Thread: Riva Exhaust System
02-14-2008, 11:11 PM #1
Riva Exhaust System
This new set from Riva is quiet a step compared to the normal Free Flow.
Lets start with a run down of the parts. A complete water box, free flow exhaust pipe and a thru hull fitting.
Why all this stuff.
Well lets start with the original idea back in 07. The 07 Ultra came with two water boxes and 2.5in ID exhaust pipe. In 07 Riva developed the Free Flow which was not more then a J pipe that eliminated the 2nd water box. Cool kit but it required one to cut the thru hull pipe. This altering of a stock part made many shy of doing the kit. Understandable.
Well along came 08 and Kawasaki changed the exhaust system in the Ultra which eliminated the 2nd water box. Doing this made production cost go down and the problem of cross tubing popping off go away. Well Kawi changed the location and shrunk the diameter of the thru hull pipe to maintain low exhaust noises.
Pipe on the Left is the 08 and the one on the right is an 07.
So now that we see the differences we can explain the Riva Kit.
Anyone that has an 08 and wanting to modify their exhaust will need to buy the water box and Free Flow pipe kit.
Lets explain why. The water box fits perfect in the stock water boxes location but is far from the same. Its design was derived from Factory Race Team which does the same configuration on there SC 15F boats. Now the exit pipe on the water box is larger then the 08 exhaust pipe thus needed the larger diameter Free Flow pipe with thru hull fitting. This is great as no cutting or permanent alteration to stock parts is needed.
Now for the cool part. During my visit to Riva I had commented on how it sucks that one has to cut the tail pipe on the 07 models in order to use the Riva Free Flow kit. How that made several people shy away from the kit. So in there development they decided to make the exit thru hull pipe the same length as the required cut stock thru hull.
This is cool so now for those who have not cut their 07 tail pipe and dont want to can order the 07 free flow kit and the thru hull and dont have to alter any stock parts. If an 07 owner wants to improve on their Free Flow they can add the water box and the hardware all matches. So what you have is several parts that one can custom make their own exhaust set up. So those who have 07 will have the most options and those with 08 can have the same performance and no one will have to cut up any stock parts making for easier resale.
The last cool feature of this exhaust system is in the water box. Riva has known for a long time that guys like myself will always push a product to its limit. They realize that the 250 platform invites people to push the envelope of performance. So Riva took extra care in the water box to insure their product will hold the torture we can throw at it. The went with thicker gauge aluminum and extrude pressed the body of the water box. This eliminated the potential for weld points to fail. With Turbo and SC application and modifications, a back fire can happen and the water box is the one to catch it. Riva made sure to reinforce this as to avoid busting the water box and sinking the boat. As often does in highly modified platforms.
They also designed the quality and flow ability to compliment their upcoming Stage 2 kit.
Hope this helps. And dont think for a second I'm not the first in line to get one......lol
02-14-2008, 11:27 PM #2
So the new(Riva) thru hull fitting is the same size as the '07 stock thru hull fitting, DIAMETER that is?
02-15-2008, 12:44 AM #3
Fantastic overvew Skip - as always, well done and thank you
Looks like I will be putting this mod on my "list"
02-15-2008, 07:49 AM #4
And... for a 15f, with the RIVA water box modded, i'll increase something if i use the little exausth part ( pipe of 08 ) ?
Last edited by hsdforever; 02-15-2008 at 11:36 AM.
02-15-2008, 10:56 AM #5
02-15-2008, 02:25 PM #6
02-15-2008, 05:36 PM #7
so how much, and what are the gains? if any. wait and see what i build for the ultra. whheeee whhiiii.
02-15-2008, 05:57 PM #8
With those big ass cast iron exhaust manifolds it has, just the weight savings with a set of your headers would be great. I for one am happy that you decided to work up a set for the Ultra after doing some for the Seadoo.
02-15-2008, 06:00 PM #9
02-15-2008, 06:09 PM #10
I have no idea if this motor will react to a set of headers like the Seadoo does, but i'd damn sure like to find out.
Other than working them over the supercharger, you should have a straight shot all the way back to the exhaust outlet at the rear of the hull. If you get those results, (200 more rpm) it sounds pretty sweet
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