Triumphrat

I have a '99 Legend. I have been using premium 91 octane. I just filled up with the plus grade 89 octane. What is everyone out there using?

99 Adventurer been running premium 91 + have not tried anything else. I thought the manual called for premium

always premium for my tbird

j98sprint

You're wasting money if you use anything more than what your manual calls for. I use 89 octane in my carbureted 900.
j98sprint.

Premium always.

.. around here .. the difference in the cost of a tank of regular and a tank of premium is less then $40 cents.

Octane directly relates to compression and ping, the higher the octane rating the higher the fuels ablitiy to be compressed without pinging (detonation by compression not ignition), therefore high compression engines require higher octane. Purchasing higher octane fuel is a COMPLETE waste of money. 98% of all cars in the USA can run on 87. Most turbocharged & high performance cars need 91. Most new sport bikes need 91 as well. Regards, CT.

Will

I had a Bandit 600 that would happily run on cheap gas in cold weather but needed higher octane to keep from pinging at low revs in hot weather. Go figure.

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Will
It's a squid thing. You wouldn't understand.

jefftarlton

If it doesn't rattle on regular or show signs on the plugs you are wasting money to buy the plus or premium grades.
My pickup pings so it gets 93 octane while my bikes all run well on regular. I'll admit this seems wrong unless you study internal combustion.
Jeff

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jeff tarlton

Hi, LegendTom. I'll throw my two cents and personal experience into the hopper.

First, what I learned in my fuels class: As CT pointed out, octane ratings essentially are anti-knock. Higher the rating, less likely to ignite under compression. High compression engines need higher octane. Using high octane in low compression engine means that fuel won't ignite (plugs foul); using low octane in high compression engine means fuel will ignite too soon (detonation, ping).

Ironically, if you make a habit out of using high octane when you need low octane, you end up causing carbon buildup in cylinders; then, you've effectively reduced combustion chamber, increased your compression ratio, and create an artificial need to keep using higher octane.

That said, I don't think that it's always a "waste of time" or a waste of money to use varying octanes. Modern cars (unsure about Triumph motorcycles) have knock sensors. Depending upon the octane, they help adjust the timing and performance, so that if you use a higher than recommended octane, your performance profile changes without harm to the engine.

As for my Triumph, I also have a Legend. The manual says "minimum" 89 octane. Well, when my bike was new, I tried 89 octane. Bike pinged; performance sucked. I've been using 91 octane ever since and am quite pleased....Jerry

Well, I'm never too old to learn! In light of the comments, a couple of weeks ago, I started to ween my Legend off 91 octane back to 89. I'm on my second tankful of 89. I could swear that there is a difference, but so far, it seems to be running fine. I'll keep you posted on progress...Jerry