Cleaning the air filters 1985 fj1100

[Bezmozek]

IMHO here are more aspects mixed together. 

If you have K&N filters, you need just phillips head screwdriver long enough to reach clamps on inner ones and remove.
You have to remove tank, at least it makes thinks way easier, but as ´85 has vacuum operated petcock, there should be minimal if any fuel leakage.
If your petcock does not close, this can be one of the reasons you run rich.

K&N filters are made from wire mesh and cotton vs. Uni pods (or those twins aka bi pods ) are made of foam.
For maintenance of both, you have to clean them and spray with light oil provided with filters.

Huge difference is what will happen later.
If you do not maintain UNI, as it is made from foam, more and more dust will clog pores in foam and filter is more and more restrictive for air and bike runs too rich, but no mess can pass to carbs.
If you do not take care of K&N and similar cotton filters, (they are even less restrictive, you can see through) being more and more restrictive for air will reach a point, that vacuum in your carbs will be strong enough to suck dust into your carbs as it will be stronger than adhesive force of oil.

OK, restrictive.... hmm, if you run constant speed, does not matter on filter, according to engine displacement and RPM, you need certain amount of air/fuel mixture.
Less restrictive filter is, lower vacuum is at the carb filter side. But less vacuum means less fuel sucked into mixture, that is why open filters runs lean.
If you quickly open throttle, vacuum lowers so acceleration pumps were added to enrich mixture.
Filter does not affect speed of air as those are constant velocity carbs, just changes vacuum rate.

How can cone filters increase HP works easy.
Part of the engine power is utilized to make fresh AF mixture flow into cylinders.
Lower vacuum is on intake, lower power needed to waste on this.
Higher RPM means more air that needs to pass filter, more difference can be noticed. (approx 0,000001 HP at WOT)
This is why turbos/chargers are used to help engine breath, polishing intake mainfolds etc.

Another thing is that OEM filter box reduces air spin, so coming to carb, air has constant speed and can be mixed with fuel properly.
Those cone filters make turbulences and AF ratio is not homogeneous.
That can be fixed with velocity stacks, their length matters, but in most of motorbikes, there is not enough space for that.

And last, before you do anything else, just see colour of spark plugs, that shows a lot 

[Pat Conlon]

The air velocity passing thru your CV carbs will increase DECREASE with Uni's, meaning that your needle will be in a slightly lower position in the needle jet, so it is recommended to shim your needles. http://www.fjowners.com/index.php?topic=4714.0

Pat, fixed it for you.  Easy to get confused on this subject

Yeppers, thanks David!  You've been teaching us about this for years now.....one of these days I'll get it right

[red]

Hey Red, I do know about the choke, and it operates as it supposed to . I only use it to start and warm up, and then completely shut it off when riding.  . . .  ill try the seafoam as well, and see if that helps the rich idle.

Ryan,

Great!  See if the simple stuff does any good, first. If only the idle is too rich, that may be a fairly simple (cheap) screwdriver adjustment.  The carb floats may also be set wrong, so I'd recommend using a good MC shop, for the right fix.   Not every MC shop has an Exhaust Gas Analyzer, but that would be the first-class ticket for any carb work.

[ryanschoebel]

You have to remove tank, at least it makes thinks way easier, but as ´85 has vacuum operated petcock, there should be minimal if any fuel leakage.
If your petcock does not close, this can be one of the reasons you run rich.

Hey Bezmozek, you are right, it is a vaccum open petcock. I, however, didnt know that at the time, and turned the fuel cutoff switch to what i believed was off. Turned out, i turned it to prime, and so it just let the fuel pour out in a stream my bad haha.

[FJ_Hooligan]

OK, restrictive.... hmm, if you run constant speed, does not matter on filter, according to engine displacement and RPM, you need certain amount of air/fuel mixture.
Less restrictive filter is, lower vacuum is at the carb filter side. But less vacuum means less fuel sucked into mixture, that is why open filters runs lean.
If you quickly open throttle, vacuum lowers so acceleration pumps were added to enrich mixture.
Filter does not affect speed of air as those are constant velocity carbs, just changes vacuum rate.

How can cone filters increase HP works easy.
Part of the engine power is utilized to make fresh AF mixture flow into cylinders.
Lower vacuum is on intake, lower power needed to waste on this.

A lot of what you're saying is mostly correct but it's a little more complicated.  I do agree that the K&N filter is a bad filter design.

A less restrictive filter flows air slower through the carb compared to the stock filter and airbox.  A CV carb uses the velocity of the airflow to create the vacuum signal that pulls fuel through the jets.  Air flowing at a lower velocity has a smaller vacuum signal.  However, a CV carb responds to this lower vacuum signal by dropping the vacuum slide which reduces the carb throat area.  The smaller venturi area speeds the air velocity back up to the desired (Constant) value which reestablishes the correct vacuum through the carb. 

