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Discussion Starter #1
I have 600 miles on my new 06 blue/silver 650 Strombucker. I have been filling her up with premium unleaded, but wondered what other people are using? Is there any noticeable performance difference with premium vs. regular unleaded? This bike is soooo cool. Thanks to all you Stromtroopers out there for all the great information on this site.
Tightlines :lol:
 

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Regular is more than enough. Anything above 87 octane is a waste of money.
 

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Without getting into the physics behind octane ratings etc. The simple explanation is this. Octane is a requirement of compression. The higher the compression pressure the higher the octane needed. Suzuki has built this engine with a compression pressure requiring regular gasoline. Unless you experience knocking or pinging just use what is called for. You will get less performance out of the premium fuel because it won't burn properly.
gbritnell
 

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Glad I ran across this post. I had always heard that Premium was needed because of the higher compression ratio, but maybe that is bogus info. I will do some more reading and then give it a try and see what the results are. Definitely would like to save .20 cents a gallon on my fuel bill!
 

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I said I wasn't going to drag this out but there needs to be a little more explanation about compression. The advertised compression of an engine is entirely different than the cylinder compression pressure. If you take 2 engines with a listed compression ratio of 11:1 and put different camshafts into them you will end up with different cylinder pressures. The explanation for this is camshafts determine when the valves open and close. If you want an engine to run better at a certain r.p.m. range you put in a different camshaft. How early (in the crank rotation position) it opens and how late it closes will determine how much pressure will build up in the cylinder so don't just look at the advertised ratio and say "well my buddy has a 4 cylinder bike and his compression is the same as mine and he has to use premium so therefore I have to use it also". Use what the manufacturer recommends. They built the engine, they would know better than anyone what gasoline it's supposed to burn.
gbritnell
 

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Gbritnell, nice post. Makes a lot of sense and now I have more for my knowledge base. Thank you.
 

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gbritnell said:
I said I wasn't going to drag this out but there needs to be a little more explanation about compression. The advertised compression of an engine is entirely different than the cylinder compression pressure. If you take 2 engines with a listed compression ratio of 11:1 and put different camshafts into them you will end up with different cylinder pressures. The explanation for this is camshafts determine when the valves open and close. If you want an engine to run better at a certain r.p.m. range you put in a different camshaft. How early (in the crank rotation position) it opens and how late it closes will determine how much pressure will build up in the cylinder so don't just look at the advertised ratio and say "well my buddy has a 4 cylinder bike and his compression is the same as mine and he has to use premium so therefore I have to use it also". Use what the manufacturer recommends. They built the engine, they would know better than anyone what gasoline it's supposed to burn.
gbritnell
This thread is definitely not for the mechanically declined folks! Yikes, this stuff makes Stromette's brain hurt! :oops: I just wanted to vote for REGULAR GAS. I ran mid-grade once b/c I was in nowhereville and they were out of regular. Can't say I noticed any difference. Why pay more when regular gets the job done?
 
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I have no scientific explaination, however my DL 1000 runs best on 87 octane. When I first got the bike, I ran premium and the bike had some issues. Just running 87 octane solved many of my problems.
 

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Higher octane fuel burns slower, effectively retarding the timing. The only engines that run well on different octanes are the ones with knock sensors. The sensor senses pinging and orders the computer to dynamically adjust the timing until the knock disappears. The owners manual will outline the octane parameters in that case. If the manual specifies a single grade, it's best to use it.
 

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Low compression

On top of all these technical statements also consider that if you are at any kind of altitude (6,000 feet here) there is also considerably less atmospheric pressure to start with and thinner air, so your final compression is probably less than at sea level. Of course you get less power too, but also better gas mileage because you need less gas to mix with less air. Overall your motor is not working as hard and will probably last longer. Kind of like the reverse of a supercharger. I think that is why there are so many old crappy cars out here that have disappeared from roads elsewhere, they don't rust, their engines are underworked, and the registration fees are a lot cheaper on an old worthless heap!

Well enough philosophy....I started running 87 (or is it 85?)and it works fine, I don't notice any difference. Same story for my ST1300.
 

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Watching you constantly refer to yourself in the 3rd person gives more than a few here a headache :roll:

STROMETTE said:
This thread is definitely not for the mechanically declined folks! Yikes, this stuff makes Stromette's brain hurt! :oops: I just wanted to vote for REGULAR GAS. I ran mid-grade once b/c I was in nowhereville and they were out of regular. Can't say I noticed any difference. Why pay more when regular gets the job done?
 

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Third person worked for Julius Caesar. It doesn't bother me. People loosing things when not referring to lowering they're/there torque value bothers me unless English is not their first language.
 
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Re: Altitude

Ajaxthedog89 said:
On top of all these technical statements also consider that if you are at any kind of altitude (6,000 feet here) there is also considerably less atmospheric pressure to start with and thinner air, so your final compression is probably less than at sea level. Of course you get less power too, but also better gas mileage because you need less gas to mix with less air. Overall your motor is not working as hard and will probably last longer. Kind of like the reverse of a supercharger. I think that is why there are so many old crappy cars out here that have disappeared from roads elsewhere, they don't rust, their engines are underworked, and the registration fees are a lot cheaper on an old worthless heap!

