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I usually put 91 octane in my bike, until today after reading this thread, i filled up with 89 octane. We'll see how she likes it. Thinking she'll be just fine with it.

Also for some reason i keep thinking for changing back to the Stock Air filter and try it, i have a K&N now.
I think it fits in its spot better than the K&N and i already have the Honda filter.
Might try it.
 

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I know this is an old thread but I saw someone looked at it recently. There may be some people out there who have been misguided as my dealer tried to misguide me many years ago when I bought my VTX 1300 new. So here goes.

I have written on this subject before. I know some of you will call BS on the following and swear your VTX runs 100 mph faster or is 10 seconds quicker in the quarter using 100+ super premium gasoline but please spare me and do the research.

Use what the owners manual states. The book states 87 or 86 use that. I don't care to go into all the theory or facts again but higher octane in a correctly running engine that designed to run on 87 pump octane, also officially called Anti Knock Index AKI, is a waste of money and no gain of performance or mileage unless maybe, maybe it is ethanol free.

I can't hold back, sorry.

It still can lead to the following issues:

The higher octane number means the detonation is delayed so therefore in our engines this means the fuel will not be completely burned thus leading to more carbon deposits which means eventually there may be enough carbon build up in the cylinder head to either cause pre ignition, bad for engine, and/or requiring the use of higher octane so as to lessen the pre ignition. Then it becomes a vicious cycle of carbon build up until the engine is wasted.

Yes there is an anti knock sensor on most engines so the timing is retarded so as to lessen the damage caused by pre ignition. Computer controlled vehicles can adjust for changes in octane to some extent.

Have you ever turned off the ignition on an engine but it continues to run? That is dieseling caused by pre ignition, meaning the fuel is being ignited before it should be ignited because of the hot carbon spots in the cylinders. Sometimes this is caused by a rich fuel mixture which still leads to carbon build up. Other times it is too much carbon. Many of today's engines have a fuel cut off to prevent any fuel entering the engine after the "key" is turned to the off position thus preventing this.

Because many Harleys are air cooled thus running at higher temps require premium because at higher temps there is a tendency of the fuel to ignite quicker (before the sweet spot of the stroke) so higher octane delays the explosion of the fuel/air mixture. Other vehicles require higher octane because they have higher compression ratio and/or different spark timing.

Our liquid cooled engines in proper working order run at a more constant temperature thus better control of emissions and better performance.

FYI: In the US and Canada the number on the pump is the Anti Knock Index number (also known as Pump Octane Number) which is equal to Motor Octane Number + Research Octane Number divided by 2. AKI=(R+M)/2. In Europe and a lot of other places it is the Research Octane Number on the pump which is always a higher number than the number we see in the US and Canada.

Octane can be raised by the use one of the alcohols but then we get into another problem, especially in small engines.

Also, the higher elevations do not require as high of an octane number. I just do not remember the rule for calculating it. I don't adjust my octane choice at elevation because I am usually not up there for more than a tank. If I lived there I'd check into the requirement. The same with the carb setting. Yes, it runs rich but for no more miles than I'll be putting on it at above 6000 feet it is not worth the trouble. I have ridden many times above 9,000 feet even 14,260 feet (Mt. Evans) with not problems.

A side note on brands: There is not much difference between brands (there are only a few refineries) except for the additives. I would recommend what they call Top Tier brands. Usually this is the major name brands. They tend to have more "cleaning" additives but more importantly with ethanol being used and misused it is the pureness of the fuel. More importantly, with the ethanol problem, use a station that sells a lot of gasoline so there is less chance of "fuel separation" and water absorption caused by the ethanol.
 

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I was recently having problems with my bike and decel pops and jerking. It was running real ruff. I called the dealer and they said I should just run 87 or 89 instead of the high octane I was running. I drained the tank, I had just filled up, and put some 87 in and it ran like a champ. I would have never believed that the gas octane could make that much of a difference. Do a search on octane and you will find some posts about the subject.
Same with me, I was getting a very frequent backfire. Almost every time I let off the throttle. Mine has a hypercharger intake and cobra pipes so the jets had to be tuned for the upgrades. I thought maybe it wasn’t right but It straightened out when I started using 87 instead of 93 and been fine since.
 

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Yes this is an old thread, but many new VTX owners/riders since this was initiated. Mechanically, my bike is stock and since 2004, I have always used regular 87 octane. Runs like a champ.

The best advice I can give is to ALWAYS keep up on your scheduled maintenance - replace worn hoses, clean you carb, adjust your valves and you and your bike will have a long & break-down free relationship.
 

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I always use 87 during the riding season. Then, around oct-nov. , I'll throw in no ethanol (91) for "storage". I normally drain all my small engines (trimmers, mowers, snowblowers). But, this way, i have the bike ready in case we get one of those stray "nice days" during the winter.
 

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My 2007 VTX 1300 runs great on 91 Octane ethanol free, so did my Yamaha Raider for the 93,000 Miles, that I owned it. ;)
 

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My 2007 VTX 1300 runs great on 91 Octane ethanol free, so did my Yamaha Raider for the 93,000 Miles, that I owned it. ;)
Does it not run well on 87?
 

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My 2007 VTX 1300 runs great on 91 Octane ethanol free, so did my Yamaha Raider for the 93,000 Miles, that I owned it. ;)
Never said it wouldn't run on the higher stuff. We only say it was DESIGNED TO RUN on the lowest octane available. Using anything more than the lowest just wastes money and in the 1800's causes plug fouling and carbon build-up
 

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Oh it runs fine on 87, I just chose not to use ethanol in my motorcycle/small engines. ;)
 
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We've had no choice but to use ethanol in Illinois for over 30 years now. Every octane level is 10%ethanol and all my cars, trucks, lawn mowers, snow throwers and weed eaters have survived without any problems. The only thing you have to do with it, is use a bit of fuel stabilizer before you store them for months. If you use Seafoam/Sta-Bil/Startron/etc... before you put your motorcycle away for the winter, it will be just fine in the spring
 

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We've had no choice but to use ethanol in Illinois for over 30 years now. Every octane level is 10%ethanol and all my cars, trucks, lawn mowers, snow throwers and weed eaters have survived without any problems. The only thing you have to do with it, is use a bit of fuel stabilizer before you store them for months. If you use Seafoam/Sta-Bil/Startron/etc... before you put your motorcycle away for the winter, it will be just fine in the spring
It’s almost seems like planning ahead will save you a lot of headaches in the long run. It’s magical.


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If you really want ethanol free. :unsure:

 
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