Air filter opinions pleeze!

[EVLXX]

Eric,

You sure about that logic in re the K&N flowing more air?

Assuming the bike is a bit rich.  It will get richer at higer elevations and likely run worse.  If it is running worse with the K&N installed as well and gets better with the stock filter in place the K&N would be suspect of richening the mixture as well which means less air not more.  More air would tend to lean it out and should have improved the situation.

What I think poor Involute, who has by now gone out and bought an EFI bike, encountered is a mis tuned motor, already too rich and and over oiled K&N which presented further flow restriction and thus made the rich condition worse.

Proper steps for correction, as have already been pointed to, begin with getting the jetting right at baseline altitude.  If the bike is jetted for sea level it most certainly will be too rich at 4500 feet.  Heading uphill from there is bound to make it worse.

In the sentence I bolded out of your comments...

This was what I though last week as well.... well it's wrong...

More air ....means alot more fuel.

I used to think that more air meant a Leaner mixture, and it does in terms of a ratio, but it doesn't when you talking about the amount of fuel that gets picked-up as the air is flowing through a carberator.

I had to go back and re-study carburation again... in order to correct myself. :wink:

Still having problems with the slow air jet as well... I have one reference that says the air picks up the fuel and if you increase the jet size it'll pick up more fuel. And yet I have another reference that is saying just the oposite, that a bigger jet means more air in the mixture. :? I'll figure it out.

So... up to this point, I've got...

Higher altitude = less oxygen = richer mixture = which means you have to LEAN it out a bit.

A free'r flowing filter = more total air flow = richer mixture = which means you need to LEAN it out even more.

10 to 1 is the Rich run limit.

18 to 1 is the Lean run limit.

Hope that helps.

Hope that helps.

[pug]

Still having problems with the slow air jet as well... I have one reference that says the air picks up the fuel and if you increase the jet size it'll pick up more fuel. And yet I have another reference that is saying just the oposite, that a bigger jet means more air in the mixture. :?  I'll figure it out.

So... up to this point, I've got...

Higher altitude = less oxygen = richer mixture = which means you have to LEAN it out a bit.

A free'r flowing filter = more total air flow = richer mixture = which means you need to LEAN it out even more.

10 to 1 is the Rich run limit.

18 to 1 is the Lean run limit.

Hope that helps.

Hope that helps.

It would be nice to give us your references.

You know except fuel jets, there are air jets as well. When you go bigger with those, you go leaner. Everything else you're writing , simply just not makes sense.

Regarding the rich-lean ratios you provide, during startup some engines might go even richer, but under normal running conditions, 18 to 1 is good only for diesels or direct injection petrol engines.

[shovelstrokeed]

Eric,

I understand your point. Increasing air flow through a venturii wil increase the pressure drop with a consequent increase in the vacuum signal and more fuel sucked through the jet. BUT. We are talking about a flow increase of less than 1% at the max flow of the filter. 1% richer or leaner isn't gonna mean much. OK, you might go from stochiometry (14.7:1 AF ratio) up to 16:1 or so. Or down if the filter was more restrictive to say 12.9:1. Point is, the motor will still run, pull near red line in the gears, etc. as you are basically only going between best power and best economy settings.

As to the slow jet thing, it depends on the construction of the carb. Some use an air bleed to mix air into the fuel being pulled in by the venturii and those will lean the mixture as the jet size increases. Some will use a conventional jet that controls fuel flow directly and then things richen as the mixture increases. You really need to obtain a carb manual specific to your carb mfg/model and look at the flow diagram presented therin.

BTW, nice explanation of basic carb action.

[EVLXX]

It would be nice to give us your references.

You know except fuel jets, there are air jets as well. When you go bigger with those, you go leaner. Everything else you're writing , simply just not makes sense.

Regarding the rich-lean ratios you provide, during startup some engines might go even richer, but under normal running conditions, 18 to 1 is good only for diesels or direct injection petrol engines.

Current Reference = Sportbike Performance Handbook by Kevin Cameron

and old class notes from school

Choke mixtures maybe as rich as 4 or 6 to 1.... until the cylinder heats up, then rich run limit is said to be around 10 to 1.

