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Discussion Starter · #1 ·
I opened the airbox of an 05 today and noticed that the difference between the outside velocity stacks and the center ones was ALOT greater than in the past. I also noticed a curve to the center two stacks. Has anybody converted over to all super short stacks? Did you gain top end/lose bottom end? I was going to have a machinist buddy make a copy of the Attack billet stacks that would fit an 05 but noticed that they would be considerably longer than the outside stock stacks.

Any thoughts?

Baldy
 

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My thought is that the stacks in the K5 are a compromise.
The long and curved ones seem to be that way to get out into the air flow.
This air box seems to have a large protrusion in it that the two centre ones are trying to avoid.
The two short ones are so short to make up for the long ones. They don't look ideal either, no progressive lip.

If you are making them all the same (and hopefully the two centre ones flow correctly) then
set the height to target the rpm range you are interested in.

 

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at Road America, during the yosh seminar, Doug adressed this point.
He said that inside the airbox, the flow is different closer to the sides, than in the middle, and that is ONE reason for different length stacks.
as well as giving a better overall torque curve, but he seemed to imply that interior airflow was a more direct reason.

Use of different lengths, was in concert with cam timing, exhaust spec, etc.
 

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I installed my Factory Pro velocity stacks last week. But it was raining at Barber on Saturday, so I haven't ridden with them yet.
 

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Discussion Starter · #6 ·
Thanks for the replies. I knew that Factory has some but some of his rhetoric and stuff make me wonder if sometimes he's just a snake oil salesman. I know his stuff was good back in the day when I used his jet kit on my 92 GSXR1100.

Stuart, you wouldn't happen to have a pic of those beauties would you? The one on Factory's site doesn't show how well the mouth is designed.

Baldy
 

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That's why you have to talk to him, so see which ways he went before he settled on something. I did that on the ones for the R1, and his were better than the Graves though they defied conventional design (they were all long vs 2 shorts like Graves).

Maybe you can get him to throw in a bottle of snake oil for free


Keep you BS meter on during the convo.
 

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at Road America, during the yosh seminar, Doug adressed this point.
He said that inside the airbox, the flow is different closer to the sides, than in the middle, and that is ONE reason for different length stacks.
as well as giving a better overall torque curve, but he seemed to imply that interior airflow was a more direct reason.

Use of different lengths, was in concert with cam timing, exhaust spec, etc.
Thanks for the interesting info. You will probably need to mimic the OEM design here for best results, or maybe a new air box.
If I was changing the stacks in a K5 air box I would definitely use the dyno.
 

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Marc's a super nice guy...I added these to my FI modification...Fit really well and no airbox modification like i had with my Attack stacks..

 

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I'm no expert, but I'm not going to rush out and buy the stacks cuz the second design (minus the shiny factor) is cheaper to build than the first. Why would the factory build these diff twisty things when it would have been cheaper to make similiar straight pieces (like Factory Pros)? It just doesn't add up. I could be wrong, but the stock ones are prob better. What do you think, am I hozed?
 

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I'm no expert, but I'm not going to rush out and buy the stacks cuz the second design (minus the shiny factor) is cheaper to build than the first. Why would the factory build these diff twisty things when it would have been cheaper to make similiar straight pieces (like Factory Pros)? It just doesn't add up. I could be wrong, but the stock ones are prob better. What do you think, am I hozed?


If i remember correctly the 01-04 1000 all had long and were slotted at the bottom.And some like myself changed to all 4 short. I had the 750s and the attack stacks all in which changed the attuide of the bike.For me it was improvement in areas of the RPM.(after remapped)I do several trackdays and mainly focus on that so it was great for me.What im trying to say is im sure the same goes for the 05..They have to design the bike to be rideable for all.Some modification you do to the bike have to suit you..Just like the pipe for instance it was designed for the 05 but you can get a different one and it will changed the machine.Now will it suit you..Some do it for the numbers some do it for the change...Do ya kinda get what im saying.
 

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YA! some thing worth reading.
Now back to the regularly scheduled program.
Any body got some pics of a blue and white 05 1000 with a yosh slip on?
 

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I prefer either the Yoshimura stacks (several different sizes) of the Attack stacks. Remember any changes in stack height or placement requires a tune job.
 

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You are missing the point, the older air boxes didn't have the stacks right up against the side
like the K5 one does, this is why they are curved, pointing at the center and tall enough to
clear the two protrusions circled in red.

If I was going to mod this air box I would try to cut out those protrusions to clean up the air flow
around the straight stacks that I would be installing.

 

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You are missing the point, the older air boxes didn't have the stacks right up against the side
like the K5 one does, this is why they are curved, pointing at the center and tall enough to
clear the two protrusions circled in red.

If I was going to mod this air box I would try to cut out those protrusions to clean up the air flow
around the straight stacks that I would be installing.
this is exactly what i did with the 02 airbox and im running 4 short stacks and its an improvement over stock setup with only 2.5hp difference... a buddy of mine has the billet stacks and saw a diff of 2hp ... plastic or metal it doesnt matter its going in the airbox.. its the size of the stack you should worry about and filter and volume of air in the box...

i had a carbon box on their as well for testing purposed and it was only a 3hp difference.... $600+ for carbon box, glad i passed on that one... stock box is just fine with minor mods as you pointed out and shorter plastic stacks and new bmc race filter
 

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Would be nice to see a comparison back to back dyno run from stock to the Factory Pro. Since the K5 airbox is different from previous 1K models I'm curious if the internal changes to the box and the need for the curved and short outside stock stacks makes any difference, no slots either this year.
 
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