Ok got her on the water.

[Rollinunknown]

Ok current prop is a 12-1/2x13 Very powerful whole shot!

But rpm is at 4450 i can get 5000 if i tilt it way up but but it slows the boat down and cavates .

My tach is brand new Teleflex and is set on 6pole's Like Joe says and will idle around 750-1000 rpm .

So as of right now i dont think the tach is off

I would like to get some more speed for sure and its ok to run the motor at 5500 rpms with out hurting it?

What prop would i be safe with ?

Theres one for sale local thats a 17pitch but im not sure if a 17 would be to much or not ? they want 75 buck's

This is a 1996 Evinrude 48 SPL on a 1966 MFG Beachcomber tri hull.
Top speed right now maybe 25 ish range who knows for sure.


Thanks ahead of time guys for the help . Rob

also i would like to add .... 1966 AND ZERO LEAKS whew.... i was a little worried but shes was dry as a bone.

 

[airdvr1227]

Re: Ok got her on the water.

You're running a 13 pitch prop now. Increasing the pitch will lower the RPM's.

 

[Rollinunknown]

Re: Ok got her on the water.

i thought the higher the pitch the better for top end more rpm?

like a 17 will give me more rpm ?

your saying a 17 will lower my rpms and give me more hole shot?

 

[airdvr1227]

Re: Ok got her on the water.

No...and I'm not an expert. My take on it is lower pitch = higher RPM and more low end torque...kind of like low gear. If you increase the pitch you lower the RPM and decrease the torque.

 

[steelespike]

Re: Ok got her on the water.

Very basically lower pitch(smaller number) increases rpm and power may limit top speed depending on the previous prop.Higher pitch less rpm/power, more speed if motor can turn up to its rated rpm.
Your 13" is in the middle of the chart.
What is the size and dry weight of the boat?
Does the boat respond to trim out/up bow should come up and speed increase,or does the boat lay down like it is glued to the water?
The antivent plate just above the prop should be visable on plane?
Do the throttle plates open all the way? motor in good tune.
Bottom clean and smooth? Does the motor have a hydrofoil on it?

 

[Rollinunknown]

Re: Ok got her on the water.

ok motor is in tip top shape 150 psi carbs dead on every thing is great.

Now the hull ive got no ideal it jumps up on plane in 2-4 secs its almost instant the bow comes up then lays down as good as it gets for a tri hull boat .. the bow is still a very small amount up slightly tilted.

I dont know if you guys are familiar with the Touch trim on evinrudes but i have the motor set at the half mark on 0 and 1 its on the half mark.

If i tilt it down all-the way it drags and if i come up a bit it cavatates but again it runs great i just want a little more speed and since its not no were near 5500 i was thinking i dont need the whole shot that it has i would like a bit more top speed.

 

[steelespike]

Re: Ok got her on the water.

Problem is your rpm is 4450 you need 1000 rpm more thats about 5 inches decrease in pitch thats at 200 rpm for each 1" decrease in pitch.that would put you at about 8" pitch Thats below what you would need to push a big pontoon boat.
So something is up we need your speed to try to tell where the problem is.
Is it manual trim? As you raise the trim the boat shoulds get faster and the bow should stay up some once it settles after planing.
about 2/3 of the boat in the water.If the steering is forward the spray should be behind you.Still need to know the size of the boat.and speed;perhaps you could borrow a gps.

 

[Rollinunknown]

Re: Ok got her on the water.

ok so the tach should be set on the 6pole position for sure ?
ill get the GPS speed soon thanks man.

and the spray is behind me for sure and i do have forward steering .

If i trim it up just a little its cavatates bad so i have it set just below that point and it still shoots out of the whole like a bat out of hell .Il try to get a video of how good it jumps up and takes off im meeting a few buddy's in the morning for fishing.

 

[steelespike]

Re: Ok got her on the water.

Ok, spray sounds good.
I don't know the tach setting.
Your idle seems ok.
1, Check that the antivent plate is visable when on plane.
Maybe a video. This setting could net 2 to 3 mph in the extreme.
2, size and weight of boat?
3, Prop in good shape?

 

[Rollinunknown]

Re: Ok got her on the water.

ok just for the heck of it i just put her in the water down the street...

Well it seams like it will turn 4500-4600 and hit the rev limiter .....

The tach has to be right i mean it idles at 750-800 rpm ...

Its like it his a rev limiter then cuts power for 1/2 sec then comes back ....

Maybe my tach thats brand new is not setup right ?

I have it hooked to the Grey wire coming off the motor

Is there anyway i can check my motors rpm's for sure i would be sick if i was over reving it........... You would think the 75 dollar teleflex guage from bass pro would work fine but who knows ... ive heard put it on 5-pulse and someone says 6-pulse .......

The anti-vent plate is 1 inch higher then the bottom of the boat out of the water.

I think im over reving the motor and the tach is wrong .....

This is what i bought http://www.basspro.com/webapp/wcs/stores/servlet/Product_10151_-1_10001_10200202____SearchResults

Only reason i went with bass pro is do to i needed it TODAY....

At this point its the only thing i can think of.... the tach has to be wrong on high rpm's the motor is screaming on top end if i go WOT it will bounce on and off the rev limiter.... Is there a way i can check this bad boy out with something els ?

 

[steelespike]

Re: Ok got her on the water.

As I understand it there are timng lights that have a rev counter.There are tachs that work of a mark placed on the revolving parts. A Tinytach is about $47 and easy to install and will work on any 2 cylinder 2 stroke regardless of stator poles.They have a website.You might be able to borrow a shop tach or get a tech to take a ride. A 13" prop is in the ball park.Is the prop worn/damaged?
I couldn't find a 96 48 SPL only a 95.Are you sure it has a rev limiter?
As I understand it the 48spl is a basic motor using premix and a manual trim.
Seems it wouldn't have a rev limiter.
The antivent plate sounds ok.I don't think more height would help at this point
anyway. the blistering hole shot leads me to believe it does need more pitch
but I wouldn't make the investment until you varify the tach.

 

[Rollinunknown]

Re: Ok got her on the water.

WoW!


Ok so i couldint get a gps today but just to let you know i have 6 people me 300lbs my unk 200 160lb girl 140lb girl 180lb guy and 170lb girl

1150 lbs + a 60+quart cooler full of everything .... 2 anchors 2 battery and 17gal's of gas and she still jumped up on plane with in 3-sec's wot 4000 RPM's crusiein along .

I was passing my buddy's 16ft 50hp jet john boat with nothing in it but him self!

The only thing i can think of is the tach is wrong so i will order the tiny tach and take this one back to Bass pro .


We drove all day and didint even burn 12 gals lol. we went down to the cove 19.8 miles down and back i maybe used 9gals TOPS!

 

[steelespike]

Re: Ok got her on the water.

Sure sounds like it is propped for a load. Performance borders on spectacular.
Just be careful of over reving till you get a Tach to check things.
Read up on the Tinytach it is an induction type and requires a prepared wire that can't be spliced. May be able to be too long but you may have to be careful how you handle the extra.

 

[Rollinunknown]

Re: Ok got her on the water.

*********** UP DATE got it fixed i put a 17p OMC alum prop and she FLYS now ... i dont know mph but its 2x the speed it was for sure!.

And the motor doseint strain a bit and just hums along @ 5250 rpms.
And i can stil have tons of gear with 3 grown adults over 200lbs each plus 8 poles 2 huge coolers ect.

Thanks a ton for your guys help.