S40 Which grade of gas?

S

Shanequa

New member
Hi,

I just got a 2006 S40, no manual, which grade of gas does the bike run on?

Sorry for the simple question but I can't get a hold of the previous owner to ask him.

Thanks,

Rob:fight1:
 
IF I use 87 on my new C50T, I get a lot of valve noise. I went through all grades, and settled, right now, on 91. I get the least engine noise with it, and 93, but 91 was the lowest denominator.

You may want to experiment with grades, and take your pick. The engine is designed to run on 87, but timing is tight with new engines. These engines don't REALLY beak in till the 12 - 16k mark anyway. Once the engine "loosens up" (just a simple term), then you can go back down to 87. My uncle has had his volusia since 04, ran 91 till he got about 12K, when he was able to go back to 87 with no excessive engine noise.

I am sure the expert will chime in, but this is MY experience, and what I am doing, and will do till I break 12K mark and revisit the 87 octane scene again.

Stay with 87 till your initial break in period, as higher octane runs hotter in the cylinders.
 
I have been running 87 since the day of purchase with zero miles and zero problems. My understanding is that lower octane burns more quickly than high octane and thus is more fully and evenly ignited. High octane will burn more slowly and unevenly which can cause unburned fuel to enter the exhaust system and possibly leave deposits on the valves and potentially ignite within the exhaust system. Unlike today's modern cars our bikes are not nearly as sophisticated. They put those fancy engine computers in cars that can detect predetonation (pinging from fast burning low octane fuels) and the computer can automatically adjust the timing to prevent predetonation. Our motorcycle engines are not nearly as complex and are more vulnerable to such octane varieties. Running too low octane (fast burning) could result in the fuel burning too quickly for the average motorcycle engine burning the fuel before the piston has come to tdc and thus working against the engine, and possibly damaging it.

A fine line but there you go. Don't know if it is all correct but as I said this is my understanding.
 
87 posted in the manual. As "Frostbitevinnie" states, low detnotation is a fact in higher octane fuel. This fuel is better suited for High compression engines which can properly compress the higher octane sufficiently and with the low detnotation ignite them when required. The low compression ratio of the S40 is much better suited for low octane fuel which can ignite faster and when needed. Interestingly enough, in these cases a smoother running engine and more power translated to a lower octane fuel. More is not always better...

Hope this helps...
 
I was reading an article not too long ago concerning octane vs performance. The test was performed using a standard sport bike. With 87 octane they actually got 10 more hp over using 110 octane.
 
Back
Top