Velocity stacks, blackbird airbox rubbers and tuning

5 posts in this topic

Hi guys,


I'm taking my X for Dyno tuning in may and am wanting to weigh up all my options for tuning.


Currently I have 

Full Akra system

Power commander 3

K&N filter.


Last time it was setup it had standard headers so the main thing is sorting out the fuelling to suit the exhaust.


I have a couple of questions regarding velocity stacks and the blackbird inlet rubbers after searching around here.


Is it worth changing the airbox inlets?

I have blackbird ones in the shed to try.


Longer velocity stacks, I recall reading one of Wayne's posts about the improvement of torque all over the rev range which I really want.

Are you still running them Wayne? And happy with them?


What velocity stacks are they? Are they standard blackbird ones? Are the blackbird ones different than the X11?


Just trying to sound out the best option to put on the bike before she goes on the roller!


I hope this post ties up some experience everyone has had with these mods, and can be useful for future readers looking for a bit more from the brute that is our beloved X11.



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Full Akra with give you 20bhp more than previously

Fueling will be fine even without the Power Commander. ( X11 fueling seems to be wide band so copes with many mods)

I am stil running the Velocity stacks & BB rubbers. (still happy with them)

Longer Velocity stacks will give you 5ft/lb increase in torque across whole rev range

The Velocity stacks are X11 ones cut & glued 2 sets require to make one long set.

BB rubbers just take the air from a cooler place, check out difference between the two.


As far as I am aware on the X11 a Power commander only smooths out the throtle response, makes it feel  much better thruogh the rev range but does not add singnificant gains in torque or BHP, mind you that was the early ones perhaps there has been progress !


Let us know the results of your dyno run.



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Thank you Wayne, that's very helpful.


Yesterday when fitting new plugs I swapped out the rubbers and tried the BB ones, I liked the top end improvement but it felt a little less punchy low down. 

I'm back to the standard inlets for now.


I will do the velocity stack mod, and I think put the BB rubbers back in before the big tune up!


The Power commander was not something I fitted but came with the bike when I bought it a couple years ago. 

I don't want to run the bike on the BB inlets without it being set up for them seeing as the map is fixed.


Just waiting for my custom end piece to be fabricated for the exhaust and we're good to tune.

I'm going from the ackra headers back to two cans, I just love the look of twin exhausts on the x and the Campbell sidewinders I have sound too good not to fit again!







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I like the twin exhaust,  I purchased a used Akra (X11 one) chopped it up, used the headers coupled to the Honda Y piece, then added my Motad Venom Titanium cans.

It all came together quite well, got the lads where I worked to TIG weld it together. My TIG welding skills where not up to it & I wanted it to look decent.

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first X11  I  owned had a 4 into exhaust and a power commander fitted it never seem right.and having had standard bike since it seem to want to pick up again at around the ton mark but lose torque lower down, but it may be the rambling of a old git

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