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Discussion Starter #1
Is the k&n air filter worth having in the voyager since the air box is so restrictive, that only so much air can be sucked in anyway?
 

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I put my KNN in and then took the airbox cover off the other side. I removed the rubber volosity stack. It was really close to the cover. Seemed to help
 

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Is the k&n air filter worth having in the voyager since the air box is so restrictive, that only so much air can be sucked in anyway?
I'm selling mine since I upgraded to a Thunder kit - asking $40 (plus $5 for shipping). Like new (1,037 miles) K&N Air Filter (KA-1709). Includes original packaging & Installation Instructions.
 

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I put my KNN in and then took the airbox cover off the other side. I removed the rubber volosity stack. It was really close to the cover. Seemed to help
Does anyone understand what the velocity stack is there for ? Anyone else removed it?

Opinions please?
 

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I'm selling mine since I upgraded to a Thunder kit - asking $40 (plus $5 for shipping). Like new (1,037 miles) K&N Air Filter (KA-1709). Includes original packaging & Installation Instructions.
Top - I may be interested in this too . . . You ever get up around Quantico?
 

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Does anyone understand what the velocity stack is there for ? Anyone else removed it?

Opinions please?
SORRY, i cannot offer opinions on velocity stacks, but i can offer the facts!!:D

Velocity stacks have many affects on engine performance, and this is accomplished in a few ways.

The total length of the intake system, from the intake valve(s) to the air entranceway determines the rpm where the engine makes peak power. Changing this length will change the shape of the power band, the rpm where peak power is produced and the amount. Shortening the velocity stack length will move the rpm higher where peak power is produced, and may increase peak power. Sometimes there is the "rob from peter to pay paul" consequence. Depending on how short the stack is made, no power may be sacrificed at the lower rpm's. If the stack is too short, then there may be losses in low and midrange power, poorly shaped powerbands will occur. I have seen stacks so short that SEVERE compromises in the powerband occur, with the rpm where peak power occurs just a few rpm from the rev limiter!

Conversely, lengthening the intake will lower the rpm where peak power is produced, reducing peak power.

Many engines nowadays have stacks of different lengths. On a 4 cylinder skoot there will be 2 short and 2 long. This will have the affect of broadening the rpm where peak power is made, as the 2 cylinders with the short stacks
will have their peak power occur at a higher rpm than the 2 with the longer stacks. Overall peak power may be less than all 4 short stacks, but there will be less of a negative affect on the quality of the powerband.
A few sportbikes have 2 complete sets of stacks. They fit together and provide a long intake tract length up to a certain rpm, then the 2 sets are seperated, allowing the engine to breath thru the shorter stacks. This set-up eliminates the affect of a fixed stack length set-up. NEATO!!

The other aspect of velocity stacks is directly related to their name...VELOCITY.

Air is just like our skoots, at high speeds it does not like to turn quickly. A properly designed stack will have a flaired or bell-mouth shaped entry-way, which will help guide the air in by allowing the air mass to better make the turn into the stack. This simple inclusion straightens the airflow, increasing the velocity(aka speed) and air flow(aka quantity) entering the engine.


Another and often overlooked aspect of a good velocity stack is the stack diameter is not constant. The stack will have a 10 degree angle with it's largest diameter at the top. Again this provides a better entry-way into the stack, allowing a larger quantity to enter the stack, but the smaller lower diameter causes the airflow to accelerate thru this area, increasing velocity.

My skoot is going up on the dyno for it's remap of the V&H 2-1 exhaust. I may try the removal of the stacks.

HOPE THIS HELPS

RACNRAY
 

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Top - I may be interested in this too . . . You ever get up around Quantico?
Sure, I belong to the Band of Brothers Motorcycle Riding Club - we meet at the Mickey Finn Detachment right outside the Main Gate the third Sat of every month at 11:00.
 

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SORRRY, i cannot offer opinions on velocity stacks, but i can offer the facts!!:D

Velocity stacks have many affects on engine performance, and this is accomplished in a few ways.

The total length of the intake system, from the intake valve(s) to the air entranceway determines the rpm where the engine makes peak power. Changing this length will change the shape of the power band, the rpm where peak power is produced and the amount. Shortening the velocity stack length will move the rpm higher where peak power is produced, and may increase peak power. Sometimes there is the "rob from peter to pay paul" consequence. Depending on how short the stack is made, no power may be sacrificed at the lower rpm's. If the stack is too short, then there may be losses in low and midrange power, poorly shaped powerbands will occur. I have seen stacks so short that SEVERE compromises in the powerband occur, with the rpm where peak power occurs just a few rpm from the rev limiter!

