What Prop

[Dienewk]

Hi All
Firstly awesome sight it?s been a great help for me as a new time boat owner.

My purchase was a crusader hull (14.5 foot) with a V4 2stroke evinrude 1977
Got this last summer and it lasted the summer before dropping compression in a cylinder so i got her rebuilt over the winter, took it out the other week end and it ran great for the first tank of fuel then a bit doggy after and kept stalling when trying to pull up a skier, i have put this down to me being a bit to keen with the oil mix.

My main question is the boat struggles to pull up a single skier(we have gotten fatter since the teenage skiing years) so wondering if a prop change would help, my prop has no details on it at all, I may need to take it in and have it measured.

Any suggestions on correct prop would be great, the boat is pretty quick so I wouldn?t mind dropping some speed to get more pull.

Cheers
Tim in Oz

 

[steelespike]

Re: What Prop

Need hp of the motor. Also the present max rpm and speed.Prop size is sometimes under the prop nut.Wouldn't hurt to have a description of boat, its weight and typical load when skiing.Do you trim in at the start when pulling a skier?Oil mix won't affect performance unless your skimping on the oil, which will ruin your motor.Be sure your running at at least 50:1.
Being doggy and stalling under acceleration could be a fuel supply problem.If it is running lean it could be the reason for the previous failure.
and if not solved another failure could be in your future.
Couild be just a weak fuel pump or old fuel lines or connectors leaking air.
If squeezing the primer bulb helps could be an indication of a weak pump.

 

[Dienewk]

Re: What Prop

Sorry steele it was a bit poor on info

its a 115hp motor, the rpms i have no idea about as i dont have a tach, i will look into the weight of the boat.

so a 50/1 is a must and a little bit more oil doesnt hurt?
ok so i wont drop the mix

its just a pisser cause when this boat runs well its a cracker.

if it is stally i pull up the warm up lever to build the revs, drop the lever and hit it and this can usually get her going but its not the ideal way to try to pull skiers up or to drive my boat. at the moment its kinda taking the fun out of boating, i spend more time starting that driving it.

thanks for the reply so far

 

[Bifflefan]

Re: What Prop

50:1 is the correct ratio. no less or more.
As for the prop a 15p should pull a skier up good, i use a 17p on a 16' glass boat that does ok, a 15 would be better but you also need a tach so not to over rev the motor.
First thing id do tho is find out why its bogging. When you rebuilt it were that carbs done also? is the timing correct? And so on. It sould as if you have some other issue, fix that then work on the prop after you have tried it again when its running good.
By running good i mean idles in gear i the water all the time, and, well is running good.

 

[steelespike]

Re: What Prop

You might try hitting the choke a little as you try to accelerate.
Again if that helps it indicates a lean condition.The carbs have fixed high speed and idle speed jets.so adsjustment isn't possible.There is a thumb screw on what I'll call the throttle arm.It appears you can adjust the idle speed there.Have someone operate the throttle at the control as you observe
the operation you should be able to tell the trhrottle stop screw.
Increase the idle the least amount possible as it is hard on the clutch dog to shift at too high a idle.A tach would be handy.A tiny tach is about $40 and
an easy install.Will also fit any 4 cylinder 2 stroke.They have a web site
be sure to read the info carefully.

 

[Dienewk]

Re: What Prop

Thanks guys

perhaps this Question might have to be moved till i sort out the engine issue


the odd things (and the reason i started to blame my miX) was it ran like a dream for that first tank of juice, then it started to stall and bog down. this used to happen before the rebuild so i guess the light bulb should have came on then.

i will take her out on the weekend and looking into those few fuel things with
the primer and the choke

Oh and yes i do own a manual lol

 

[Dienewk]

Re: What Prop

hey guys got my Tacho ordered it is a digital jobby that clicks onto a plug lead its the tiny tach, it should do the job.

while idling in the water what should it idle at?

also in answer to a question up the top the carbs where NOT rebuilt in the engine rebuild