K & N Filter Yes or No ?

wjbertrand

Ventura Highway
Joined
Feb 8, 2005
Messages
4,407
Location
Ventura, CA
hi ,

K& N air filter - definite yes for me... why ?

- cost effective over the period of the miles completed on the bike. ( If you have the cleaning & oil kit.)
- better throttle response / reaction. ( improvement yo can feel !)
- Million mile filter guarantee

I have fitted these to all my vehicles over the past 20 years and never had an issue to date. ( 12 cars , 20 different motorbikes.)

the dirt and sand in the Airbox is most probably the location you are in the world.... or what terrain you ride in.

I service my filter every 15 to 20 K miles

I have always used them , and always will.

regards

Tony
I don't think of the UK as a very dusty place so your experience is understandably different to many of us living in dry, arid regions in the southwestern US. One thing you cannot top K&N on is their marketing department!
 
Joined
Sep 22, 2015
Messages
1,282
Location
Wasaga Beach, Ont. Canada
Bike
'04 ST1300 Blue STar
K&N,,, yes or no,,,, I you just kind of like your engine,, it's yes,,, if you love your engine,,, it's NO. I live in a sandy Beach town,, so the previous owners K&N sits on the shelf,, while I alternate an OEM filter with a HiFlow filter. They can be cleaned and reused,,, you know,,, Cat'
 

Blrfl

Natural Rider Enhancement
Joined
Aug 24, 2005
Messages
5,689
Age
55
Location
Northern Virginia
Bike
Fast Blue One
STOC #
4837
For the folks who are unlucky enough to live in California, keep one thing in mind, our bikes come from the factory very lean to begin with, and dropping in a K&N filter, will make them run even leaner!
Open-loop FI has to be remapped, but a closed-loop system will adjust unless the filter flows so much more air that the firmware isn't willing to correct for it.

--Mark
 

ST Gui

240Robert
Site Supporter
Joined
Sep 12, 2011
Messages
9,262
Location
SF-Oakland CA
Bike
ST1300, 2010
Blrfl said:
Open-loop FI has to be remapped, but a closed-loop system will adjust unless the filter flows so much more air that the firmware isn't willing to correct for it.
I don't know the difference between the two systems (or even that there were two) so in my ignorance I assume that FI would compensate to the degree possible.

My 750-K4 had first a K&N then later four of them. Looked very cool and sounded totally bada**. LOVED that. But I had to adjust the carbureted mixture both times. Not an insignificant undertaking for me.

In contrast when I tried K&Ns on my 750 Duc (it shipped with velocity stacks and stone guards!) they couldn't flow nearly enough air and it felt like I was running on half a cylinder. Two giant green foam filters worked out just right— no more fiddling required.
 

Blrfl

Natural Rider Enhancement
Joined
Aug 24, 2005
Messages
5,689
Age
55
Location
Northern Virginia
Bike
Fast Blue One
STOC #
4837
I don't know the difference between the two systems (or even that there were two) so in my ignorance I assume that FI would compensate to the degree possible.
Closed- and open-loop are terms used in control theory to describe whether or not a system uses feedback to govern its operation.

Open-loop systems make decisions based on before-the-fact input or assumptions but have no idea whether or not they're doing the right thing. An open-loop FI system may incorporate data from sensors in the intake (e.g., temperature and manifold pressure) into its fueling decisions, but it might make the assumption that the flow rate through the air box is some fixed value. This means that at the same temperature and pressure, the amount of fuel it squirts in will be the same. If you put on a freer-flowing air filter and don't reprogram the system to add more fuel, the old assumptions are going to make it run lean. As the filter clogs up, the system will run richer. What you experienced with the carburetors on your K4 and Duc is open-loop behavior at its most basic, and you had to change either the assumptions (jets) or environment (air filter) to make them run well. Carburetors are stymied by having one or two configurations that have to get it in the ballpark of right under a wide variety of conditions and are, by today's standards, a very ham-fisted way to fuel an engine. (And that's when the fight started... :cool:)

Closed-loop FI uses sensors placed after the combustion process to get an idea whether or not it's making the right decisions. It turns out that the amount of oxygen in the exhaust stream is an indicator of whether the mixture is lean, rich or just right. The oxygen sensors feed that information back to the ECM in real time, and the ECM continuously increases or reduces the amount of fuel in the mixture to get the ideal result. Some systems are even smart enough to use the measurements to figure out the right fueling for each individual cylinder even if they only have one or two sensors. Closed-loop FI is the single biggest reason modern engines are as good as they are: we're loads better at fueling them than we were with open-loop (carb'd or FI).

One thing to note about closed-loop FI systems is that they're actually dual-mode, meaning that they operate open-loop when they don't have enough information to make the best decisions. Oxygen sensors don't work until they're very hot, so the system operates on best-guess assumptions from the time you thumb the starter until the time they start producing meaningful data. This is also why the 1300 won't leave you stranded at the side of the road unless it can't determine the position of the engine or it can't see one of the fuel injectors. For all of the other sensors, it can operate on assumptions based on average conditions. The engine won't run ideally, but it'll still run well.

