Spinning my prop. problem or pitched too low?

[Project Ski]

Not sure if i have a pump problem or im just pitched too low.

Have an 85mm flat top Lamey 6mm stroker , b pipe, 175 PSI, dual Novi 46,

standard yamaha 144 pump with tbm supercone, skat 13-17 swirl 3mm cutback. and nozzle at 85mm

Cant get past 10 mph or so without spinning the prop unless i really feather the gas. you can hear the motor rev up but i dont gain any speed.

 

[Crab]

Toploader? I'll bet you need more prop or have an air leak.

 

[Kennay]

13-17 swirl? A nearly stock SJ could pull that good. I am going to go with you need a mag pump for a freaking 6mm Lamey stroker. There is one for sale in the FS forum now I think.

 

[sflsurfrider]

13-17 swirl? A nearly stock SJ could pull that good. I am going to go with you need a mag pump for a freaking 6mm Lamey stroker. There is one for sale in the FS forum now I think.

not necessarily. ive seen stock 13/17 concordes pull jus fine with no cavitation on lamey strokers.

you probably have a leak in your pump shoe seal or intermediate housing.

not too sure about the tbm cone, though.

 

[D-Roc]

are you using a c-75 swirl with that tbm supercone? it works on my buddies 5mil team scream with race gas.

 

[Mouthfulloflake]

just as a comparison,

I was spinning a 12/15 concord with a WW cone, and a nozzle bored to 87MM with a 650 with a head and a pipe.

with that size nozzle, and a cone, and that much power, I could easily see him spinning that impeller.

 

[D-Roc]

my solas prop would spin or feel like it was slipping out of the hole with 85.5 nozzle and wetwolf cone, i but the stock cone back in and it helped a little bit. i then went with c-75 swirl and tbm supercone. he needs to find out if it is indeed slipping or just cavitating from an airleak.

 

[Kennay]

not necessarily. ive seen stock 13/17 concordes pull jus fine with no cavitation on lamey strokers.

you probably have a leak in your pump shoe seal or intermediate housing.

not too sure about the tbm cone, though.

I was kiddin'

If I had enough money to get a huge sroker engine, I would at least get a mag pump though

 

[Project Ski]

It is a c75 prop. The only place i can see it leaking from is the intermediate shaft. The pump show is freshaly silicones in and im pretty sure i did a good job sealing it up.

I was thinking the nozzle may be bored too far. will any 144 yamaha nozzle bolt up properly? Ill try going back to 82-83mm stock and see if it helps. Thanks for the suggestions. Keep them coming. It was really annoying to not be able to tune the ski in carb wise becaseu i was just spinning the pump.

I hope i just have way too much power for the thing but im guessing its just a leak or error in nozzle size.

 

[Mouthfulloflake]

swap the TBM cone back to stock ( assuming its smaller than stock) that helped my 87mm nozzle alot.

 

[Project Ski]

its not just the end cone, its the full tbm supercone pump stuffer. I changed to the largest of the 3 cones that come with the setup and it didnt help all that much

 

[Project Ski]

Ive been told an airleak at the midshaft assembly in in the engine compartment would actually work just the opposite. It would fill my hull up with water rather then sucking air intot he pump. So it sounds like i am either wayyy underpropped or my nozzle is too big. i dontthink 85mm is so huge it would cause this type of problem. Stock is 82-83 isnt it?

Does anyone have a tall pitched c75 they are willing to part with?

 

[D-Roc]

it would possibly fill your hull if you where floating. when the motor is running it would leak air into the pump shoe area before the pump where there is suction.

 

[Big Kahuna]

how about the round seal between the pump and pump shoe........... that will cause a problem. also trash in your grate, or a bent blade on your prop.

 

[Project Ski]

Nothing in the grate and the prop is brandnew.

I think you guys found the problem for me. Speaking to Gil on the phone i relaized i dont have a seal in place between my shoe and the pump. Its just bolted together with that metal lip tokeep it alligned. I bought the pump used and the shoe seperate and didnt know there was a foam seal between the 2.

Im probably sucking a ton of air from my pump cavity through that gap. Although by eye, when bolting it together it presses together really tight.

 

[Project Ski]

droc, i was told the EXACT opposite of what you are saying. while idling aroudn it will suck air out of the engine compartment, when under speed the pump cavity gets pressureized and pushes water ino any spaces, including toward the engine compartment.

 

[D-Roc]

that could very well be. it would make sence that a combination of throttle and speed could make it either suck air or force water into the hull. it would be interesting to see it happening. you would think that it would be hard to force water backwards into the tube but maybe with an aggressive scoop grate the pump inlet grabs more water then the pump can actually pump. this could make for some wierd intermitant slippage/cavitation.