Yea, but I was also running the 87 in the same conditions. With the premium, bike had some kind of strange vibe too.
85 Octane in The FJR
- Thread starter LAF
- Start date
Help Support Yamaha FJR Motorcycle Forum:
BackintheSaddle
Well-known member
There was a magazine article (possibly Hot Rod?) a number of years ago where they ran track laps in the same car with regular and "high octane" fuel. The car was not equipped with engine managment systems that could adjust timing on teh fly. They left all the timing, fuel, etc the same and the car was slower around the track on the high-test. The conclusion was the slower flame propagation due to the "anti-knock" charateristics cost the engine a few horsepower. You need more advance to get the combustion started earlier in teh stroke in order to get it completed (near completed) before the bottom of the stroke and the exhaust valve opening.
The modern cars with dual ratings (SHO is another) take advantage of the fuel charateristics by letting the ECM to push all the parameters to the maximum unless the knock sensor says "whoa."
The modern cars with dual ratings (SHO is another) take advantage of the fuel charateristics by letting the ECM to push all the parameters to the maximum unless the knock sensor says "whoa."
IF the base motor is built to the higher octane in the first place. Otherwise it can only do what it was built to do. If that happens to be a build-to-87, then that's what it will perform best at and the ECU can only do "up to" that.
Take my STi. It was designed to 91. I got a custom tune that pushes more boost and it's tuned to 93. If I have only 91 or lower available, I make sure I don't "get into it" just to go easy on the motor. I've run 100+ (from the pump) in a couple of places just to see and real measured numbers as well as MPG and butt dyno reveals no improvements. At $8 a gallon, it's money down the drain.
The FJR is "built to" 87. You can custom tune it (or even custom build it) to a higher level that can then benefit from fuel combustion retardation (more octane) but out-of-the-box, anything more than just enough to avoid "knock" is, again, money down the drain.
Take my STi. It was designed to 91. I got a custom tune that pushes more boost and it's tuned to 93. If I have only 91 or lower available, I make sure I don't "get into it" just to go easy on the motor. I've run 100+ (from the pump) in a couple of places just to see and real measured numbers as well as MPG and butt dyno reveals no improvements. At $8 a gallon, it's money down the drain.
The FJR is "built to" 87. You can custom tune it (or even custom build it) to a higher level that can then benefit from fuel combustion retardation (more octane) but out-of-the-box, anything more than just enough to avoid "knock" is, again, money down the drain.
Last edited by a moderator:
The thing that is freaky with the FJR is that when you read the specs and see 10.8:1 comp ratio, you immediately think premium fuel.
C&C
Well-known member
Compression used to be the most common denominator in octane requirements. Modern engines have evolved, and even as compression still contributes as a factor, others include, combustion chamber design (and in some of the newer car engines, direct injection).
Top_Speed1
Panama Canal Crosser
If the Feej is built to run on reg Octane, I'm pocketbook happy then. As said my Super-Charged Jet Skiis and other hi-perf toyz sure don't likey the low stuff
RadioHowie
I Miss Beemerdons!
Key phrases highlighted.....speeling errrors igorned. :finger:If the Feej is built to run on reg Octane, I'm pocketbook happy then. As said my Super-Charged Jet Skiis and other hi-perf toyz sure don't likey the low stuff
Top_Speed1
Panama Canal Crosser
Howie, I use to think the FJR was Hi-Performance?Key phrases highlighted.....speeling errrors igorned.If the Feej is built to run on reg Octane, I'm pocketbook happy then. As said my Super-Charged Jet Skiis and other hi-perf toyz sure don't likey the low stuff
And yes, alwayz ignore schpell'n (or propha grammar) on deese forums
RadioHowie
I Miss Beemerdons!
The Feej is "High Performance" only because it's 145 ponies in a 600 pound package. It' really no more high performance than a run-of-the-mill Honda Civic. Add another 2000 pounds and a Civic would give it a serious run for its money.
It's really NOT a hi-perf moto. It's really just a station wagon missing 2 wheels and a ton.
It's really NOT a hi-perf moto. It's really just a station wagon missing 2 wheels and a ton.
Last edited by a moderator:
HotRodZilla
GOD BLESS AMERICA
Nothing like a thread such as this to remind me how totally full of **** some people really are.
RPrice
Fish Cop (retired)
Hello Bob!
I'm going to ride from Cedar up to your area around the 3rd week in August. I have a friend coming with me on his '12 FJR.
If you are not too busy maybe we could ride together some and burn up some of that Idaho 85 octane.
John
RPrice
Fish Cop (retired)
Too busy??? Hell, I'm retired!! I'll look forward to seeing you guys, I'll shoot you a PM. We'll have an excellent time on these twisty roads around here!
SoCalFJR1300
Well-known member
Justin
Well-known member
FJR runs fine on the 85 here in CO. The Busa runs better IMO on the premium. I usually put 87 in the FJR, just to be safe. Just because you can't here knocking doesn't mean it's not happening at a very low level. I'm willing to spend the extra 5 cents a gallon to feel all warm and fuzzy lol.
Last edited by a moderator:
LAF
Well-known member
And that is why I started this thread. I could care less about 30 cents on a fill. However I had never seen 85 being on the Right Coast and wanted to know. I ran it the whole time it was available to me with no issues. I still only run 87 here in PA and have since I owned the bike.
wfooshee
O, Woe is me!!
The difference is altitude. 85 at altitude equates to the same knock resistance as 87 at sea level. Lower air density means lower absolute pressures inside the engine.
LAF
Well-known member
I suppose this is interesting info to some. It has been known for ages the reason and need for octane levels. It is amazing how uninformed people are regarding the proper use of octane levels. I have ridden my FJR's over all the western states and never put anything other than regular octane (whatever level). I have averaged 46-49MPG on all rides. Save your money and use regular fuel from a reputable supplier.
I believe you are right Art.
Out of curiosity I sent this question to Toyota since I had recently purchased a new Tacoma.
Here is their answer. The question I sent is after the answer.
Thank you for contacting Toyota Motor Sales, U.S.A., Inc. We appreciate the opportunity to address your inquiry.
We apologize, The recommended octane for your vehicle is 87 or higher. The Tacoma has not been tested with an 85 octane and using it may affect performance and/or reliability issues.
If we can be of further assistance, please feel free to contact us www.toyota.com/help/contactus.html.
Customer By Web Form (John Foster) 10/03/2012 12:29 PM I recently purchased a Toyota Tacoma with V-6 engine.
My home town is located in the Rocky Mountain area at an altitude of 5800'.
It is not unusual for me to drive in areas varying from 3500' to 11,000'.
All of the regular gas at the local stations is 85 octane.
Is there any problem associated with using 85 octane regular in this area.