And alot of internet research... also found me reading that alot of your new cars do run at 17 and 18 to 1 while cruising... to get better gas mileage.

[EVLXX]

Eric,

I understand your point.  Increasing air flow through a venturii wil increase the pressure drop with a consequent increase in the vacuum signal and more fuel sucked through the jet.  BUT.  We are talking about a flow increase of less than 1% at the max flow of the filter.  1% richer or leaner isn't gonna mean much.  OK, you might go from stochiometry (14.7:1 AF ratio) up to 16:1 or so.  Or down if the filter was more restrictive to say 12.9:1.  Point is, the motor will still run, pull near red line in the gears, etc. as you are basically only going between best power and best economy settings.

As to the slow jet thing, it depends on the construction of the carb.  Some use an air bleed to mix air into the fuel being pulled in by the venturii and those will lean the mixture as the jet size increases.  Some will use a conventional jet that controls fuel flow directly and then things richen as the mixture increases.  You really need to obtain a carb manual specific to your carb mfg/model and look at the flow diagram presented therin.

BTW, nice explanation of basic carb action.

Well, I'm still a little confused on your AFR sentence there, because I keep reading it and getting that you are trying to say that if I increase the flow... it'll go leaner. :?

But, besides all that... You might find it interesting to know that I have done alot of testing with a DynoJet WidebandCommander, and that the stock mapping has the bike running down in the 12 to 1 ratios under hard aceleration.

So climbing up to 5K feet and slapping in a K&N, could easily put you into a rich 10 or 11 to 1 ratio. And I have noticed that every time I see the needle on my guage drop into the 11's or even the 10's, she'll start to bog down a bit.

[Dion]

I stand by my earlier statement.

Put your money into upgrading your brakes and suspension

[matey_peeps]

On most every bike forum on the 'net, the discussion of stock vs reusable air filters has gone the way of discussing the best oil, the best tires, the best chain lube, etc, etc. This debate is as never-ending as it is pointless.

That being said, I'll offer up my non-dynoed, anecdotal, actual real-world experience having used the K&N on my Blackbird for just shy of 6 years/75,000 miles: it works just fine.

And I've never had to buy the spendy paper air-flter once, not  since I rolled the bike off the showroom floor.

I use the K&N for strictly for the maintenance longevity aspect, vice any perceived/actual performance gains.

Maybe we need a 'Never-Ending Pointless Recurring Threads' section like the FJR board? I'd get behind that idea.

[EVLXX]

Maybe we need a 'Never-Ending Pointless Recurring Threads' section like the FJR board?  I'd get behind that idea.

:fuckofftroll:

Well... for some of you, I know it's all fine and dandy to say "Just ride" and "who gives a fuck about gas mileage". And That Fine... for YOU.

(Although I think it's funny when poeple say they don't care about gas mileage... yet they complian about gas prices.)

But not me!

I like to understand what's going on in with my motor, and if at all possible want to Learn more.

And in this particular topic... I have learned some more. And... I'll add I enjoy sharing my understandings with others. sometimes I can help them, and sometimes they help me.

And we get alot of new poeple here every day (probably because it's the best damn Board there is, in my opinion).... so maybe it's old hat to you, but it's new to others, and I like listening to the enthusism, even if it is the second third or.... tenth go around.

So... if you don't want to read the topic... don't open it. :wink: Works for me.

If that doesn't work.... maybe you should just stick to the FJR board or Maybe the ST.N

...

Sorry, if I sound a little harsh there, your comment kinda rubbed me the wrong way like censorism, but... did you ever consider that Learning is a never ending and reacurring thing.

And that doing a search is often a big pain in the ass... because it often pulls up pages and pages of shit that doesn't pertain to shit. So have to wade through all the garbage to find some usefull info... tends to lead me to start the topic over again. It's just easier..... for those that are willing to participate.

Actually... it would help, if the Important and usefull thread area.... had more important and usefull threads. :wink: For instance there was a great Oil topic back in 2003.... but it's a bitch to find now.