Well enough philosophy....I started running 87 (or is it 85?)and it works fine, I don't notice any difference. Same story for my ST1300.
The compression ratio doesn't change at altitude because it is a ratio of how much the cylinder is compressing the air inside compared to the un-compressed air which originally entered the cylinder. That's the same no matter what the altitude is.

You CAN use a less-rich mixture of gas at higher altitudes because there will be less oxygen inside the cylinder. However, this does not equate to better gas mileage. Like you said, "the motor is not working as hard" -- it's not generating as much power because there isn't as much oxygen to burn. Thus, you have to open the throttle more to go the same speed you would go at sea level. I guess there is less drag due to wind resistance, but I think the lack of oxygen in the mixture in the cylinder will have a larger effect.

The nice thing about the VStrom having fuel injection is that if the injection system is good, it should automatically reduce the richness of the fuel/air mixture at higher altitudes. On a carbureted motorcycle, you'd have to change the jetting. Anyone know if the VStrom's injection system does this?
 

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Re: Altitude

Remarksman said:
The nice thing about the VStrom having fuel injection is that if the injection system is good, it should automatically reduce the richness of the fuel/air mixture at higher altitudes. On a carbureted motorcycle, you'd have to change the jetting. Anyone know if the VStrom's injection system does this?
I would assume so as it has an ambient pressure sensor.

Generally good info in this thread. I'll add that there are a variety of factors determining the octane appetite of an engine, not just CR. In general, the factors that raise octane requirements are:

+ high CR
+ big cylinder bores
+ low RPM operation
+ lean mixtures
+ air-cooling
+ aggressive valve timing
+ carburetors rather than FI
+ operating at sea level rather than altitude
+ operating a large throttle openings at low revs
+ high ambient temps

Conversely octane requirements are lower for

+ low CR
+ small cylinders
+ high RPM operaiton
+ rich mixtures
+ liquid-cooling
+ mild valve timing
+ FI (which tends to be more precise and avoid "lean spots")
+ operating at atitude (which limits peak cylinder pressures)
+ small throttle openings
+ cool ambient temps

All these factors play into it. That's why a big air-cooled carb'd twin running 9:1 compression may need 93 octane (and ping at large throttle openings during hot weather) while a small high-revving 600c multi with 13.2:1 will run fine on 86 octane regular, never pinging.

Go with what the mfg suggests unless you have a strong reason to deviate (like the bike is pinging). The advice to run premium just because the CR is 12:1 (or some other arbitrary number) is completely bogus. The factory knows what they're talking about on this one.

- Mark
 

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greywolf said:
Third person worked for Julius Caesar. It doesn't bother me. People loosing things when not referring to lowering they're/there torque value bothers me unless English is not their first language.
Are they the same people that install steering dampners to help with hard breaking? Most of them probably don't wear helmuts, either.
 

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Re: Altitude

Remarksman said:
Ajaxthedog89 said:
On top of all these technical statements also consider that if you are at any kind of altitude (6,000 feet here) there is also considerably less atmospheric pressure to start with and thinner air, so your final compression is probably less than at sea level. Of course you get less power too, but also better gas mileage because you need less gas to mix with less air. Overall your motor is not working as hard and will probably last longer. Kind of like the reverse of a supercharger. I think that is why there are so many old crappy cars out here that have disappeared from roads elsewhere, they don't rust, their engines are underworked, and the registration fees are a lot cheaper on an old worthless heap!

Well enough philosophy....I started running 87 (or is it 85?)and it works fine, I don't notice any difference. Same story for my ST1300.
The compression ratio doesn't change at altitude because it is a ratio of how much the cylinder is compressing the air inside compared to the un-compressed air which originally entered the cylinder. That's the same no matter what the altitude is.

You CAN use a less-rich mixture of gas at higher altitudes because there will be less oxygen inside the cylinder. However, this does not equate to better gas mileage. Like you said, "the motor is not working as hard" -- it's not generating as much power because there isn't as much oxygen to burn. Thus, you have to open the throttle more to go the same speed you would go at sea level. I guess there is less drag due to wind resistance, but I think the lack of oxygen in the mixture in the cylinder will have a larger effect.

The nice thing about the VStrom having fuel injection is that if the injection system is good, it should automatically reduce the richness of the fuel/air mixture at higher altitudes. On a carbureted motorcycle, you'd have to change the jetting. Anyone know if the VStrom's injection system does this?

Not sure I buy this. If you have less oxygen you use less gas You also produce less power, but that does not necessarily equate to RPM. The computer system on the FI compensates and pumps less fuel into the mixture. I routinely get 52-53 mpg. What do you get at sea level? Less I expect, at least that is what I see from anecdotes of others. I have the same experince on my ST1300 also, higer mileage at higer altitude.
 
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