loose carbs?
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Gotta question, lets see if anyone has an idea. My bike is running kinda funny under 7,000. As soon as I hit around 7,000 it takes off and works normal. I asked a few bike people and mechanics and they think that my carbs might be loose and sucking in extra air. Other people think it might be something to do wiht the fuel system. Any ideas??
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Carbs work on two Jets, Main Jet and needle jet. One jet is for higher RPM's and the other is for lower RPM's. It sounds to me you are having a fuel problem with either your entire setup. What are you running for exhaust, intake, jetting? With carburation, everything has to be on the same page to work properly. Have you installed a jet kit?
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Roller28 wrote:
Carbs work on two Jets, Main Jet and needle jet. One jet is for higher RPM's and the other is for lower RPM's. It sounds to me you are having a fuel problem with either your entire setup. What are you running for exhaust, intake, jetting? With carburation, everything has to be on the same page to work properly. Have you installed a jet kit?everything is stock except for a KN filter and a Vance and Hines exhaust.
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Roller28 wrote:
yes octane levels, they call it grade of fuel such as 89, 90, etc..
Then I'm gonna have to disagree with you. For highest performance, I would go with a fuel such as VP MR9. It's 87 octane, but you'll prolly see a good 5-10 HP on a dyno with no fuelling changes. -
2wheeler wrote:
Then I'm gonna have to disagree with you. For highest performance, I would go with a fuel such as VP MR9. It's 87 octane, but you'll prolly see a good 5-10 HP on a dyno with no fuelling changes.How can you get 5-10 hp out of an 87 octane fuel? Explain...............................
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First of all, in a street bike you do not want to run straight race gas, you want to mix it 50/50. I have seen way to many engines take a crap because it can not hold up to that gas. GP bikes run this gas for a reason, because the engine can handle it. I still don't see someone getting 5-10 hp from the gas, do you realize how hard it is to squeeze more HP from these bikes, esecially a carburated one! If you are the average rider on the street, just run the top pump octane you can buy, otherwise you are wasting your money.
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Unfortuately, you're wrong. MR9 is highly oxygenated and that is how it makes power. As far as using it on street bikes, it is just fine. It will cause no damage. A friend of mine, Robert Jensen, who is the current F-USA road racing champoin in both the superbike and superstock classes uses it in his bikes. They are both limited to STOCK internals. His CR is raised to somewhere around 14:1 and he uses MR9(87 octane) in both, and they hold up fine. He sees around a 10 RWHP gain with that fuel.
As far as straight race gas, what fuel are you speaking of? VP makes over 30 different fuels alone.
And engines taking a crap from race gas? That one is new to me. The only bad thing about a fuel that I've seen is how Nutec will eat through fuel lines if not purged each day.
Oh yeah, and just this spring, Arcane Racing "squeezed" 701 HP from a Hayabusa. Stock was prolly 155-160. So, there's some room to move in the HP department.
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Ethan is right, and I gotta chime in here too. Fist off, high octane fuel doesn't make more power by itself, in fact since its harder to burn it may make less power. What high octane fuel does do it reduce knock. That is all the octane ratings really mean.
So, you're now probably asking why use high octane fuel if it doesn't add power? The answer is simple: It reduces knock which adds a layer of safety to an aggressive tune. For example, lets say that you can squeeze 200 whp out of a vehicle on pump gas w/ 18 psi of boost before knock, you should be able to run a bit leaner and/or turn up the boost and/or advance the timing if you run C16 which should in turn get you to a higher whp.
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Roller28 wrote:
First of all, in a street bike you do not want to run straight race gas, you want to mix it 50/50. I have seen way to many engines take a crap because it can not hold up to that gas. GP bikes run this gas for a reason, because the engine can handle it. I still don't see someone getting 5-10 hp from the gas, do you realize how hard it is to squeeze more HP from these bikes, esecially a carburated one! If you are the average rider on the street, just run the top pump octane you can buy, otherwise you are wasting your money.Funny guy... Word of advice. Dont argue with ethan about bikes, you wont win.
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what he said^^
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I guess I should not try to compete with you, since you are so knowledgeable about bikes, right? Whatever. This is not a competition what so ever, I was just trying to help someone out, and you took it way out of context. He has a jetting problem, not a fuel problem. And not to mention it is a carburated CBR 600, it is not ment for a speed demon, it is ment for riding. Come on people, quit trying to prove you are so knowledgeable, and enjoy the motorcycle for what it is ment for, RIDING! O, I forgot you can only ride 3 months out of the year there! This is not a pissing contest, I was just trying to help someone out. Come out here to California and ride with me sometime, then we will have a pissing contest!
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Roller28 wrote:
If you are the average rider on the street, just run the top pump octane you can buy, otherwise you are wasting your money.
In Roller28's defense, ^ how is this not true? It was my understanding that higher octane fuel was recommended for a bike like jct's.
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