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Offline cadler

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what octane gas?
« on: January 11, 2006, 02:12:59 AM »
What is the lowest octane gas you can use in your cb750's?
Thanks
Craig
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Offline Bob Wessner

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Re: what octane gas?
« Reply #1 on: January 11, 2006, 02:20:40 AM »
Assuming stock engine, regular, 87 US octane is the recommended fuel.
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Offline cbjunkie

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Re: what octane gas?
« Reply #2 on: January 11, 2006, 02:21:14 AM »
this topic has been flogged over and over - try a search and let the fun begin...


insomnia, bob?
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Offline TwoTired

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Re: what octane gas?
« Reply #3 on: January 11, 2006, 02:24:02 AM »
Depends on the country, as octane ratings may be different.  But, if you have a stock bike, Honda made them to run on regular fuel.  The owners manual for the 77 CB750F says 86 octane or higher pump octane and 91 or higher for RON ratings.   Current US ratings for regular are about 87 octane (average of RON and MON ratings).  

Cheers,
« Last Edit: January 11, 2006, 02:29:48 AM by TwoTired »
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Offline Bob Wessner

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Re: what octane gas?
« Reply #4 on: January 11, 2006, 02:24:44 AM »
No, just an aged basset hound. Her hours are my hours.  ;D
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Offline SteveD CB500F

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Re: what octane gas?
« Reply #5 on: January 11, 2006, 05:06:54 AM »
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Offline Gordon

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Re: what octane gas?
« Reply #6 on: January 11, 2006, 07:00:15 AM »
Quote from: cbjunkie on January 11, 2006, 02:21:14 AM
this topic has been flogged over and over - try a search and let the fun begin...


Yeah, let's not bring this one up again.  It's likely to get more heated than a "what oil should I use" thread. :o
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Offline Jonesy

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Re: what octane gas?
« Reply #7 on: January 11, 2006, 07:11:27 AM »
What I found out was the main source of confusion is the owner's manuals. If you look in ones printed before the U.S. (R+M)/2 rating system was adopted, they say one thing. Ones printed afterward say another. The change occurred somewhere between 1973-'74.
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Offline 78 k550

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Re: what octane gas?
« Reply #8 on: January 11, 2006, 07:15:57 AM »
I run 87 in my bike's.
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Offline Gordon

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Re: what octane gas?
« Reply #9 on: January 11, 2006, 07:20:53 AM »
Quote from: Jonesy on January 11, 2006, 07:11:27 AM
What I found out was the main source of confusion is the owner's manuals. If you look in ones printed before the U.S. (R+M)/2 rating system was adopted, they say one thing. Ones printed afterward say another. The change occurred somewhere between 1973-'74.

Had that same problem with my '74 VW van back when I was just a young pup and didn't know any better.  The info plate on the engine said to use 91 or higher octane fuel, so that's what I used for the first four years.  I was kind of pissed when I realized I had been wasting my money and that 87 was the current equivallent! >:(   Then again, that was back when a gallon of premium was going for half what a gallon of regular costs today.  Those were the days! ::)
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eldar

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Re: what octane gas?
« Reply #10 on: January 11, 2006, 07:30:17 AM »
87 works fince if you have a standard engine. What I would like to have a definative answer for is what octane to use if you have an 836 kit.
Do you need premium or can you use the midgrade? Midgrade is 89 - 90 octane.
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Offline ProTeal55

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Re: what octane gas?
« Reply #11 on: January 11, 2006, 07:41:55 AM »
My stock bike runs no different on 93 as it does on 87.
If the bike doesnt have more compression , their is no need to run a higher octane fuel.
My last racecar ran on 116  ;D
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eldar

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Re: what octane gas?
« Reply #12 on: January 11, 2006, 07:49:01 AM »
The standard 836 raises the comp to about 10.25:1 or so.
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Offline dusterdude

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Re: what octane gas?
« Reply #13 on: January 11, 2006, 10:02:18 AM »
eldy,try 89.the aluminum head will let you run higher compression without raising your octane requirements,however with an air cooled engine you may have to go up to 89 or maybe 93 or so.
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