--Mark
 

wjbertrand

Ventura Highway
Joined
Feb 8, 2005
Messages
4,407
Location
Ventura, CA
Mark is correct, our ST13s have both open and closed loop modes as do most EFI systems these days. Whether the engine is running in open or closed loop mode depends on operational conditions. Open loop running typically happens when the engine is cold or not yet fully warmed up, at high RPM (more than about 50% of redline) or at large throttle openings. Closed loop running only occurs at light throttle openings, when the engine is fully warmed up, and when RPMs are at about 50% or less of redline. When running in closed loop the ECM uses information from the O2 and other sensors to adjust the mixture continuously while at open loop it is running off of a fixed pre-programmed code in the ECM.
 

T_C

Joined
Mar 8, 2012
Messages
4,341
Location
St. Louis, MO
Bike
2005 St1300
STOC #
8568
Open loop running typically happens when the engine is cold or not yet fully warmed up, at high RPM (more than about 50% of redline) or at large throttle openings. Closed loop running only occurs at light throttle openings, when the engine is fully warmed up, and when RPMs are at about 50% or less of redline.
Curiosity, why the switch on the RPM at 50%? I know it happens on my bike with the pulse divider. If I spend 15 seconds at 5200 rpm it lights the FI light until I re-start. But pre pulse divider I bever noticed this. Some code in the ECM??
 

wjbertrand

Ventura Highway
Joined
Feb 8, 2005
Messages
4,407
Location
Ventura, CA
Curiosity, why the switch on the RPM at 50%? I know it happens on my bike with the pulse divider. If I spend 15 seconds at 5200 rpm it lights the FI light until I re-start. But pre pulse divider I bever noticed this. Some code in the ECM??
Don't know the reason things are set up exactly like that, but it appears to be pretty common practice across different manufacturers for both cars and bikes.
 

Blrfl

Natural Rider Enhancement
Joined
Aug 24, 2005
Messages
5,689
Age
55
Location
Northern Virginia
Bike
Fast Blue One
STOC #
4837
If I spend 15 seconds at 5200 rpm it lights the FI light until I re-start. But pre pulse divider I bever noticed this. Some code in the ECM??
Have you asked it what's wrong? That sounds like a failed knock sensor, but the magic number for that is > 4,000 rpm.

--Mark
 

T_C

Joined
Mar 8, 2012
Messages
4,341
Location
St. Louis, MO
Bike
2005 St1300
STOC #
8568
Have you asked it what's wrong? That sounds like a failed knock sensor, but the magic number for that is > 4,000 rpm.

--Mark
No codes given, checked while the light was still on and on immediate re-start. Others have experienced the same thing. It only happens with the Rostra branded pulse divider.
 

technotony007

Marvellous !
Joined
Oct 30, 2016
Messages
146
Location
durham ,uk
Bike
2005 Pan Euro ST1300
Closed- and open-loop are terms used in control theory to describe whether or not a system uses feedback to govern its operation.

Open-loop systems make decisions based on before-the-fact input or assumptions but have no idea whether or not they're doing the right thing. An open-loop FI system may incorporate data from sensors in the intake (e.g., temperature and manifold pressure) into its fueling decisions, but it might make the assumption that the flow rate through the air box is some fixed value. This means that at the same temperature and pressure, the amount of fuel it squirts in will be the same. If you put on a freer-flowing air filter and don't reprogram the system to add more fuel, the old assumptions are going to make it run lean. As the filter clogs up, the system will run richer. What you experienced with the carburetors on your K4 and Duc is open-loop behavior at its most basic, and you had to change either the assumptions (jets) or environment (air filter) to make them run well. Carburetors are stymied by having one or two configurations that have to get it in the ballpark of right under a wide variety of conditions and are, by today's standards, a very ham-fisted way to fuel an engine. (And that's when the fight started... :cool:)

Closed-loop FI uses sensors placed after the combustion process to get an idea whether or not it's making the right decisions. It turns out that the amount of oxygen in the exhaust stream is an indicator of whether the mixture is lean, rich or just right. The oxygen sensors feed that information back to the ECM in real time, and the ECM continuously increases or reduces the amount of fuel in the mixture to get the ideal result. Some systems are even smart enough to use the measurements to figure out the right fueling for each individual cylinder even if they only have one or two sensors. Closed-loop FI is the single biggest reason modern engines are as good as they are: we're loads better at fueling them than we were with open-loop (carb'd or FI).

One thing to note about closed-loop FI systems is that they're actually dual-mode, meaning that they operate open-loop when they don't have enough information to make the best decisions. Oxygen sensors don't work until they're very hot, so the system operates on best-guess assumptions from the time you thumb the starter until the time they start producing meaningful data. This is also why the 1300 won't leave you stranded at the side of the road unless it can't determine the position of the engine or it can't see one of the fuel injectors. For all of the other sensors, it can operate on assumptions based on average conditions. The engine won't run ideally, but it'll still run well.

--Mark
Thanks for that , good explanation :yr1:
 
Top Bottom