Conversely, lengthening the intake will lower the rpm where peak power is produced, reducing peak power.

Many engines nowadays have stacks of different lengths. On a 4 cylinder skoot there will be 2 short and 2 long. This will have the affect of broadening the rpm where peak power is made, as the 2 cylinders with the short stacks
will have their peak power occur at a higher rpm than the 2 with the longer stacks. Overall peak power may be less than all 4 short stacks, but there will be less of a negative affect on the quality of the powerband.
A few sportbikes have 2 complete sets of stacks. They fit together and provide a long intake tract length up to a certain rpm, then the 2 sets are seperated, allowing the engine to breath thru the shorter stacks. This set-up eliminates the affect of a fixed stack length set-up. NEATO!!

The other aspect of velocity stacks is directly related to their name...VELOCITY.

Air is just like our skoots, at high speeds it does not like to turn quickly. A properly designed stack will have a flaired or bell-mouth shaped entry-way, which will help guide the air in by allowing the air mass to better make the turn into the stack. This simple inclusion straightens the airflow, increasing the velocity(aka speed) and air flow(aka quantity) entering the engine.


Another and often overlooked aspect of a good velocity stack is the stack diameter is not constant. The stack will have a 10 degree angle with it's largest diameter at the top. Again this provides a better entry-way into the stack, allowing a larger quantity to enter the stack, but the smaller lower diameter causes the airflow to accelerate thru this area, increasing velocity.

My skoot is going up on the dyno for it's remap of the V&H 2-1 exhaust. I may try the removal of the stacks.

HOPE THIS HELPS

RACNRAY
Great explanation Racnray! Thanks for the info.
 

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Discussion Starter #9
I'm selling mine since I upgraded to a Thunder kit - asking $40 (plus $5 for shipping). Like new (1,037 miles) K&N Air Filter (KA-1709). Includes original packaging & Installation Instructions.
so which design did you go with? i like smooth round one. is this air kit really worth it? i have a fi2000r. do you think it will work for giving the bike enough fuel with the increased air?
 

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so which design did you go with? i like smooth round one. is this air kit really worth it? i have a fi2000r. do you think it will work for giving the bike enough fuel with the increased air?
I went with their stock option (think it was #51010). I have the FI2000R (third pot set to 3.5) along with Cobra Tri-Ovals. I absolutely recommend upgrading....made a very noticeable difference. Bike has more torque and runs cooler. Gas mileage went from avg of 37 to 44 (of course that also included getting the re-programmed ECU).
 

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Great explanation Racnray! Thanks for the info.
Plus 1 You info cleared it up for me. I'd be interested to see what the dyno says if you get a chance

Thanks
 

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Discussion Starter #12
I went with their stock option (think it was #51010). I have the FI2000R (third pot set to 3.5) along with Cobra Tri-Ovals. I absolutely recommend upgrading....made a very noticeable difference. Bike has more torque and runs cooler. Gas mileage went from avg of 37 to 44 (of course that also included getting the re-programmed ECU).
That would be the same set up as me, if I got the air kit. So you use the original right side cover? It's hard to understand how this would work. Did you have to get rid of the left side air box part? So your fi2000r settings are at 4.5-4.5-3.5?
 

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That would be the same set up as me, if I got the air kit. So you use the original right side cover? It's hard to understand how this would work. Did you have to get rid of the left side air box part? So your fi2000r settings are at 4.5-4.5-3.5?
Yes, you keep both right and left side cover, but you trash the right side plastic tunnel underneath the right side cover. You get rid of the OEM filter from the left side, but keep the tunnel on the left side. Thunder provides a mounting plate that goes against the throttle bodies and the right stock cover attaches to the plate. The supplied K&N filter goes between the mounting plate and the right side stock cover. It really lets the bike breathe much better.

I left pot 1 & 2 alone (assume that's 4.5, don't recall) and adjusted the third pot based on research that another forum member did with Cobra and Thunder Mfg. Between the two of them (using Tri-Ovals, FI2000R and the Thunder Air Kit), they arrived at a third pot setting of between 3.0 and 4.0.
 
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