The other day I was racing my friends RXP. We are neck and neck out of the hole but my Yamaha explodes on excelleration and gets to it's top end faster than he can. So at about a 100 yard race I am at least 3 boat lengths ahead of him! The problem is once he reaches top end I no longer walk away from him. We have identical top end speeds! Below are my current mods and I do not want major mods to the engine. Is there anything I can do "bolt on" to get more top end?? We were riding in glassy conditions at sea level, water temp around 80 degs. (we ride in a lot of chop to) Another thing is we are only reaching top end speeds around GPS 65 mph @ 7340 rpm's. My mods out run a Riva stage 1 kit and it's spec'd at 70 mph??? What's up with that...

Riva EFI
Riva performance ride plate
Riva performance trim tabs
Stepped sponsons
Riva race flame arrestor
Reed stuffers
Riva pump seal kit
Riva intake grate
Solas 13/19 impeller
GPR 87mm exit nozzle
D- plate

It smokes....just hungry for more top end!

This message has been edited. Last edited by: GPR FL,

I would try a Nujet 6.5 or Solas 14\20 out of the box then send it to carl & have it de-pitched accordingly.The Nujet is my favorite but you must have a good tight liner fit to reap the benifits on top end.

To get more top end, you need to swap that 13/19 for a Nu-Jet 6.5 Pro or a 14/20 based impeller. But, you'll lose some holeshot. To make up for it, do Fercho's Jetworks valve waterbox mod. The impeller will have to be custom-pitched to your Waverunner, especially after the Jetworks mod. I like Carl @ Island Racing for prop work, but there are others. I would also recommend either an aftermarket or stock-milled pump gas head. Additional options are the Island Racing angle mod and skeg removal on your ride plate which is usually good for 1.5 MPH on glass and wing mod on your intake grate which is good for .5 MPH. It's tough to get both holeshot and top speed, but it can be done. Right now, my holeshot is dead even with my friend's RXP, but I have 3 MPH on him on top. Unfortunately, he just received his Stage I kit. So, I have more work to do.

Thanks. I will give that a try. So how is a riva stage 1 kit hitting 70mph??? I live in an ideal place to hit 70 and haven't ran across a PWC that can beat me yet.

they do their testing on a lake that is downhill

LOL I need to find that lake so I can post 72mph!

What about a free flow for added top end?? Also what have you guys heard about the RXP stage 1 kit. My friend will probably be getting one. Will I be in trouble?

"free flow" - nope, by itself it will probably slow you down - get a Nujet

The freeflow tube is for added holeshot and is recommended when installing the Jetworks mod. It can actually slow you down on top.

Yes, you're in trouble. Riva has figured out how to really make money by selling arms to both sides.

Head, Nu-jet 6.5 setback and de-pitched or a solas 14/20 de-pitched, remove skegs from rideplate. Call CArl @Island for a good prop. Your biggest problem is the 13/19 based props just don't have top end. If you add a pump gas head it will give you more grunt to swing a bigger prop.

This message has been edited. Last edited by: VOODOO,

Would that be downhill at niagra falls.HAH!

Some idiot tried to commit suicide this summer and jumped off the falls - the only thing is he made it down OK.

Go figure some people have all the luck!

Must have been the guy with the 90 MPH RXP!

The NuJet brings good mid and top speed but if you are dead even out of the hole with the RXP now,the RXP will hole shot you with the NuJet unless you go with the plastic pump liner and even then i would be "iffy". Get a 150 psi head and Jetworks mod (Fercho),and depitched 14/20,maybe an I Cut from Island Racing,that RXP will be gone.You are spinning 7340 rpm,thats alot,you need more prop.Have you tried pulling the washer out yet?

Forgive the ignorance...what washers?

The washer that is under the prop. Removing this washer will set it back and give you better hookup and reduce RPMs. If you remove this washer, it may make it more difficult to remove the prop later.

quote:

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Originally posted by Nino:
The washer that is under the prop. Removing this washer will set it back and give you better hookup and reduce RPMs. If you remove this washer, it may make it more difficult to remove the prop later.

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Nino.. Where do you ride in St Pete? That is where I ride!

Hey RXPeater - I ride at Fort DeSoto or Seminole Lake. I want to get my GPR handling right so I can race CC near the Skyway. I would like to pick up a used pair of R&D sponsons. Where do you ride?

quote:

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Originally posted by RXPeater:
The other day I was racing my friends RXP. We are neck and neck out of the hole but my Yamaha explodes on excelleration and gets to it's top end faster than he can. So at about a 100 yard race I am at least 3 boat lengths ahead of him! The problem is once he reaches top end I no longer walk away from him. We have identical top end speeds! Below are my current mods and I do not want major mods to the engine. Is there anything I can do "bolt on" to get more top end?? We were riding in glassy conditions at sea level, water temp around 80 degs. (we ride in a lot of chop to) Another thing is we are only reaching top end speeds around GPS 65 mph @ 7340 rpm's. My mods out run a Riva stage 1 kit and it's spec'd at 70 mph??? What's up with that...

Riva EFI
Riva performance ride plate
Riva performance trim tabs
Stepped sponsons
Riva race flame arrestor
Reed stuffers
Riva pump seal kit
Riva intake grate
Solas 13/19 impeller
GPR 87mm exit nozzle
D- plate

It smokes....just hungry for more top end!

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what do you have your EFI# set to ? i have the same set up as you but i have the heads

KNR- My efi settings are 3-9-2-6. What are yours set to and what kind of top end speeds are you hitting??

Nino- I ride around For Desoto as well. We usually put in on the left hand side of the bridge right before Tierra Verda Marina. I have wanted to go out to Seminole lake. What are the conditions usually like there and where is the best place to put in? Thanks again for everyones input this is a great forum with very knowledgable people.