How to create your own velocity stacks on a Yamaha 230 series boat

[Ronnie]

This is a simple and inexpensive mod for those that think that the stock set up restricts air flow to much but don’t want to spend $50 on aftermarket velocity stacks.

First you have to take the assembly with the flame arrestors off the engine. You will need a Phillips screw driver to remove the two screws on the air filter cover and an Allen wrench to remove the four Allen bolts holding the assembly onto th engine.



Second determine if you want to preserve the parts of the assembly for future reinstallation or not.

Third get the rubber connectors that are installed under the flame arrestor elements out of the assembly.

If you don’t care about damaging the rest of the assembly you can drill or cut the 16 rivets out which hold the assembly together.


If you want to preserve the rest of the assembly you can use dremel to carefully cut the rivet heads off or simply use a small flat head screw driver to pull the rubber boots/connectors out of the assembly. Reassembly may rerivetimg or the use of nuts and bolts.

Once the rubber connectors/boots are free from the rest of the assembly, clean them off and install them in the same orientation they would be if they were still in the assembly (they slip on and no clamps are used or needed). These are the velocity stacks.



The cleanable / reusable Air filter seems by Riva and r&d act as flame arrestors for those of you who want to stay legal.

This pic is of my other waverunner with a 160 hp 1,052 cc engine which has the r&d velocity stacks ($50) and air filter ($100ish) installed on it (with the air filter tilted to show the element).

This pic shows the differences in size of the stock elements with the larger of the two from the fx 160. The rest of the pics are of the mod being performed on a 140 hp 992 cc mr1 engine in an fx 140. Both of these engines were installed in the 230 series boats.

 

[Scott griffith]

Did you see any difference when you did this

 

[Ronnie]

Not a thing but i boat at sea level most of the time so i believe im being limited by the yamaha ecu settings. Still i think that doing such a mod is worth the effort just to get the engine to breath better even though this cant be proven nor is tracked anywhere.

 

[Jgorm]

I wonder if there is any benefit from leaving them in. The filter will create laminar air flow, but that might not even matter. If you don't get more rpm / speed, is probably not worth the time. My experience is that reducing a non bottle neck produces little gain, like installing a larger throttle body on a car where the bottleneck is at the heads. I'd also be a bit worried about sucking in a bolt or something. Normally there are no fasteners in the intake track.

 

[Ronnie]

I replaced the stock flame arrestors in my 06 sx 230 ho with r&d velocity stacks and air filters, I also did the mod on both of my 06 waverunners before transferring the stacks to them from the boat when I sold it. I never noticed any performance gain or loss, no noticeable difference in sound either. I’m not anymore worried about sucking up anything then I am with an entirely stock system, there are no loose bolts or items in or around the air filter box. At the same time, I’m not advocating that anyone do this or install aftermarket stacks or sleeves, just showing everyone an alternative. Recall that Some guys run without an air filter and others swear by the air Intake modification on the 1.8 liter engines (which by the way is just a sleeve which replaces a single flame arrestor elememt). the engines may/should get more air easier but it if they are prevented from using the extra air the aftermarket stacks are definitely not worth the $50 they cost, with this mod you accomplish the same thing for free. Again I didn’t see a performance gain but others that boat at different altitudes May and it’s hard to believe that the engines are not getting more air.