OK... done venting...

Have a good day. Troll!

[shovelstrokeed]

Eric,

I've been playing with this stuff a long time as well. The only bike I still own that has carbs on it, discounting my '48 Panhead, is my '91 Guzzi. I have to keep that thing way rich to stay out of detonation with it.

12:1 is pretty well where you want to be under hard acceleration. Yeah, your gonna have to compensate for altitude with jetting, hence the transition into the 11's at altitude.

The point that might be throwing you off a bit, and you are not really off all that much, is that even with the increased flow, the air is not as dense, hence less O2 and a richer mixture. The carbs do compensate a bit for this or none of us would be able to climb hills. I would even say that your experience is right in line with theory and principles of operation.

If you were to monitor manifold pressure you will find that you are also producing less vacuum at altitude and that is why there is less compensation in the venturii signal. It is only when you convert CFM to SCFM that you start to see the effects of density/altitude on your mixture. It can be crazy making for those who live in mountinous areas. With carbs, you are kinda on the horns of dilemma. Get jetted right for 2500 feet and go for a nice ride in the mountains and your gonna be fat at 8000, no doubt. Your gonna suffer a power loss of 1% for every 1000 meters and that will be compounded by an over rich condition. Probably the best compromise would be to jet for a 4000 foot density-altitude, try to do it on a 70 degree day and accept that you'll be a bit lean at sea level under power and a bit rich at 8000 feet.

You can fight Burnolli, Hooke and Charles all you want but they will always win in the end.

[EVLXX]

Thanks Shovel...

I see where you're going now.

I have a 92 CR500R that I've been haveing some troubles tuning the Pilot jet on. It runs fine at 6K feet, and is OK to start with at 8K feet, but after 1/2 a days ride in the mountians she doesn't want to idle as well... or start again if I kill it.

I still must be to Rich for that elevation... now the question is which way to go with the Pilot jet. I don't know if it a Air jet or a Fuel jet.

I'll have to do some digging on that, maybe I've been going the wrong way. Or maybe I just need to go farther consisdering the elevation.

You can fight Burnolli, Hooke and Charles all you want but they will always win in the end.

I know... but it's fun trying.

Now on another note.... I wonder if I can figure out a way to see if I'm getting any detonations on my bird, when I'm running those crazy lean ratios at the lower R's. The last thing I want to do is hurt my motor. I haven't heard any predetonations yet... but then again, I don't know if I could.

[matey_peeps]

For the record, excluding people from a discussion because they disagree with you is censorship, or 'censorism' as you called it.

Back to the topic: I have used K&N filters on the bird and on other bikes, and because I have experienced a loss of fuel economy, I will go back with the stocker in the spring. This is based on my observations, and I don't understand how any amount of pointless internet hand-wringing is going to add anything to the knowledge base.

To sum it up: my fuel economy has gone down since I put in a K&N. I'm going to go back to stock and see what happens. Update to follow.

[EVLXX]

Well Matey, you said it...

To sum it up: my fuel economy has gone down since I put in a K&N. I'm going to go back to stock and see what happens. Update to follow.

That would prove that you're running Richer... from more air flow. And yes... the simple fix would be to put the stocker back in it.

Although if it were Me... I'ld tune it, so that I would have to buy anymore airfilters.

As for the piontless hand wringing... well over the corse of this topic I have learned a few things... so to me... it wasn't pointless. :wink:

As for the censorism... I wasn't trying to exclude....

Oh nevermind.

It's water under the bridge.

[shovelstrokeed]

I have not seen the XX carbs to comment but a general rule of thumb is that if the idle mixture adjusting screws are on the engine side of the slides, then they are air bleeds. That means a larger pilot jet will lean the mixture. On the air cleaner side and it's a fuel jet and the mixture will richen.

I'm going way back to my Amal tuning days here but it really sounds to me like jetting won't get you the solution here. I really think you need a richer, read smaller, slide cutaway. You could try raising the needles one notch or a half notch if you can find the right washers.

