Custom/Hybrid effect of spacing impeller away from pump stator.

[madness maker]

Has anyone have any experience with adding spacers behind the impeller on a yami 144 pump? in our glass freak i am running a 10/16 hooker with a ported 61x 62t with the basics (head,msd cdi,lightend flywheel,reeds,b mod pipe,stock 38's, scat mag pump ,stubby cone and 85mm nozzle) ski runs good, but feels like its a bit over propped on the bottom end, not looking to buy another impeller or repitch,as prob going to a bb over the winter. i thought i read somewhere about spacing the impeller away from the stator to "loosen" the pump up slightly.. im hoping doing so may get it up on the pipe faster on the low end, i have seen 1mm spacers avail. but wasnt sure where to start, 1mm 2, or 3mm etc? or how much of an effect per mm of spacing. (currently the prop hub is real tight up against the pump center bearing hsg) thanks for any info.

 

[GIL]

I have played with this exact thing more than I care to talk about. LOL

Now to answer your question. Yes-moving the prop forward does allow everything to 'spool up' faster. As with all things though-there IS a fine line. Art at BlackJack Performance actually makes/has spacers to do exactly this. I to am running a 10/16 Hooker and I found my happy medium to be running the stk Yamaha prop washer and one of Art's spacers
that I believe is 2mm thick. I tried as much as 10mm forward spacing to the other extreme of no washers at all.

IMO-you want your engine to 'get on the pipe' as fast as possible without blowing the prop loose therefore everyones setup is going to be different.

 

[sportfish258]

I'm playing in the same sand box . I understand moving the prop further from the stator reduces pump pressure allowing the motor to spool up quicker.

My question is will you still retain the same hook up in the white water if add spacers behind the prop?


I recently tried my 8 vain mag with a limited Gomez 701. Feel like i lost a little on the bottom Going from a stock pump c-75 combo to the mag. I'm about 85 on the nozzle. Might try an 87 ?

 

[kevbo]

Send the impeller back home for repitching.

 

[munki63]

Prop pitch is all about what the rider wants but even on a BB with all the bells and whistles I found the 10/16 to be over pitched... I think there may be a general misconception that between the 9/15, 10/16, 11/17 you can cover any set-up, If you still wanted to run a hooker you should drop it down to the 9/15 IMO... I tried all 3 on my BB and ended up leaving the hookers and getting a solstice for myself it worked much better, and I believe the hooker is set-back 2-4mm so you could get away with spacing forward 2-4mm

 

[JetManiac]

Send the impeller back home for repitching.

This is the preferred solution. Minor amounts of impeller shimming can correct improper pitch but at the expense of efficiency especially with larger washers. Better to use larger pump nozzle and/or smaller pump cone for tuning.

Oem impeller washer is 2mm. We have different thickness SS washers available for shimming.

 

[Pablo]

This is the preferred solution. Minor amounts of impeller shimming can correct improper pitch but at the expense of efficiency especially with larger washers. Better to use larger pump nozzle and/or smaller pump cone for tuning.

Oem impeller washer is 2mm. We have different thickness SS washers available for shimming.

X2. Grab a two extra nozzles. Have 85, 86, 87 on hand and pump cones. just going down in pump cone size helps and if youve done that then upsize ur nozzle. We've gone as large as 87 mm on OEM. Some of the beefier AM nozzles may go 88 or more.

 

[munki63]

Or just get the propper impeller for your setup, Call Impros

 

[madness maker]

thanks for the info, going to try shimming slighty for now and give it try this wkd, once i get settled on a new motor, i will invest some time in proper impeller choice for new setup.

 

[geraban19]

Ive never heard about it.