Sportster air cleaner theory

12965 Views 12 Replies 7 Participants Last post by XL1200R, Aug 30, 2014

XL1200R

Discussion Starter · Aug 27, 2014

Hey guys,

I've gotten to thinking about the following:

1. The 1200 and 883 Sportsters for the years 2004-2006 (Other years apply as well I am sure, I am just 100% confident of these years so I will stick to them for the rest of the rambling) use the same air cleaner. It is the same part number for the backing plate, the filter element....etc

2. Obviously the 1200 requires much more air than the 883 because it is a larger engine...makes sense right?

3. So, in theory being that the air cleaners are the same the air cleaner on the 883 is WAY overkill for a stock 883 right? That means that a stage 1, (maybe even 2) 883 should be able to pull plenty of air through the stock cleaner no?

I don't know if anyone has tried it but I feel like an 883 with a tuner and pipes should perform the same as one with tuner, pipes, and an upgraded air cleaner because in theory the air cleaner is not the limiting factor.

Am I way off base on this theory?

The only thing that it doesn't account for is the turbulence of the air and temperature of the air so maybe an upgraded air cleaner changes that stuff enough to gain more power?\

Save

1 - 13 of 13 Posts

Brodie5775

· #2 · Aug 27, 2014

I don't think there is "overkill" on airflow with basic ACs (as long as you compensate the fuel mixture) that's like saying a supercharger would "overkill" every car engine. I think the airflow helps any engine. I have an 883 and with stock pipes and no tuner I could feel the difference with a better AC. Then with pipes and a tuner it's like night and day. I think basically the stock AC is crappy on both 1200 and 883s. Not to mention it's disposable and where I live there's lots of dust so that's means replace every 3-4 months.

Sent from Motorcycle.com Free App

Save

damager

· #3 · Aug 27, 2014

While on the subject of air cleaners / filters (particular concerning bikes with a Stage 1 / 4)... I noticed that NOWHERE in the Harley Service manual does it ever say anything about REPLACING the air filter. Even at the scheduled service times (1K, 5K, 10K, so on...). In fact... here's what it says VERBATIM..... "Inspect, service as required." Well $h1t... i can take a gentle brush and brush all the $h!t off easily. I can't believe I'm asking this cuz it sounds ludicrous, but does the filter ever NEED a replacement, short of a rodent getting in there and chewing it to pieces?

Save

83XLX

· #4 · Aug 27, 2014

The stock air cleaners have a restrictive element and a small opening for air to get into the box, mainly for noise control. A backing plate that allows more air in and a less-restrictive filter element will make a significant difference in either size engine, as long as the mixture is adjusted accordingly.

Save

Dave63

· #5 · Aug 27, 2014

XL1200R said:
Hey guys,

I've gotten to thinking about the following:

1. The 1200 and 883 Sportsters for the years 2004-2006 (Other years apply as well I am sure, I am just 100% confident of these years so I will stick to them for the rest of the rambling) use the same air cleaner. It is the same part number for the backing plate, the filter element....etc

2. Obviously the 1200 requires much more air than the 883 because it is a larger engine...makes sense right?

3. So, in theory being that the air cleaners are the same the air cleaner on the 883 is WAY overkill for a stock 883 right? That means that a stage 1, (maybe even 2) 883 should be able to pull plenty of air through the stock cleaner no?

I don't know if anyone has tried it but I feel like an 883 with a tuner and pipes should perform the same as one with tuner, pipes, and an upgraded air cleaner because in theory the air cleaner is not the limiting factor.

Am I way off base on this theory?

The only thing that it doesn't account for is the turbulence of the air and temperature of the air so maybe an upgraded air cleaner changes that stuff enough to gain more power?\

An 883 or 1200 air cleaner can flow more air than that engine can digest, so it's not an issue.

Yes an 883 is smaller than a 1200, but the air cleaher isn't the deal breaker.

I'll explain a simplified version of air filters and what the benefits are to some, but how OTHER THAN APPEARANCE, most aftermarket filters are a waste of money, unless you're going to add more fuel to make them a complete modification.

They do help with certain applications where max cfm levels are needed over a stock filter on WOT pulls, but only on larger engines or smaller engines with cams. But you wouldn't keep a stock filter on an engine like that anyway.

Your engine: 74 CI x 5300 / 3456 = 113.48 cfm

Stock filter flows 130 cfm max.

Open the back of the backing plate to get in more air to the filter.

Engines need air. To determine how much air you need (cfm's) you do the math: (simplified)

Cubic inches x max rmp / 3456.
(Using a 1.5" restriction on the flow bench)

So....some examples of cfm requirements:

*88 ci x 5200 rpm ÷ 3456 = 132.4 cfm.

*96 ci x 5300 rpm ÷ 3456 = 147.2 cfm

*103 ci x 5300 rpm ÷ 3456 = 157.95 cfm

This is why CVO bikes come with different filters.