So, the proper vacuum signal is restored BUT, the vacuum slide is now at a lower level (compared to its position with a stock filter) which means the slide needle is now at a lower (LEANER) position in the needle jet.  That's why the mixture is leaner.

If you open the throttle quickly on a CV carb, the intake vacuum measured at the sync port will drop, but the air velocity through the carb actually spikes momentarily which provides a fuel delivery spike until the vacuum slide reacts to raise the slide and slow the air back down.  Motorcycles (stock) do not have accelerator pumps.

A less restrictive air filter design does affect the speed of the air, with a CV carb the slide needle needs to be shimmed higher to flow more fuel and compensate for the lower vacuum of the slower air.

Class dismissed.

[ryanschoebel]

A less restrictive filter flows air slower through the carb compared to the stock filter and airbox.  A CV carb uses the velocity of the airflow to create the vacuum signal that pulls fuel through the jets.  Air flowing at a lower velocity has a smaller vacuum signal.  However, a CV carb responds to this lower vacuum signal by dropping the vacuum slide which reduces the carb throat area.  The smaller venturi area speeds the air velocity back up to the desired (Constant) value which reestablishes the correct vacuum through the carb.  

So, the proper vacuum signal is restored BUT, the vacuum slide is now at a lower level (compared to its position with a stock filter) which means the slide needle is now at a lower (LEANER) position in the needle jet.  That's why the mixture is leaner....

...Class dismissed.

No, please, class still in session haha, Im still trying to understand  . So, based on what you are saying, if the filters were changed out from the stock filters, but the carbs never adjusted or rejetted accordingly, that could cause it to run rich? or am i understanding that wrong?

EDIT nope, thats wrong. ignore me

[ryanschoebel]

Many a FJ'er has found those filters laying on the top of the engine case after long rides.
So....They don't filter well when they manage to stay on, and they sure as hell don't filter well laying on the top of your engine case.

Now I don't mean to say that you're right,( ) but I was riding around today, and I went over a fairly solid bump. I heard a knock, and lo and behold, look what I found....

[Bezmozek]

A lot of what you're saying is mostly correct but it's a little more complicated. ...

Yes it is, I think we are saying same, but in different ways.

But it is not possible to have slower or faster flow depending on filter.
Still you have to feed 4 cylinders of your engine with A/F mixture, so if you have OEM filter, with same carb settings, butterfly valve position etc, does not matter on speed of air, you need 1097 cm3 of mixture to feed FJ 1100.
If you change to Uni/K&N as you say air will flow slower, but than you do not have enough A/F mixture to run your engine.
As Bernoulli says, faster the air goes through carb, lower pressure it has.
But bike carb does not use air speed to operate. It is all about pressure, via diaphragm raise/lover needle according to differences between pressures.
But with moving just needle, in different RPM will change the speed of air, so that is why throttle slide is changing throat diameter to keep constant velocity.

While changing to hi-flow filter, you are changing vacuum level at the intake, which means one side of equation  

[FJ_Hooligan]

Yes it is, I think we are saying same, but in different ways.

But it is not possible to have slower or faster flow depending on filter.
Still you have to feed 4 cylinders of your engine with A/F mixture, so if you have OEM filter, with same carb settings, butterfly valve position etc, does not matter on speed of air, you need 1097 cm3 of mixture to feed FJ 1100.
If you change to Uni/K&N as you say air will flow slower, but than you do not have enough A/F mixture to run your engine.
As Bernoulli says, faster the air goes through carb, lower pressure it has.
But bike carb does not use air speed to operate. It is all about pressure, via diaphragm raise/lover needle according to differences between pressures.
But with moving just needle, in different RPM will change the speed of air, so that is why throttle slide is changing throat diameter to keep constant velocity.

While changing to hi-flow filter, you are changing vacuum level at the intake, which means one side of equation  

No, we are not saying the same thing.

With a CV carb, it's not the AMOUNT of air it's the VELOCITY of the air. Yes, the intake stroke is filling the volume of the cylinders with an air/fuel mixture but it's sensitive to the rate of airflow and not simply the amount of air.

Bernoulli says the FASTER the air flows through the carb the HIGHER the vacuum.

A CV carb is all about the speed of the air and NOT the quantity.  Yes, the position of the slide is dependent on the vacuum, but that vacuum is created by the airflow velocity

If you don't understand that then you don't understand CV carbs

[FJ_Hooligan]

Read the link that Pat provided.

[FJ_Hooligan]

I can see that we're having a language translation problem.  Sorry about that.

You say Bernoulli says the faster the air goes through the carb, the lower pressure is has.

We are agreed!