Which impeller to use of these 2...

[Cannibal]

So I'm putting together my pump and after getting the bearings on I need to decide on an impeller. I have 2 here in front of me, one is a Skat 9-17 and the other is a Skat 14.5-18.5 that is cut back to 1mm from the blades. I can also put the 9-17 in the lathe and take off 3mm if that makes a difference.

Here's my setup:

Stock port 701 .5mm over with Wiseco pistons, Riva head w/35cc domes, B Pipe with Mod chamber, single BlackJack 44mm carb, and MSD Total Loss single channel digital (the one with Hole Shot). The pump has been blue-printed. The reduction nozzle has been bored a little and the siphon port removed, welded and ground smooth. I am also running a Pro-Tec steering nozzle.

Me:

I'm about 5'7" and 235lbs. I ride mostly lakes, but would like to get into surf a little too (then maybe a little more if I like it as I suspect I will). I always seem to fall mostly when I do something that slows me down and my ski does not have enough to get my ass on a plane fast enough, so I want a lot of grunt so I'm thinking the 9-17, but ????

I do not have the coin for a hooker, even after selling these 2, so that's not an option.

Thanks,
Steve

 

[Kirv]

it sounds like you're more into freeride than racing, go with the lower 9-17. you'd need some serious motor to make that high pitch prop pull hard down low.

don't know about the cutback effects, so hopefully someone who knows impellers can chime in.

nice pump setup.

 

[keefer]

Try them both and see which one gives the best all around performance and the least cavitation for your setup & riding style. Dropping the pump and swapping props does not take that long. You might look for a deal on a Skat swirl or a Solas Concord, they will give much better performance than the old style blade & hub designs.

 

[WAB]

Those Skat 14.5/18.5 are great props.
Take out the pump and test fit them both. use a feeler guage to see which is a tighter fit in the pump's wear ring.

 

[orangefinger]

9/17 is the former 14/17 which is an overall good impeller

 

[kevbo]

The 9-17 is very good with a stock cyl and B-pipe, dont waste your time cutting it back. The rev limit will need to be raised if stock ignition is used. You should be able to turn around 6800 rpm static with an 85mm nozzle. Any more load will kill acceleration.

 

[Cannibal]

Well, I'll try the 9/17 first then. I didn't know where the limit of that impeller was. The 14.5/18.5 came with the ski. Pretty stock 650, just Pro-Tec lightened flywheel and the BlackJack carb. The side of the hood lip was clearanced for dry pipe, so I think it was set up for speed. I didn't know if my modifications were enough to make the 14.5/18.5 rip or not.

Thanks All,
Steve

 

[brett]

9/17 works great on my sn. stock 61x with sizzler pipe.

 

[kevbo]

A good redline for the Yamaha 144 pump is around 7200rpm. At low speeds the hottest 760, or bigbore for that matter, cannot pull an old 9-17 that fast. These props work very well overall, a repitched concord runs smoother and primes faster.

 

[Cannibal]

Maybe before next summer I'll be able to (read: "my wife will let me") sell both of these and get one of the famous Hookers.