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I always carry octane boost in my saddlebags for those times when I get some lousy off brand gas. It certainly helps reduce the pinging especially in hot weather (this is on a V2K)


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You don't really need any octane boost on a 900. Octane does not equal more power. In fact, these 900's usually run best with lower octane fuel, because the higher octane fuel burns slower and will often leave unburnt fuel in the exhaust.

But a good fuel injector cleaner won't hurt every now and then, although most name brand gas has it blended it. Seafoam is great, I use that occasionally. I use it every tank in the winter because it also stabilizes fuel, so if I end up not riding for a couple weeks because of the weather it's no biggie because it's got seafoam in there!
 

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Discussion Starter #5
Wow that's all pretty new to me! the manual calls for at least 91 octane are you saying it should be lower than that? kind of makes sense on the unburned fuel thing because everybody seems to have to Marble to get rid of the pop or backfire. I have just left mine as is cuz the occasional pop doesn't really bother me. Seafoam seems to be the preference so I have to give it a try. Do you have a 900? did you marble yours?

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Yeah, I didn't believe it either. After reading a few threads about people running 89 in their tanks, I tried it myself on both the 1600 and the 1700. Been through a tank so far, not a single problem.

I'll also say that the bike seems to actually run better. Now, this could be the same sort of 'Runs Better' that seems to occur right after I wash and wax the bike, but I take what I can get.
 

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FWIW, when octane booster says it "raises octane by 5 points" that means 87 goes to 87.5. Not much difference, but enough in some cases to keep the rattle at bay. Most of that stuff is pretty spendy though so if you need a little more octane then perhaps mixing a gallon of 91 into a tank of 87 would work. In 5 gallons of fuel, 4 gal of 87 and 1 gal of 91 equals 87.8 octane and probably costs $0.25-$0.50 to do it, rather than buying a bottle of octane boost.
 

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High octane fuel is recommended for new bike because EPA requires them to be set up so lean from the factory. Higher octane retards detonation, resulting in a slower burn and less heat. If you have aftermarket air/pipes, running high octane can make the bike run sluggish and cause carbon buildup, and reduce mileage. Switching from 91 to 87 in my bike gave me more power, faster acceleration and contributed to the mileage going from 37 MPG to 40-42.

One should run the lowest possible octane rating without getting constant pinging. Occasional pinging or knocking won't hurt anything, but as a constant it could.
 

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High octane fuel is recommended for new bike because EPA requires them to be set up so lean from the factory. Higher octane retards detonation, resulting in a slower burn and less heat. If you have aftermarket air/pipes, running high octane can make the bike run sluggish and cause carbon buildup, and reduce mileage. Switching from 91 to 87 in my bike gave me more power, faster acceleration and contributed to the mileage going from 37 MPG to 40-42.

One should run the lowest possible octane rating without getting constant pinging. Occasional pinging or knocking won't hurt anything, but as a constant it could.
Thanks for this explanation. I confess to never having heard pinging or knocking due to improper octane fuel. What am I listening for? Will it be obvious?
 

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Seafoam seems to be the preference so I have to give it a try. Do you have a 900? did you marble yours?
I did the marbling but used a wire cap instead and have had no problems and only pops a little when cold.

The only additive you need is the seafoam. I buy a can and use it thru at least 3 fill ups and it seems to really make a difference in sound and performance. I suggest using it every couple of months or so... really good stuff!
 

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Thanks for this explanation. I confess to never having heard pinging or knocking due to improper octane fuel. What am I listening for? Will it be obvious?
At the risk of sounding like a smart a$$, it sounds like pinging or knocking, literally.

If you have loud exhaust light pinging might be hard to hear, but the rattle/knocking of detonation is clear. Envision what it would sound like a small hammer beating on the top of a piston, or a cylinder with several large ball bearings bouncing around inside.
 

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Discussion Starter #12
Great information everyone, thanks a lot, definitely going to get the sea foam, and if I start scaring people on the side of the road with a backfire I'm going to do the marbling! Great information on the pain and what's needed, I'm getting 44 miles to a gallon right now running the higher octane. I will experiment.

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Wow that's all pretty new to me! the manual calls for at least 91 octane are you saying it should be lower than that? kind of makes sense on the unburned fuel thing because everybody seems to have to Marble to get rid of the pop or backfire. I have just left mine as is cuz the occasional pop doesn't really bother me. Seafoam seems to be the preference so I have to give it a try. Do you have a 900? did you marble yours?

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No I don't get any popping and I haven't marbled.

The manual actually does recommend 87. In Japan and other parts in the world, they use an octane index called RON. So it's recommending 91 RON. We use a different metric called RON+MON/2. 87R+M/2=91RON. So when it says 91, it's referring to the American equivalent of 87.

That's not every bike, or every Vulcan, but that is the 900. Believe it or not, the 900 does in fact recommend just regular gas, and seems to do well with it. Mine pops like crazy with premium. I used to always run premium because, like everyone else, I thought it was 'better' and I was putting 'more powerful' and 'cleaner' gas into my bike. As it turns out, I was doing the opposite. High octane gas definitely has it's use, but not in every machine. It's kinda like oil, straight 80 weight oil works awesome in the drive shaft of my wifes Honda Shadow, that does NOT mean it will work in the engine! Likewise high octane fuel will work great with engines tuned, timed, and designed differently, but the 900 has been designed to work with regular. Change the compression, stroke, ignition timing; maybe. But right now, it'll run best with regular.

Octane is (basically) a resistance to burning. Higher the octane, higher the resistance to burning. Add a turbocharger, make it run hotter, advance the ignition, then low octane fuel (which burns really easily and really fast) will ignite before it's supposed to. High octane fuel is needed. Stock, high octane fuel is harder to start and burns slower, so carbon builds up and it burns through the exhaust causing popping. Low octane fuel ignites quickly with the spark, produces clean power, and helps the bike run it's best!

That's not EVERY bike, but it is the 900. Big high compression air-cooled twins need high octane fuel. More heat, more compression, you need high octane to prevent the fuel from igniting too soon. But our 900 is not a big, high compression, air cooled twin!
 

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At the risk of sounding like a smart a$$, it sounds like pinging or knocking, literally.

If you have loud exhaust light pinging might be hard to hear, but the rattle/knocking of detonation is clear. Envision what it would sound like a small hammer beating on the top of a piston, or a cylinder with several large ball bearings bouncing around inside.

No, not at all. I appreciate your description.
 

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Discussion Starter #15
Wow! great stuff! less premium would be easier on a pocket book 2, I'm starting to like this bike more and more, I'll keep an ear out for pinging, engine knock, you ever get any of that?

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Discussion Starter #16
Okay I finally broke down and marbled. took out for a ride , still getting the pop I am definitely going to try the lower octane fuel. I am now wondering if everybody is marbling and capping, when in reality it is the fuel that's the problem.

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Marbling may still be necessary, as the way these bikes are built, the reed valves still put unburned fuel back into the exhaust headers.
 

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Theoretically, the valves are shoving the exhaust out the port before it has fully ignited. As to the slow burn issue, just about every site that explains the difference between regular and premium makes the claim that premium ignites more slowly.

A hot fire burning fuel quickly produces little soot. A smouldering fire burning slowly produces a lot of it. I imagine the same principle works in engines- the faster and hotter the burn, the less soot it produces. True or not? beats me. I just know the bike runs way better on regular than on premium.
 
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