Articles & photos


Developing XR1200-XR1200X HPA airbox

13-6-2019 - In this article we will show you the development of a XR1200 High Performance airbox HPA from Twin Motorcycles.

Update 15-11-2011:

After I spend hours and hours in the dyno with Tube Buell's that have a complete different airbox design and with Buell XB, and tested different engine setup's I was sure that there was a improvement in the stock airbox design from the XR1200 and XR1200X. After developing the Torque Hammer exhaust for the XR1200, I decided it was time to finisch this project. I work together in this project with a external Prototyping company. The reason for this is pure time. I need to develop a new intake stack in different lenght for testing, in the dyno to find the best lenght for the Torque Hammer exhaust and I need to develop a new intake manifold rubber, a bottom with a thick layer of heat isolating material, and a new carbon fiber airbox with a much bigger filter area.

Below i show you the start of this airbox and later the testing in the dyno.

After i had some ideas and thoughts i talked it through with the prototype company and we started scetching:



We needed to make a much bigger filter area, design a new intake manifold and make it variable for testing in the dyno. The filter surface is 145% bigger then the original filter surface. We we also make louvres at the right side to force cold air in the airbox.


In the picture below, you see the bottom of the airbox, with the new designed rubber for the intake manifold, In this picture you can also see the brown foam where we will be adding on the complete bottom heat treatmant material in the carbon fiber. This is to prevent the air in the airbox to heat up to much as happends in the stock plastic airbox. Cooler air is always better for performance then Hot air. The heat wall will be around 5mm thick.

In the pictures below, you can see how the intake stacks will look like. We need to find the ideal lenght for this setup. We will test with 2 different exhaust systems. The Torque Hammer 2-1 and the Termignoni 2-1 system. This will give us good test information for making choices for the Torque and HP area on the different setups.


Top side airbox, This is hold stock for the perfect fitting under the OEM Fuel tank. The topside is trenghtened but kept as original as possible. BE aware this is a prototype for fitting.


In the picture below, You can see the concept of the airbox schematicly, how it is going to look. The picture below is the top view, Here you can see the place of the components. De airbox is TWICE as big as the stock airbox in volume, that means MORE airfilter AREA.

In the picture below, You can see the louvre design that will help the cold air to be forced into the airbox.

We are now working on the last modifications before we can test the prototype.

 - Resize the airfilter for this airbox, and find a stock one from K&N

- Desiging the side wall under the tank

- Fitting the Intake stack

- making the Louvres at the side for forced air.

Wish it was ready already to test it on the dyno.


Update 2-12-2011:

Picked up the XR1200 Today with the prototype airbox, below are some pictures to give you a idea what we developed. KEEP IN MIND THIS IS A PROTOTYPE FOR TESTING ONLY (-:

First the different stack's

The biggest intake just for gatherring flow data and data for analyzing no restriction puur open system no filter

Then the short stack to see the results with the bigger airbox and filter

Then the 2 pieces i can use to shorten back after every run the long stack made from 2 pieces:

and fitted together

Some little flow gadgets to test inside the airbox

 And something to test just for my experience with a rubber inlay, for the exhaust pulses just for personal experience, the inside ring is made from flexable rubber.

The filter 140% more surface

And the airbox, below made of 2 pieces this is the side vieuw pointed forward as mounted on the bike.


Front View


Bottom view, just some heat material this is NOT the final version. You can also see the new rubber ring, that CANNOT leak the same way as the stock rubber ring.


 And a look inside you can see the metal frame we made for the filter.


And a view from the side inside

 And a top view

Next week i start testing and try to show you all what the results are with the different stack lenghts and intake sizes.

Update 7-12-2011:

After a long day in the Dyno, and with help from Jeroen, he is a student for a technical Education and has no Motorcycles experience (not even his drivers license for a Motorcycle) we did a lot. 2 extra hands are always welcome.