That would, the slide thing, along with a main jet change, fix the too rich on large throttle openings and too lean on the small ones. That's the thing about carbs and their multiplicity of interacting circuits and parts. They can be a real PITA to get right. The guys who can do it are real wizards.

I wouldn't worry over much about detonation at light loads. Even way lean, unless the motor is called upon to produce sudden acceleration you should be OK. You have an accelerator pump circuit to take care of that very thing so again, little to worry about. I would try to keep the motor out of the 3K RPM range (higher is better). That lever under your left toe is your friend there. :wink:

[Redbird]

Just so we all know how far into the woods we are here, some of the people here are refering to FI bikes (Eric's bike is FI, for one) and people are responding under the assumtion that we're all still talking carbs.

FI and carbs are two totally different discussions, but they've become intertwined here in a really messed up way. This thread will only become more confusing from here on out.

Have fun with it :wink:

[matey_peeps]

Oh ya, mine's a 99 BTW.

[shovelstrokeed]

Just so we all know how far into the woods we are here, some of the people here are refering to FI bikes (Eric's bike is FI, for one) and people are responding under the assumtion that we're all still talking carbs.

FI and carbs are two totally different discussions, but they've become intertwined here in a really messed up way. This thread will only become more confusing from here on out.

Have fun with it :wink:

ROTFLMAO!! Here I thought it was carbs all the time. Whole new ball game.

Something mighty wrong then with either the MAP sensor, if there is one, or the barometric pressure sensor. The thing should compensate for altitude with no problems. A look at the fuel pressure regulator and its output might be beneficial as well.

I will stand by my recommendation for a carbed bike from the symtoms described.

[EVLXX]

yep...

this thread is to fuckerd-up...

Shovel... sound like you've got some good shit spinning around in that head of yours. So I'll PM you with any further ideas.

But I have to agree with Tim here...

but they've become intertwined here in a really messed up way. This thread will only become more confusing from here on out.

Have fun with it :wink:

Plus.... I think my stick broke, and the horse don't give a shit any more cause it was dead a long time ago.

[shovelstrokeed]

Butterflies and slides and jets and MAP sensors, OH MY!

What was the original topic anyway?

I think I'll turn the electric blanket up a bit tonight. Maybe my leg will shrink back down to its original size.

[EVLXX]

He he... that's funny Shovel...

Yes I'm a little F'd up in the head on this shit as well.

But so far I figure I'm saving about a gallon of gas per tankful... so to me, it's worth it.

You have a PM.

[pug]

I have not seen the XX carbs to comment but a general rule of thumb is that if the idle mixture adjusting screws are on the engine side of the slides, then they are air bleeds.  That means a larger pilot jet will lean the mixture.  On the air cleaner side and it's a fuel jet and the mixture will richen.

I think you've got this one exactly opposite.

My XR600 has the mixture screw on the engine side. When you turn it clockwise it gets leaner and vice versa. My CR500 has the screw on the airbox side. When you turn clockwise the screw it gets richer.

Of course , this affects mainly the idle engine speed and the transition to the lower revs. I don't remember clearly about CV carbs (I only had the old Ninja) but I think it is the same.

[RXX]

So, if I buy a stock replacement for $34.00 from the dealership, and only replace it evry 15K miles or so, I am OK?

[EVLXX]

It's Plausible.

[HandyAndy888]

Hello everyone,

As far as I know:

1. Air filters should be used.

2. Air filters that are less restrictive are better.

3. Oil coated fabric filters (like K&N and Uniflow) create increased turbulence (over standard paper filters) which mixes better with the fuel and hence explodes better.

My two bit...

[Northman]

which mixes better with the fuel and hence explodes better.

It's a controlled burn, not an explosion.

[shovelstrokeed]

which mixes better with the fuel and hence explodes better.

It's a controlled burn, not an explosion.

Plus the fuel is not mixed in the air box whose prime purpose is to provide a still air enviornment for the intake bell mouths to work in. Turbulance in the combustion chamber - good, turbulance in the air box=bad.

Technology 101.