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Unleaded vs. Super Unleaded

13K views 23 replies 13 participants last post by  Brigstocksbobber 
#1 ·
Just for an experiment, I thought I'd try a tankful of super unleaded the other day. I wasn't expecting anything in the way of a performance boost but the engine did seem a bit smoother and less snatchy going from closed throttle to open.


Is it my imagination or is this to be expected?


(I've got US spec Vance and Hines pipes plus an appropriate tune from the dealer - no other engine mods)
 
#2 ·
I have filled with both regular and premium, but have not really noticed a difference. I have the booster plug, so not sure if that assists in anyway regarding variances in octanes. I have always thought that premium burns cleaner than lower octane levels, but I am no chemist to say why.

I put premium in 2 of my 3 cars, but that's because it requires it.
 
#3 ·
I definitely felt a difference in my air cooled r1200r when I had it, but can’t say I really feel a difference in the newer liquid cooled GSA or Bobber.
It’s been a while since I filled up with super unleaded on the Bobber, so I’ll give it a go the next time I refuel. The results may be more tangible now since I’ve had my ECU remapped by Hilltop.
 
#4 · (Edited)
The super unleaded is probably better, but its a substantial price hike. I use it in my car as its direct injection. I agree with muensterDeath I think it burns cleaner so reduces the chance of carbon buildup in the intake, but as the bike doesn't use DI I dont mind using regular unleaded. I used to have a Mitsubishi DI car that was prone to problems with carbon buildup in the intake due to exhaust gas recirculation. The same model was sold in Japan and they claim they never saw the issue. The only difference was the Japanese fuel was generally equivalent to super unleaded.
 
#6 ·
From what I have gleaned over the years from various sources the higher octane fuels have additives to prevent pre- detonation/knocking in engines with high compression ratios. There is no gain in power. It is possible that some engines are on the cusp of needing higher octane and therefore feel "happier" with a mid to premium fuel.

Chico
 
#9 ·
I've only ever run premium in my bikes. I did once use a tankful of regular in my dirt bike and noticed it was harder to start and felt a bit off. I believe premium is also less likely to deteriorate over time thanks to the additives which is ideal for the bikes which sometimes go months without use. A mate of mine with classic cars also uses premium exclusively for the same reason and he also reckons premium preserves the rubber fuel lines better.
For the extra couple of cents I'm happy knowing my baby is being fed the best diet ?
 
#12 ·
At quick glance from the Car Talk site (hilarious to listen to on PBR), it confirms what I've been told.


The additive in premium gas that prevents knock is octane. Octane is a fire retardant, it slows detonation so that it does two things: eliminates knock in high compression engines, and subsequently reduces heat as you don't have two detonations going on.


Most motorcycles nowadays require high octane gas. This is because they are high compression engines, and air cooled. Even some water cooled (motorcycle) engines require air cooling, which is why the Triumph has largish fins on the head - to assist the water cooled engine.



My Harley is an air cooled 95ci (1550cc) engine. It requires premium to prevent knocks, but also to lower the temp of a strictly air cooled engine. The size and weight of the HD (full dresser) is very heavy. Add a pillion rider and gear, even that engine works hard. You really do need premium.



My BMW K1600 requires premium. It: a) has no fins and is tucked into the plastic body work, and b) is a strictly water cooled engine. It is a high compression 6 cylinder engine. For these reasons, it does need premium.



Our Triumph Bobber is a duel cooling engine. It uses air and water liquid cooling. It also has a 1200cc engine that is rather excessive for the size and weight of the bike. There is really no way to overload the bike. A 650cc engine would be adequate. Under these conditions, regular gas works fine.
 
#19 ·
That logic is ridiculous. Seriously it is. Compression, timing curves, throttle input, and many factors come into play on detonation.
I have flowed & skimmed the head fitted a performance cam, ran 110hp on the dyno with NO signs of detonation on cheapo standard fuel.

Yes premium has more additives & is better for high comp & or hot motors, simple fact is it is wasted on the stock bobber.

If some people feel they are doing their bike a favour running top grade fuel it is their money & their bike so good luck to them,

I'm sure the petroleum companies are grateful the advertising is working for them.
 
#16 ·
That’s exactly right. I would assume that the bike is set up to a global spec that would allow it to run on 87 (standard) octane fuel with no issues.

Only some type of modifications to the bike would cause a need for anything different.

I remember when the map was loaded on my bike, the option was listed as a North American Vance & Hines 91 octane (if I remember correctly). I would assume that the map probably has a slightly more aggressive timing curve that would lend to the recommendation for 91. 87 would probably still work fine in all but pure performance situations.
 
#22 ·
Zoinks! Didn’t mean to stir up this hornet’s nest!

I don’t really care about the cost (my Bobber’s my only internal combustion vehicle). It just feels nicer with a bit of premium.

The bad vibes merchants (no names mentioned) can grump all they want - I just like to enjoy my ride as much as I can!
 
#23 ·
On the bobber I did do a couple of back to back tanks both round town and out on a run to see if there was a difference and to be honest I couldn't tell in any way shape or form if there was.

However on the landlords R6 into the red at some 15krpm plus, i think it does make a bit of difference, tho losing a stone would probably outweigh the increase and be a damned sight cheaper over the course of a year
 
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#24 ·
So £10 for the regular and £11 for premium, its what you want to do, if I have a money off voucher she gets premium, just to give her a little internal clean through, does it work???? I dont know but it makes me feel better, otherwise she gets regular, until she deserves better.
I have to tried to concentrate long enough when using different octane levels, but give up after about 5 miles of hoolin about whatever is in the tank, and the mileage doesn't ever appear to change whatever is in the tank, even when riding conservatively it all looks great for half a tank, then eventually it hits a quarter, the light comes on and the remaining miles is the same and the total ends the same.
Enjoy the bike, if it doesn't make you skint put in the good stuff. Or as Ethariel states, loose some weight and get better fuel economy.
 
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