We tested a lot of stuff I will write tomorrow the story but to let you all now what we did today.

Below is the graph after a lot of product testing. The Motorcycle we used is my own stock 2010 XR1200, It has a new set of new pistons and cylinders and is very low mileage. The previous pistons had very bad piston rings. When this engine has more mileage, it will make a little more power. With off course a Torque Hammer exhaust and the TTS software, In the morning i filled the gas tank with 95 octane fuel. All dyno data is done in the same dyno room at the same day, at the same engine temperature with me Dris as a dyno operator under the same conditions.

We started with the stock airbox and a K&N filter, and ended up with the new airbox mounted with the stack lenght that untill now worked the best. We gaind 6 HP and 5 NM of Torque. Below is the sheet we have a lot more runs and I will post more results tomorrow. KEEP IN MIND WE DON'T CHANGE FUEL WHEN TESTING ALL TEST ARE DONE UNDER THE SAME ECM SETTING'S. WE WILL DO THAT LATER. WE ARE ONLY GATHERING DATA HERE. ALL TEST HERE ARE DONE WITH DB-KILLER IN THE EXHAUST.



Tomorrow more data..


Update 8-12-2011:

Here are some picture of the XR1200 in the Dyno. I hooked her up with 2 wideband sensors and use the same fuel in all test so No tuning in the results.

Here is the damage from yesterday, we cut different lenght stacks. I stop here and today richard is bringing his bike with the stock airbox and 2-1 Termi exhaust.

Update 9-12-2011:

Here are the test results from our own XR1200 2010. Low Mileage becuase of the new Cylinders and pistons.

 In the sheet below, you can see the results with the big Carbon elbow. The problem with testing this is that we only had 1 lenght. So we can't say if this is a good or bad result, Shorten the lenght, or making it longer will give totally different results. We can tell that compared to the stock airbox it is a good result, but you can't ride this on the street becuase of all the birds, and animals that get sucked in.

And the dyno sheet:


In the sheet below we compare the stock airbox with k&n filter compared to the new airbox with the longest stack we had. Besides the bike is pinging like hell (it doesnt likt it) at midrange we see a good result at low RPM and we see it kills top end Horse power, But it makes the 5000 RPM area much stronger. The problem we have now that we cut this piece to test more later in the article. I hope we have a new version next week for more testing.


IN the sheet below you see 2 runs, with a different intake lenght of 1 CM, (0,39 inch) This is the 90 degree bent. You can see that the shorter version Blue Line is gathering more top end HP, It also add's a little at low RPM but we loose at midrange.


We will do all this testing again with NO db-Killer installed also. That will make a nice flat torque curve. and will give a different result.



I will now show the test results of Richards bike with the 2-1 termi installed.



Here is a run with the stock airbox. We closed a modification with Tape, that was made in the front of the airbox.


Here you can see the stock run with the big Carbon elbow installed compared to stock. It make a good top end power.


Here is a run with the stock airbox and with a little hole made at the right side of the airbox, that is cheap HP and Torque.



Below is the stock run on Richard's Xr1200 compard with the new airbox (RED LINE) with the short stack. The problem is that we test new setup's next week, becuase then we have all the stack. Also not bad compared to the stock airbox It gained HP and Torque all over the RPM range.



MORE TEST RESULT WITH 2010 XR1200 Torque Hammer with NO DB-KILLER

Oke, Now the test result of the Torque Hammer with no-db-killer and the Termignoni with no db-killer with the same airbox setup's. All data is SAE Correcte dmeasured on the REAR WHEEL.

Here is a compare between the Torque Hammer 2-1 and the Termignoni 2-1 both run the big carbon intake. The blue line is the 2-1 termi, the red version is the Torque Hammer both run NO db-killer.


Here is a compare With the new airbox we are developing. We installed on both bikes the new airbox with the short stack. Look down for the results.

The Blue line is the Termignoni 2-1 and the red line is the Torque Hammer 2-1.


