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I bought my '04 650 custom about 3 months ago. Since owning I have been using 91-93 octane gas in it. Last week I put in 87 in it. Since then I noticed the engine running different. I have aggressive custom exhaust, and it seems to have really quieted down. WHen down shifting before I would get a few pops. After the 87, I'm getting nothing. Which I'm not complaining about that. It just seems after the 87 gas it's a different bike. I'm not to sure what to think about it. Or maybe the gas has nothing to do with any of it. Maybe something totally different is wrong.

Any comments?

Thanks

Caleb
 

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There are a lot of believer and realistic. Some like high octane and believe that our bike would run better with 91-93 octane gas but our bike is built to use with 87 octane, it even say in manual. From what I've read on internet, the high octane is not necessary a good thing for our bike and can create carbon build up from slow burning of high octane, thus you'd hear some popping sound more than that you might also see low mileage per gallon as well. Using 87 help the bike to run cleaner and proper burning also help your wallet as well as economic. To use whatever is your preference but as you can see you gain no benefit from running with high octane.
 

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Higher octane will increase performance and MPG.

I have run from 87 all the way up to 102 (you should only use above 102 if you have a high compression ratio like 12 to 1)

On 87 I get about 47 mpg, 91 gets me around the 53 mpg area and 100 easily gets 57 mpg.

You gain about 10-15% in power/performance going up to 102 octane but be prepared to pay around 9.00 a gallon for that gain in mileage and performance.

I can't speak of gas prices in your area but here in Southern California 91 octane goes for about 3.20 a gallon and seems to be the best trade off for performance and MPG for the price.

in answer to the above statement. Higher octane does not increase carbon build up, the opposed is true you have a hotter faster burning fuel the higher octane you go with less carbon build up and a more powerful efficient burn.
 

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That sticker on the frame tells me that mine should use 91 min. Still I use87. I think I will need to talk to the tech about that next time.

The related question I want to ask, is if the bike runs smoother on 91 or up.
Not that it matters but I have drag exhaust, and performance intakes; that I know nothing about since they were there from the beggining.
 

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Irregardless of what the sticker says Yamaha is a smart company. They know that not everyone will put in the recommended octane so their bikes are built to handle lower octanes. If all it took was going from 91 to 87 to damage our bikes I wouldn't own one.
 

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Fuel

The owners manual for an 04 V Star 650 says. your engine was designed to use regular unleaded gasoline with a pump octain number [(R=M)/2] of 86 or higher. A research number of 91 or higher.

Don't know what the research octain thing is but you use regular unleaded fuel.

Dave
 

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When I bought my 2003 650, the dealer said use the highest octane fuel in it, don't use the mixed stuff. The highest octane up here doesn't contain ethanol but the mid and low grades do.
 

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Be weary of anybody that tells you an engine designed to run off 87 will make more power and get better fuel mileage with a higher octane fuel. It just isn't true
 

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premium for me

I just got my V STAR 1100 today so I dont know what type of gas the previous owner used, but tomorrow I will be going to the pumps to put in the good stuff, priemium. My last bike was a 1986 750 maxim X and I know what a huge difference 91 octane made with that bike. Lets face it folks, these bikes only hold 3 or 4 gallons of gas, if the price of 91 octane is too much to afford then maybe its time to get a pedal bike !!
 
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I just got my V STAR 1100 today so I dont know what type of gas the previous owner used, but tomorrow I will be going to the pumps to put in the good stuff, priemium. My last bike was a 1986 750 maxim X and I know what a huge difference 91 octane made with that bike. Lets face it folks, these bikes only hold 3 or 4 gallons of gas, if the price of 91 octane is too much to afford then maybe its time to get a pedal bike !!
91 octane will likely hurt your bike more than help it.
 

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Actually these engines don't develop the cylinder pressures requiring "premium" gas. The Octane number refers to a fuel blends resistance to pressure ignition. All Fuels are a blend of differing carbon chain molecules. Octane is just an eight carbon chain molecule which is used as a standard to measure by. You want your engine as close to as possible to pinging (pre-ignition) for best performance/mileage. Use the 87 octane your engine your engine was designed for, but buy a better grade of gas. Stay away from the cheap stuff (No-name Big-Box store) and buy a good grade fuel (Texaco, Chevron, Mobil/Exxon, Shell) to name a few.
 

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Actually these engines don't develop the cylinder pressures requiring "premium" gas. The Octane number refers to a fuel blends resistance to pressure ignition. All Fuels are a blend of differing carbon chain molecules. Octane is just an eight carbon chain molecule which is used as a standard to measure by. You want your engine as close to as possible to pinging (pre-ignition) for best performance/mileage. Use the 87 octane your engine your engine was designed for, but buy a better grade of gas. Stay away from the cheap stuff (No-name Big-Box store) and buy a good grade fuel (Texaco, Chevron, Mobil/Exxon, Shell) to name a few.
http://www.toptiergas.com/retailers.html

Actually, you'd be surprised to see some of the names in this list:

QuikTrip
Chevron
Texaco
MFA Oil Co.
Conoco
Phillips 66
76
Entec Stations
Shell
The Somerset Refinery, Inc.
Kwik Trip / Kwik Star
Aloha Petroleum
Tri-Par Oil Co.
Turkey Hill Minit Markets
Mileage Stations
Road Ranger
CountryMark
Chevron Canada
Shell Canada
Petro-Canada
Sunoco Canada
 

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Out of the list - Conoco is the only one we have in Bismarck which is supplied from different vendors (like Tessoro or Cenex), depending on who they contract with. Now with mid grade at $3 a gallon (as of 4/6/10), I won't have a problem paying the extra 20 cents for premium. Will take my chances since I don't really like the 10% ethanol.
 

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I just got my V STAR 1100 today so I dont know what type of gas the previous owner used, but tomorrow I will be going to the pumps to put in the good stuff, priemium. My last bike was a 1986 750 maxim X and I know what a huge difference 91 octane made with that bike. Lets face it folks, these bikes only hold 3 or 4 gallons of gas, if the price of 91 octane is too much to afford then maybe its time to get a pedal bike !!
Hi Test burns slower, hence less power
 

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I usually get my gas at QuikTrip, because it is top tier and its priced right convenience works for me. Use premium in my truck (supercharged) and SeaDoo (high compression shaved head) because they require it. I'm not opposed to spending it if it needs doin.
 
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