What do you recommend for Octane in Winter?

Most of you know, I am a street guy coming to the dirty side of riding. I always use 93 octane in winter for my street bikes for easier starting on the cold days with the lower flashpoint of higher octane. So far no complaints to the quick start in Winter.


My 426 is kick start only and would like to do some trail riding this Winter and thinking the higher octane is better for a quicker start on the cold mornings. Do you recommend this for our thumpers or sticking to the 89 I have been putting in it for power?

Octane is resistance to detonation. High octane is less explosive than the regular stuff. It won't make your bike start easier. Use the lowest you can while avoiding detonation. It's a fine line between making power and avoiding pre ignition. Use what Yamaha recommends.

Octane is no where near as important as a properly tuned and clean carb, new plug, fresh valves and proper clearance, when it comes to starting.

Yes, I understand and know of the detonation factors. My vintage and modern bikes are all carbed, there is a difference in fuel on starting them on a cold 25 degree day with a carb'ed street bike. 93 starts them right up, but don't power them fast due to cold streets and cold tires don't mix.


Whereas the WR, I want to use the power for trail riding and worried with the carb it is going to be a pain in the d!ck to start in the cold.

Use lighter oil like 5w40 or 0w40 in cold weather. Makes for much easier cold starting.

I believe Rotella is 5w40 I believe, I maybe wrong. Just did an oil change the other night.

There is sometimes a correlation between octane number of a fuel and how well it does cold weather starts, but there shouldn't be, and the octane number of the fuel is not to blame for it.  The problem is a matter of how the fuel blender went about achieving the higher octane. 


In fact, most of the time, you will find that there is a summer and a winter blend gas available in your area.  What one sees quite often is a sudden change in weather toward the colder, and you have cars and gas stations both suddenly stuck with a bunch of warm weather gas for a while.  More people buy regular than premium, so it sells out sooner and is replaced by the correct winter blend.  People with a load of premium start having cold start issues, and somebody blames it on octane.  They fill up with seasonally correct regular, "solve" the problem, and the myth is reinforced. 


It's not the octane, it's the fuel blend. 

What's recommended for the WR?

89 or 93?

I've been putting in 93 as that's what I've always put in my street bikes...

But about to tune the carb so I should get the right stuff flowing if it's not 93

The WR should use pump premium at a minimum of 91 AKI (R+M/2).

The WR should use pump premium at a minimum of 91 AKI (R+M/2).


Oops, I have been using 89 octane, but with no problems so far.

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