And here is my dynosheet of the Torque Hammer with the new Airbox sofar.

94,6 HP and 108 NM of Torque. Now we are talking baby. I will add some more dyno data later.


Update 14-12-2011:

This part is for my friend Scotty on the XR1200 Ownersgroup website (-:

Today we tested the stock airbox agian, bacause my helpful vriend scotty asked me to do so.

We filled the bike with 95 octane Shell Fuel. We checked the tyre pressure and set it to 2.6 bar, all runs where done at 150 degrees head temp.

We first run the Bike without the dd killer in the Torque Hammer

Whe then taped the famous hole in the airbox with black ducktape and made the run

Whe then too the tape off and made another run, in the graph below you can see the results



The run made with the stock airbox and the hole taped, and Torque Hammer with NO db-killer and  was:

88,6 PP and 107 NM Torque

The run made with the stock airbox and the hole open and Torque Hammer with NO db-killer and was:

90,4 PP and 108 NM Torque

So we gained 1,8 HP and 1 NM of Torque



The run made with the stock airbox and the hole taped, and Torque Hammer with WITH db-killer and was:

89,2 PP and 103 NM Torque

The run made with the stock airbox and the hole open and Torque Hammer with NO db-killer and was:

91,3 PP and 105 NM Torque

So we gained 2.1 HP and 3 NM of Torque


As we are ready with the stock airbox testing, here are some pics of the new intakes we are going to test. It's gone be a long day:

After we decided what the lenghts where and what the diamters where, we numberd all the pieces and started. We have 5 different pieces to test on different lenghts today look down for the parts:

Top vieuw:


Side view

Upate 15-12-2011:

Oke we are done with all the stack testing and found our right size stack. When we tested the XR1200 with the stock airbox and K&N filter the results where 88,6 HP and 107 NM of Torque. This was done on a 2010 XR1200 with a Torque Hammer exhaust and a good tune not on a stock bike. After we developed the new airbox and finding the right stack size and lenght and diameter we ended up with 94,2 HP and 108 NM of Torque. We gained 5,6 HP with the new airbox. Look at the graph down.


To give you an idea, what the performance is of a stock XR1200 or XR1200X straight from the factory, and when mounted our Torque Hammer exhaust, Tune and airbox, look down.



It pulls, like a freaking train.We are now going to take the airbox in production and start with making the final version.

We wil design 2 types and see which one it is going to be. It will take about 6 weeks to be ready for ordering.


Update 16-12-2011:

Oke first of all with the new airbox, the complete caracteristic of my slipon (that i developed on the old style airbox) was gone. It lost torque in the mid-range RPM area and i didn't like that at 4000-5000 RPM. The complete power band and Torque band is better then it ever was with the new airbox but i didn;t like it. Below is a sheet with and withhout db-killer.


Today I tested also my new slip-on without thye db-killer to get a good compare with my current Torque Hammer for the XR1200. Here are some pictures of the prototype slip-on. The headers are the same, we only changed the inner parts.


Oke and now the dyno graph. I lost top end HP 1-2 at 6500 RPM, but holey shit look at that Torque.... massive all the way no dips, no fall back straight like a arrow. The red Graph is from the new Airbox with the new airbox and the blue graph is from the New Airbox with the old style slip-on.




Here is a graph with only the run with the new slip-on Torque Hammer.




Here are some pictures of the prototype:



Now I am going to develop the right db-killer for it and where done..

Here is a graph to show the difference with the new airbox between the termignoni 2-1 systyem and our Torque Hammer 2-s system.

The red lines is the Torque Hammer with the new slip-on and the Blue line is the termi 2-1. I will do more testing nextr week with the Termi.


Update 29-11-2011:


Mounted the Torque Hammer that came from my test XR1200 on Richard XR1200 for some more testing look at the picture below.


Here is a graph with the Torque Hammer and the new airbox from today beautiful results.