Stock Harley elements flow 130 cfm

Screamin Eagle stage-I elements are 210 cfm

Flowing more air in is great, but at WOT, unless you add more fuel, you gain nothing. On a dyno run, you'll see a lean trend on higher rpms as the O2 sensors will only adjust so far, so fast as they're narrow band units and not wide band.

So.....for the most part, you'll only gain performance if fuel is added as well. That means XEIDS or a tuner.

Outside of that, you're ECU will maintain 14.7:1 AFR and the "performance" filter brings you as much performance as an STP sticker on the gas tank.

The K&N is washable.....but so it your stock filter element.

See less See more

Save

XL1200R

Discussion Starter · #6 · Aug 27, 2014

Dave63 said:
An 883 or 1200 air cleaner can flow more air than that engine can digest, so it's not an issue.

Yes an 883 is smaller than a 1200, but the air cleaher isn't the deal breaker.

I'll explain a simplified version of air filters and what the benefits are to some, but how OTHER THAN APPEARANCE, most aftermarket filters are a waste of money, unless you're going to add more fuel to make them a complete modification.

They do help with certain applications where max cfm levels are needed over a stock filter on WOT pulls, but only on larger engines or smaller engines with cams. But you wouldn't keep a stock filter on an engine like that anyway.

Your engine: 74 CI x 5300 / 3456 = 113.48 cfm

Stock filter flows 130 cfm max.

Open the back of the backing plate to get in more air to the filter.

Engines need air. To determine how much air you need (cfm's) you do the math: (simplified)

Cubic inches x max rmp / 3456.
(Using a 1.5" restriction on the flow bench)

So....some examples of cfm requirements:

*88 ci x 5200 rpm ÷ 3456 = 132.4 cfm.

*96 ci x 5300 rpm ÷ 3456 = 147.2 cfm

*103 ci x 5300 rpm ÷ 3456 = 157.95 cfm

This is why CVO bikes come with different filters.

Stock Harley elements flow 130 cfm

Screamin Eagle stage-I elements are 210 cfm

Flowing more air in is great, but at WOT, unless you add more fuel, you gain nothing. On a dyno run, you'll see a lean trend on higher rpms as the O2 sensors will only adjust so far, so fast as they're narrow band units and not wide band.

So.....for the most part, you'll only gain performance if fuel is added as well. That means XEIDS or a tuner.

Outside of that, you're ECU will maintain 14.7:1 AFR and the "performance" filter brings you as much performance as an STP sticker on the gas tank.

The K&N is washable.....but so it your stock filter element.

Thanks Dave...this is essentially what I was thinking in my head I just didn't really know how to figure it out mathematically like you have done.

Save

Brodie5775

· #7 · Aug 27, 2014

damager said:
While on the subject of air cleaners / filters (particular concerning bikes with a Stage 1 / 4)... I noticed that NOWHERE in the Harley Service manual does it ever say anything about REPLACING the air filter. Even at the scheduled service times (1K, 5K, 10K, so on...). In fact... here's what it says VERBATIM..... "Inspect, service as required." Well $h1t... i can take a gentle brush and brush all the $h!t off easily. I can't believe I'm asking this cuz it sounds ludicrous, but does the filter ever NEED a replacement, short of a rodent getting in there and chewing it to pieces?

When I changed mine the dirt was imbedded into the element so it want able to brush it off, I tried while I was waiting for my new AC in the mail. I was having an issue of overheating in traffic as well with the old AC. Living in the desert is definitely too hard on the stock.

Sent from Motorcycle.com Free App

Save

bobf

· #8 · Aug 29, 2014

What it all boils down to is, "normal" street use of a 883 or 1200 isn't gonna see much if any difference by changing the AC, even if you goose up the fuel, the main difference will only be seen at WOT. For most riders= waste of money.

Save

Dave63

· #9 · Aug 29, 2014

I have the STP sticker on my gas tank....so I got that going for me.........

Save

XL1200R

Discussion Starter · #10 · Aug 29, 2014

Dave63 said:
I have the STP sticker on my gas tank....so I got that going for me.........

And I have a motorcycle superstore sticker on my toolbox so that makes me a good motorcycle mechanic right?

Save

Dave63

· #11 · Aug 30, 2014

Yep. You get it.

Save

southernman_67

· #12 · Aug 30, 2014

So.... Um.... Where can I get on of these STP stickers , and will it work on say a TC88?

Sent from Motorcycle.com Free App

Save

XL1200R

Discussion Starter · #13 · Aug 30, 2014

southernman_67 said:
So.... Um.... Where can I get on of these STP stickers , and will it work on say a TC88?

Sent from Motorcycle.com Free App

Hell no...

You need an amsoil sticker on twin cam 88s to make them faster.

The sticker let's the engine turn with less drag giving you more power.

You can also add 2 more stickers for the Trans and primary and the bike shifts better too!

Save

1 - 13 of 13 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.

Top Contributors this Month