octane?
Intermediate
Joined: May 2008
Posts: 30
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From:
RE: octane?
My 02 88" is basically stock and hates anything but 91+. It just will not idle, hesitates, gets lousy mileage, etc. (like it is doing today!!)
Oddly enough, my 92 80" has had cams and a bunch of other stuff, yet it will run fine on garbage - but runs better the higherthe octane. Even on the cheapest swill, it gets over 50 mpg.
Oddly enough, my 92 80" has had cams and a bunch of other stuff, yet it will run fine on garbage - but runs better the higherthe octane. Even on the cheapest swill, it gets over 50 mpg.
Cruiser
Joined: Oct 2007
Posts: 138
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From:
RE: octane?
I usually run mid-grade, which here is 87. Regular is 85 and premium is 91. Course, I am at 6000ft so compression ratio is somewhat less than factory. Probably close to 8.2 to 1 CR, so less octane needed. Also, lower octane fuels , IIRC, have longer hydrocarbon chained molecules, so more energy stored in the extra Carbon-to-Carbon bonds. You will get better mileage out of a lower octane fuel. Just make sure you don't get any pinging. You will need higher octane, if you are in a situation where the motor is going to get hot, to resist pinging.
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Road Captain
Joined: May 2007
Posts: 579
Likes: 1
From: eastern NC
RE: octane?
Thanks all. I put in 87 last night and have riden about 80 miles, 60 this afternoon coming home, riding about an hour, no pinging, no hesitation, no problems with idle and the motor seemed to be running the same temps.
So who knows, ayway I will proberly run the midgrade as long as its not pinging.
So who knows, ayway I will proberly run the midgrade as long as its not pinging.
Road Warrior
Joined: Mar 2006
Posts: 1,807
Likes: 1
From: North Jersey
RE: octane?
H-D owners manuel says use 91 octane or higher. Why bother with lower grades? The MoCo knows best what octane rating should be used with their engines. If you are not getting any knocking or pinging I guess that's good, but maybe over the long haul you may be doing harm to the engine. For the few pennies difference between midgrade and premium I would not bother myself. Just my .02
Stellar HDF Member
Joined: Jan 2007
Posts: 2,626
Likes: 1,347
From:
RE: octane?
Much of what makes it into the owner's manual is there to protect the MoCo, not you and your machine. All other things being equal, you will get more horsepower andmore efficiency from a lower octane fuel, absent predetonation. Getting more power form higher octane is one of the most widely misunderstood concepts in modern machinery! If you are running high compression, high heat or other conditions that warrant high octane, then you are constrained. Unless I am at en event and know that I am going to begetting stuck in traffic with high ambient temperatures, I run regular and have had no problems whatsoever. I enjoy more power and lower operating costs. Recommending higher octane in lower compression engines is a safe way for the manufacturer to avoid problems with premature detonation.
The example posted above with higher mileage is not surprising at all - in fact, it is to be expected.
I have expressed whatI do on my bike. Don't try this at home - YMMV.
The example posted above with higher mileage is not surprising at all - in fact, it is to be expected.
I have expressed whatI do on my bike. Don't try this at home - YMMV.
Outstanding HDF Member
Joined: Apr 2006
Posts: 2,395
Likes: 25
From: St George, UT
RE: octane?
That is interesting stuff. My riding buddy switched from 91 to 89 octane in his Kawasaki Nomad, and his gas mileage has come up. He was getting just under 40 on 91 octane but is getting 41-42 on the 89. Hmmm!
Extreme HDF Member
Joined: Dec 2007
Posts: 13,402
Likes: 941
From: Illinois
RE: octane?
Yeap-more mpg,better starting with lower octane gas. Unless you'r drag racing higher octance is a big waste of $$$$$$$$$$$$$$$$.
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Road Warrior
Joined: Feb 2007
Posts: 1,730
Likes: 199
From: Vancouver BC
RE: octane?
ORIGINAL: Mac57
H-D owners manuel says use 91 octane or higher. Why bother with lower grades? The MoCo knows best what octane rating should be used with their engines. If you are not getting any knocking or pinging I guess that's good, but maybe over the long haul you may be doing harm to the engine. For the few pennies difference between midgrade and premium I would not bother myself. Just my .02
H-D owners manuel says use 91 octane or higher. Why bother with lower grades? The MoCo knows best what octane rating should be used with their engines. If you are not getting any knocking or pinging I guess that's good, but maybe over the long haul you may be doing harm to the engine. For the few pennies difference between midgrade and premium I would not bother myself. Just my .02
Ultimate HDF Member
Joined: Oct 2006
Posts: 6,095
Likes: 0
From: clearwater, fl
RE: octane?
what i heard on the tv theother night. is that the higher octane causes the enine to run cooler. how much who knows? as for the milage differances, is your bike ever consistant with say, 40 mpg everytime you fill it up? for me it depends on how i drive, traffic that week. it cant ever me consistant so to say that you put in 87 or 89 octane and it made a 1 to 2 mile differance. did it really make a differnance? exept in the wallet