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Unless you plan on doing some motor work or adding a full system, why bother? Are you having any issues with the bike?
 

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That’s Mister Chalet To You ....
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How much does a pull cost in the UK? I Can see the appeal from a pure curiosity standpoint but it's not going to be a big number anyway. Unless you've done some work to expect a big number or you're getting a custom tune, I'd throw that money at something useful.



But that's me.
 

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Captain Obvious ... because obviously it’s obvious
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A dyno is used as a tuning device. If you're not tuning it and not trying to figure out your AFR, you're wasting money.
 

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Discussion Starter #6
Ok boys thanks for the input.

No the engine has not had any work and nothing more than the pipe. I was thinking of a power commander but she’s got just under 30,000 miles on the clock and wasn’t sure if raising the bhp is a good idea?
 

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Discussion Starter #8
@ Spike52 she’s not happy on steady throttle mate and wondered if the KnN and pipe might have affected something to make it sort of judder and stutter. I did the plugs and that made it a bit better but not much
 

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Captain Obvious ... because obviously it’s obvious
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@ Spike52 she’s not happy on steady throttle mate and wondered if the KnN and pipe might have affected something to make it sort of judder and stutter. I did the plugs and that made it a bit better but not much
K&N is pretty shitty, honestly. The stock air filter is much better.
 

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That’s Mister Chalet To You ....
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K&N is pretty shitty, honestly. The stock air filter is much better.

Define 'better'. I've always found the concept of high performance air filters a little backwards. A filter is basically some material with holes to allow air to pass through but the holes are small enough to prevent dust & debris from entering the engine.


  • The 'better' the filter, the less crap it lets in but that means it's more restrictive and also less air gets in.
  • So 'high performance' means it lets more air in and as such, more crap in too, which means it's actually a worse filter than stock.

Stock is better.
 

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Captain Obvious ... because obviously it’s obvious
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Define 'better'. I've always found the concept of high performance air filters a little backwards. A filter is basically some material with holes to allow air to pass through but the holes are small enough to prevent dust & debris from entering the engine.


  • The 'better' the filter, the less crap it lets in but that means it's more restrictive and also less air gets in.
  • So 'high performance' means it lets more air in and as such, more crap in too, which means it's actually a worse filter than stock.

Stock is better.
There are a few caveats to what you're saying, because in the case of the comparison we have two different concepts that use different materials to meet these concepts. The stock filter is paper and is a one-time-use device, whereas the K&N and BMC both are reusable filters that use a different filtering media that can stand up to being washed and oiled. I don't have an objective data on the filtration rates of both filters, but we do know that the K&N use a cloth filter. We have also seen dynos that showed that the regular K&N actually makes less power, which means it's more restrictive than stock. This might mean better filtration, but it may be a simple byproduct of how the air flows through. We also know that there are race filters, which are meant for racing only, and these make more power by lowering the filtration media content. These are also reusable.
For me, the stock filter is the happy medium for me: it was designed to work specifically with the bike, it will filter well enough, and it gave me a better drivability feeling along with more power than the K&N. And I'm not going to run a race filter on a street bike for the bragging rights of 1-2whp.
 

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Hand-Eye Coordinator
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We have also seen dynos that showed that the regular K&N actually makes less power, which means it's more restrictive than stock. This might mean better filtration, but it may be a simple byproduct of how the air flows through.
Power is not necessarily down to how restrictive a filter is. Moving more or less volume is also not an indicator.

Maybe all the filters are capable of flowing more air than the engine requires at any time. This would be a logical assumption. Yes, the OEM may be the slowest flow, but there is more to it.

The faster air moves, the less pressure there is behind it. Less force to fill the cylinder (Bernoulli's principle). This now changes cylinder intake swirl and tumble. It may also change the absolute highest air pressure achieved on the intake, and so less air for combustion.

More pressure than designed for (so slower air) will also change the things mentioned.

I'm not a tuner, nor a mechanical engineer, nor do I have the specs, but simply removing air flow restriction does not equal more power. More power comes from more fuel and the right balance of air to completely combust the fuel.
 

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That’s Mister Chalet To You ....
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Hmm, and I always assumed the K&N = more hp = more air = less restrictive


Wrong on all counts :suicide
 

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Power is not necessarily down to how restrictive a filter is. Moving more or less volume is also not an indicator.

Maybe all the filters are capable of flowing more air than the engine requires at any time. This would be a logical assumption. Yes, the OEM may be the slowest flow, but there is more to it.

The faster air moves, the less pressure there is behind it. Less force to fill the cylinder (Bernoulli's principle). This now changes cylinder intake swirl and tumble. It may also change the absolute highest air pressure achieved on the intake, and so less air for combustion.

More pressure than designed for (so slower air) will also change the things mentioned.

I'm not a tuner, nor a mechanical engineer, nor do I have the specs, but simply removing air flow restriction does not equal more power. More power comes from more fuel and the right balance of air to completely combust the fuel.
You bring to light some very interesting points, thank you!
 

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That’s Mister Chalet To You ....
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...... More power comes from more fuel and the right balance of air to completely combust the fuel.
I had to google Bernoulli's principle and had no clue about pressure and velocity being inversely proportional. I'm trying to correlate how it affects 'performance' in an NA application. EDIT: you explained it. Maybe I should push Miller time out to 5:00 :facepalm


In any forced induction application, I don't think the principle comes into play because you're just mechanically stuffing-in more air. Regardless, one of the first things you do is upgrade injectors to try to keep up with the air being stuffed in. I think of engines as big air pumps.

But yeah, even back in '83, suzuki was bragging about their TSCC* engines, even in their radio jingle. Messing with the resistance of incoming air will obviously have an effect on that.






*twin swirl combustion chambers, for the young 'uns
 

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Power is not necessarily down to how restrictive a filter is. Moving more or less volume is also not an indicator.

Maybe all the filters are capable of flowing more air than the engine requires at any time. This would be a logical assumption. Yes, the OEM may be the slowest flow, but there is more to it.

The faster air moves, the less pressure there is behind it. Less force to fill the cylinder (Bernoulli's principle). This now changes cylinder intake swirl and tumble. It may also change the absolute highest air pressure achieved on the intake, and so less air for combustion.

More pressure than designed for (so slower air) will also change the things mentioned.

I'm not a tuner, nor a mechanical engineer, nor do I have the specs, but simply removing air flow restriction does not equal more power. More power comes from more fuel and the right balance of air to completely combust the fuel.

Hmmm... I try to imagine it and I am convinced smaller holes will raise the pressure in front of the filter but I am not that convinced it will give a higher pressure past it :gaah
 
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