why so far back? Around the 80s is when we started to see higher compression engines and pesky things like elementary ECUs arrive, to control fuel flow into mainstream engines.
When you start getting into the more complicated tech – which makes your machine go so much better of course – you do have to pay a price, and the price of buying a higher grade of fuel is a small one to pay – even if it doesn’t feel like it at the time. As to the higher compression engines, this is an area that we, as motorcyclists need to really pay attention to. The greatest percentage of motorcycle engines are high compression engines requiring higher octane fuels, to protect them from damage.
So, what is defined as a high compression engine? In very generalised terms, a compression ratio of 10:1 would be considered a high compression engine. If the specs for your bike show 10:1 compression or higher – your bike needs a high-octane fuel so, move along from that green handled pump, fella. You want the red stuff.
And before we get some readers coming back with, “I put this octane boosting additive in, so I can run crap fuel if I want, and save myself the bucks” we’re not going to tell you that’s right or wrong. We are merely talking fuel here, additives are a whole ‘nother ballgame.
There are some exceptions to the year thing though. If you happen to be running something like a 2018 DR200 say, with its 8:1 compression ratio, knock yourself out, and run whatever fuel you fancy, barring diesel of course. The engine is strong, reasonably low tech and will pretty much do what it was designed to do, since it was designed to run on a lower octane fuel in the first place. It’s the compression ratio you need to be paying attention to. Putting a high-octane fuel into a low compression engine however, is probably a waste of 30 cents a litre for all the performance benefit you’ll get.
To do better with the mileage, we’d recommend slapping on some decent hoops, and yes, that will make a difference. As to the power, you could look at raising the compression which would therefore require you to run higher octane fuel, or you could ease off the doughnuts, dude!
Ok, you ask, so what is all this to-do over octane ratings and what do all the funny numbers mean? Two questions, so here’s two answers: The first answer is that a higher-octane fuel allows engine developers to improve reliability, efficiency and power outputs using different and improved technologies. Yes, this is a ‘chicken or egg first’ scenario, but it is working, inasmuch as those manufacturer’s improvements enable us to get more out of our fuel than ever before.
And to the second answer; what do the numbers mean? Well, the numbers that you see at the pump – 91, 95 and 98 typically – are there to give you an idea as to the engine’s performance, but not in terms of power or torque outputs.
The octane rating or number, tells you how much compression the fuel can stand before it spontaneously ignites through compression. The higher the number, the more stable, or compression-resistant the fuel is. The more resistant the fuel is, the more efficient the engine can be, which is why knowing your engine’s compression ratio is so important, and not only for bragging rights at the bar. Put in very simple terms, if your engine is even remotely sophisticated, in that it has EFI as opposed to
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