Custom/Hybrid Rok cavitation

[ajmps1]

Its been a slow assembly but I finally got my old sj swapped into my first am ski. I bought the viva tessa rok, its a bit flashy but very impressive paint work. I swapped into it a 83m bore 62t/61x twin 38 mod pipe motor with stock sj pump with 10/16 hooker and it came with a modified worx 206 grate.

Today I finally got it on the water and im getting a slight cavitation at low speeds coming off of plane or intermittently at low speeds. Its just not hooking up everytime the way my rn did. Its hands down a more fun ski to ride but 1 out of 20 its spinning for a second. Anyone have any ideas? Im gonna pull the grate and see how it rides tomorrow without it.

 

[RivMan]

I run mine with a 9/15 hooker and no intake grate. No cavitation issues that I notice.

-Rob

 

[ajmps1]

Thanks man. I think it might be my midshaft seal. Also gonna replace the pump seal as its slightly worn. Cavitaion is more predictable now. If i flat spin or turn real hard then straighten up, im spinning my wheels

 

[HoodbuiltSxR]

Is the hull you are talking about a WDK Rok?

 

[ajmps1]

yup waterdawg kustomz rok. i think i have it figured out, it looks to be a combination of some missing silicone for the pump shoe and a less than stellar pump seal. I was worried about the over hang from the pump shoe, and with good reason apparently, so maybe over the winter i will put a metal shoe in and get a smooth bevel to the bottom of the hull and not make up the gap with silicone as is usually done.

 

[HoodbuiltSxR]

Oic
Glad u figured it out
I'm putting a Rok together too!
Mine came with a aluminum shoe and scope grate.. and they're welded together.. fingers crossed it works..

 

[ajmps1]

oh nice man, thats setup for kawi though isnt it? wanna send me some pics of the pump cavity and scoop? im suspicious of the angle of the scoop i have too. also where is your rear tow loop??

 

[HoodbuiltSxR]

No this one is yamaha with a 144 pump
Il send u a pic after the game, it's almost over
I don't have a tow loop on mine just the front thing

 

[HoodbuiltSxR]

Heres the shoe with scope grate ..

 

[ajmps1]

Oh nice man. You sure its welded in place though? Might just be how it was shortened.

 

[HoodbuiltSxR]

Ya its welded to the shoe.

 

[ajmps1]

Man that kinda sucks. Be careful with the motor mounts. I had to helicoil every hole

 

[ajmps1]

I think part of my issue is also the fact that the hardware size in the rok pump inserts is smaller than the sj hardware. Im gonna try colars on the bolts too to see if it fixes things.

 

[txsuperjetfreak96]

Have you just trying to press pump with your hand to get seal tight against shoe?


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[ajmps1]

Yeah it will seal then but thats not a fix. It needs to be a better seal.

 

[txsuperjetfreak96]

Ive seen guys use ratchet straps to cinch seal tight, dont most all a/m hulls come with smaller inserts for more room to adjust. Shouldnt move after bolts are tightened up


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[ajmps1]

I have been. Keeps moving. I think if the colars havnt fixed it i will use an old pump seal, cut it down and use that to help bump the seal up. It is sealed nicely now though using a nylon colar so we shall see i guess.

 

[txsuperjetfreak96]

Cool


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[gto0209]

I run mine with a 9/15 and no grate with a solas mag and it works awesome, no spin whatsoever.

 

[ajmps1]

What pump shoe?