900cc Lc Engine - Fuel

Repooh · Sep 30, 2019

I was reading on a.n.other site a discussion which suggested using Super Unleaded was not only pointless but that the 900 engine performs better with standard fuel.

I've been using from day one, am I wasting my money, loosing performance or doing any harm to my Street Twin

BigCLM · Sep 30, 2019

I don't know how the fuel is graded across the pond but here in the States we use the AKI index (anti-knock index). The owners manual says to use 87 (standard fuel). But it also says if the engine knocks, use a higher grade. Using a higher grade will not damage your engine. To save $$ use the lowest grade where your engine does not knock or ping under load.

steve lovatt · Sep 30, 2019

I think you are wasting your money to be honest. I know that triumph do not recommend using it in the old 865 air cooled engine.
Any benefits you might think you get are probably just that - you thinking it runs better!
Save your pennies

beerkat · Oct 4, 2019

I use Super Unleaded (eg. Shell V-Power) in my 1990's Hondas because it currently has less or no ethanol, depending on the petrol company and whereabouts you are in the country. As we know ethanol has a high affinity for water and if left sitting in an unprotected steel tank can result in rust forming. I have had problems with both Hondas (RVF NC35 & CBR NC29), one of which is having it's tank professionally lined as we speak, to make it ethanol 'proof'.
Modern bike tanks and engines are less susceptible to problems caused by ethanol. If you use your bike regularly there will not be a problem.
In terms of performance I doubt you would notice any difference (despite manufacturers claims).
If the ethanol issue is a problem for you then go with the Super, if not then save a few bob but you will not do your modern Triumph any harm by using SU petrol (and neither will it go any faster).

garethr · Oct 4, 2019

It depends...

How smart is the ECU, and do motorcycle engines have knock sensors?

Some ECUs can compensate for fuel quality by retarding/advancing the ignition timing based on the input from the knock sensors.

Some are also clever enough to use a "flex fuel sensor" to run a different map depending on the percentage of ethanol (100% in Brasil, up to 85% in Australia, for example).