What Octane to run?

[hossman]

My dealer said to run 89 in it, yet the owners manual says 87. So which is correct? Am I wasting money on the 89 since the engine has such a relatively low compression?

 

[CanberraR3]

In my opinion, yes, you are wasting your money. Not doing any harm though.

 

[BillB]

In my opinion, yes, you are wasting your money. Not doing any harm though.

+1 on that

If you want to spend more on fuel go here and see if there are any places near you that sell gas without a bunch of alcohol mixed in it. http://pure-gas.org/

Usually pick up about 10% mpg

BillB
2013 R3T

 

[TURBO200R4]

My dealer said to run 89 in it, yet the owners manual says 87. So which is correct? Am I wasting money on the 89 since the engine has such a relatively low compression?

i know that the gas pump says 87 or 89 but i have bought 89 and two blocks later after it goes into the carb the motor would start pinging on my el camino. you will never miss the 30 cents extra when you fill up.
of coarse if you get bad gas the rocket will probably decrease timing to take care of it.
just my opinion
herman

 

[rocket51]

My bike runs just as good on 87 as it does on 89 or 93. I think it is a waste of money if the bike doesn't run any better with higher octane. I do wish we didn't have to deal with the ethynol in gas, I get 3 to 5 mpg better on straight gas. There are not many places in Texas to get straight gas and the ones that do have about 20 to 30% increase in the price. I can drive into Durant, Oklahoma 35 miles away and buy straight gas as cheap or cheaper than ethynol gas here.

PS: Staight gas in the U.S. is getting to be rarer and rarer especially in the southwest. In the U.S. we are forced to pay tax dollars to support something that we don't want and that harms our motorcycles, cars, and other motorized equipment. Our experts are ruining so much in our lives with their great knowledge.

PS2: sorry about misspellings: does the forum have a spell check that I haven't seen?

 

[El Toro Rosso]

My dealer said to run 89 in it, yet the owners manual says 87. So which is correct? Am I wasting money on the 89 since the engine has such a relatively low compression?

In the US, the number on the pump is the AKI (anti knock index). Its equal to the average of the MON (motor octane number) and the RON (research octane number). How a fuel actually performs is dependent on the AKI and the Sensitivity (the difference between the MON and the RON). And then there is the calorific value, and the propensity to combust (combustion efficiency).

I've had two different R3Ts. I live in a hilly area, and I used to weigh 340 pounds.

What I noticed is that, under heavy load (340 pound me going up a steep hill at 50 mph), there is a tendency for my Rockets to knock. A downshift can take care of it with nearly any fuel. It is less of an issue with real 93 octane gasoline.

Under lighter loads (224 pound me on a level road) my Rockets don't care what the octane level is, but I still prefer real 93 octane gasoline.

Right now, there is a lot of research being conducted that shows that higher octane fuels have the potential to be more efficient under modern engine control and sensing. As the US moves towards the 2025 CAFE target of 54.5 mpg, higher octane fuels are expected to play a role.

As for the gasohol (typically E10 nowadays in the US), the difference in mpg that most people will see is on the order of a few percent. The calorific value of the fuel on a gravimetric basis is very close to normal gasoline (E0). The actual weight per gallon for the E10 is slightly higher than the E0. So it turns out that the real differences are small, and most likely attributable to driving habits, and wishful perceptions.

I could get anywhere from 33 mpg to nearly 40 mpg out of my R3Ts. The biggest factor seems to be city vs. highway, and the right wrist.

So ... after all that BS, what do I do?

I buy the 93 octane premium gasoline that they sell near the lake for boaters. Its got the full complement of additives (anti foaming, detergent, etc), and its blended so that the AKI is at 93. The chances of having a fuel problem with this stuff is somewhere between 0 and epsilon.

If I'm on a trip, I nearly always end up with E10, and if its in one of the highway robbery states where gasoline is typically 30% more than in my home state, I'll buy the 87 regular grade.

 

[idk]

The original RIII handbook said to run it on 89, in about 2008 (ish) the RIII manual said to run it on 87. I called Triumph USA and spoke to their chief technical bloke (I can't remember hi name) and asked the question. His answer was that the RIII will run on 87 and there is no reason to put 89 in it - unless it "pings". So if yours is not pinging then 87 is fine. If it is pinging on 87 then get it tuned properly.

 

[El Toro Rosso]

His answer was that the RIII will run on 87 and there is no reason to put 89 in it - unless it "pings". So if yours is not pinging then 87 is fine. If it is pinging on 87 then get it tuned properly.

So basically, retard the timing until it no longer pings.

Of course as you retard the timing, you're also diminishing BMEP (brake mean effective pressure).

Most engines are timed according to MBT rules (minimum advance for best torque) unless the timing is knock limited (KLSA - knock limited spark advance).

KLSA timing, by its nature, means that you are not reaching your torque potential.

Maybe this is why so many Rockets only hit 135 ft-lbs on the dyno, but the factory spec is 150. They detuned it further for touring, with the expectation that you'll be visiting areas where high octane fuel is not available.

 

[joey fletcher]

Just running around here I run 91-93 octane Plus a shot of 108 octane boost

If I plan on playing hard....I will ride about 25 miles and get 112 octane racing fuel to go into the Ol' Girl.

I know it may be a waste of money but it sure smells good....also makes me think I am going faster...

 

[idk]

Maybe this is why so many Rockets only hit 135 ft-lbs on the dyno, but the factory spec is 150. They detuned it further for touring, with the expectation that you'll be visiting areas where high octane fuel is not available.

The factory spec is at the crank. You will loose a bit by the time you get to measure it at the back wheel.