A few of you have been waiting for this so here are my results after having installed the Motomaxx velocity stacks as found from their Facebook page here
Refer my hyperlinked signature for listing of other mods done to my bike; individual result will vary depending on level of mods to your bike. Unfortunately for me, this modification did not return a benefit other than a learning experience. Credit to @_Yamato
for his contributions and of testing the concepts of velocity stacks, and I recommend reading his post on the subject here
. Also a shout out to @Oyabun
for his input on the subject also; without the two of you guys for inspiration I don't think this would've eventuated.
So these stacks are a nice bit of kit, milled from solid blocks of billet aluminium.
Side-by-side you can see how there was expectation from the change in shape and height that they would flow better than factory; based on the knowledge that wider means more flow and shorter better for higher rpm power.
Installation is for the more technically minded. It requires removal of knee panels, front fairings, fuel tank, and airbox & throttle bodies (as one). Separating the main halves of the airbox you then just undo three screws for the v'stack housing. The stacks just twist out, and you twist the new ones in; then re-assemble everything back together.
Of note, the ones that I received did have a small 0.5mm lip on the bottom end that required removal using a rotary too. This was notified to the company, so hopefully future versions have this corrected.
I had previously had a run back in July for a base figure. By the time I received the stacks for installation, I had since replaced the tyres due wear. So when the dyno was spun up and we saw that the returned figures were actually less
than the base run, there was some concern. So out with the new and back in with the old factory velocity stacks to get a new base line. Comparative dyno graph result below, as you can see, very little difference between factory and aftermarket; like ~1hp or less which can easily be attributed to environmental & other factors.
Be aware however that my bike already being quite modified, that it may be a case it has reached the capable limits of flow. So I'm not saying these stacks are of no benefit, just in the scenario given they did not return desired results. Maybe if my bike had ported and polished heads to compliment the other modifications, that these would then be the key to releasing further potential.
Another key element is that the company has developed these stacks in response to seeing that the factory stacks in many markets have a restrictor plate in place... if looking down the velocity stack looks like the below, you got the restricted version.
Easy, cheap win is to order the factory stacks from another country. In the parts catalogue they are listed as P/N 17251-MGZ-D00 (left) & 17252-MGZ-D00 (right), they also come with a country dependent serial code, U and 2U are for Australia of which being my country I know are unrestricted funnel models. But if you like a bit of bling, or maybe the price plus shipping doesn't work favourable, there's nothing wrong with grabbing a set of the Motomaxx velocity stacks.
If you're interested in this product, simply get in contact with Motomaxx via their Facebook page.