Here is the result from today when i mounted the Stock airbox with the famous hole compard to the new airbox. 


And here is the graph with the tuned 2-1 Termignoni and the Torque Hammer both with the new airbox. There is a big big torque difference.



This difference is so big that you will loose at a stoplight sprint.. Later more news when the 2 new designs are there from the airbox. 

Oke and here is a compare with the 2 bikes and the identical setup (Torque Hammer and New Airbox) The difference is that the blue graphs are a tuned setup and the red graph is a setup from richards bike tuned for a different exhaust.



Update 8-2-2012:


Here are some pictures of the new airbox, keep in mind this is only the moulding model. NOT the final model.

We will use a small steel breather material like the original airbox in the front on 2 sides.


update 10-1-2012:

More picture, This is the near final prototype that will be used to make the moulds for series production. Completely handmade from hard modeling foam. This takes an almost scary amount of skill, precision and time. 

The light grey areas mark the intakes that will get a fine stainless mesh to keep insects & debris from the K&N high flow filter inside. The total intake area is nearly 3 X larger than stock!

The airbox has a larger volume but retains the stock design and shape. Despite the larger volume, we managed to make the airbox follow the lines of the fuel tank better than stock with some slight modifications to the outer profile. The Torque Hammer ® High Performance Airbox looks even sleeker and more integrated than the stock airbox for the XR1200.







update 11-1-2012


To Give you all an idea how much time it cost to develop some little very essential parts, here are some pictures of the development of the intake stack.





Update 11-2-2012:

Here are some pictures to give you an idea about the difference with the stock filter and airbox and our new filter we use.



Update 13-3-2012

We are working very hard to get the moulds ready for production, Here you can see the first prototype coming out the moulding and the moulds we developed.


Update 23-3-2012:

Oke the first examples are now coming off the moulding. The Top of the airbox worked quiet well look down.


The bottom of the airbox is a little bit complicated. Look at the picture below:

We now make a prototype for testing I can pick up up today, We are not happy yet with the way the intake stack fit's the lower part of the airbox and we work on that right now. It all is coming together now. This weekend we will test this setup with our Final prototype of the exhaust.

Update 24-3-2012:

 And here are the pictures of the new prototype with airbox ready for testing with the exhaust.

update 27-3-2012

Today i dynoed Richard's bike with the new race slip-on no db-killer and our New airbox in the final design.


I pulled uncorrected 101.1 HP and 118 NM of Torque. (am i the first who achieved the 100+ HP on a stock engine?



When i use my SAE correction wich is heavy with my barometric correction and Weather correction we achieved 95 HP and 111 NM of Torque



n the sheet below, You can see the last dyno run with our prototype airbox RED LINE and our prototype exhaust and prototype airbox compared to our new stage 1 kit with new exhaist and new airbox . Both have SAE Correction


I think we made the best complete kit in the market that nobodu untill today will beat.

Update 28-3-2012:

I mounted todat the old style TH1 Headers and the new STYLE TH2 slipon with pipe, fit's perfect and directly a nice upgrade product for the Torque Hammer version 1 customers who like to upgrade.


Richard piked up his own bike this morning:


And now it is my time. My XR1200 is back from the Airbox Developer, project is finished we start production next week.

I mounted the Torque Hammer 2-1 system to see when i load the TTS Mastertune map that i make for Richards bike what the HP and Torque Curves are and will make a fuelmap for the setup installed with the db-killer so we have 2 fuelmapos ready for the race muffler. 1 version without db-killer and the High Performance airbox and 1 version with db-killer and the High Performance airbox.



Fitted on another customers bike


Update 26-7-2012

We updated the moulding and the design of our new airbox with some extra bolts to prefent the airbox from having a little opening in the front and rear.

We are also for our first airboxes making a new rubber moulding (that is been done as we speak) that we send for free to all our XR1200-XR1200X customers that ride with a HPA Airbox. HEre are some pictures of the new design: