Calling All Setup Gurus :)

[zibzer]

Hello,

heres the deal, I have a 1979 Evinrude 100hp 13 3/4*15 prop

boat runs 5000rpm at wot on a 17.5ft Peterborough Runabout.

it gets 27mph. Id like to gain 600-800rpms. But am unsure of how!... plus... i would guess that the motor/prop combo would push this boat to 5800rpm easily, but apparently it doesn't.

Any help would be much appreciated

 

[zibzer]

Re: Calling All Setup Gurus

few more things i should mention

the motor starts easily and purrs like a kitten at idle.

accelerates like a bat out of hell but falls flat at 4800rpms.. when i adjust the trim I get another 200rpms out of it. on a really calm day I may be able to push another 100-200rpms out of it.

I also payed a professional to "setup" the mptpr/boat as i bought the motor seperate last spring.

And i noticed the primerball doesnt hold pressure for more than 10-15minutes before i would have to firm it up... could this be causing a problem? i bought a new bulb and gas line but that one i cant get it to suck any fuel erven after 5 minutes of priming.

 

[wavrider]

Re: Calling All Setup Gurus

Zibser,

you will probaly get a better response in the prop section, there are numerous members who have vast knowledge of set ups and obtaining the best possible performance out of engine, prop and set up there

lower your engine down as if you would be using it in the water. take a picture of your lu and prop anti cavitation plate with your transom in the background, this will give the members the visual info they need to give you advice, good luck I am sure thay will respond with any info once you have it in the right forum and with the correct picture for reference

 

[tashasdaddy]

Re: Calling All Setup Gurus

that is a heavy boat, but i would expect a little more out of it. like mid to high 30's with a well 100 rude. I use to run a 90 on that size and weight. is your AV plate 1- 1 1/2 inches above the Keel ( straight edge alone keel out beside the foot, should be parallel with the straight edge, and higher. also getting the prop correct, these both will help you boat,

moving to prop forum.

 

[zibzer]

Re: Calling All Setup Gurus

that is a heavy boat, but i would expect a little more out of it. like mid to high 30's with a well 100 rude. I use to run a 90 on that size and weight. is your AV plate 1- 1 1/2 inches above the Keel ( straight edge alone keel out beside the foot, should be parallel with the straight edge, and higher. also getting the prop correct, these both will help you boat,

moving to prop forum.

im going to run down to the lot where my boat is parked and snap some pictures of the motor setup. ill be back in 45 minutes!

 

[Dhadley]

Re: Calling All Setup Gurus

OK, you're on the clock................

 

[zibzer]

Re: Calling All Setup Gurus

heres some pictures of the transom.. i couldnt lower the motor all the way because the motor would be touch the ground.

 

[zibzer]

Re: Calling All Setup Gurus

another thing.. the plate on the back says MAX POWER = 63Kw

I looked on the net and this calculates to 84.5hp? Can that be right?

 

[72SideWinderSS]

Re: Calling All Setup Gurus

I would raise the motor up 2 holes and try it again.
Also I would remove the whale tail.
jmho

 

[Silvertip]

Re: Calling All Setup Gurus

The primer bulb will not stay firm once the engine is running. Why???? Because fuel is being sucked through it, not forced through it.

 

[Theoutdoorsman]

Re: Calling All Setup Gurus

Your in excellent hands now zibzer!!!!! I'll be looking for smiles when your finished........... ......... Good luck sir.

 

[zibzer]

Re: Calling All Setup Gurus

The primer bulb will not stay firm once the engine is running. Why???? Because fuel is being sucked through it, not forced through it.

i mean, it wont stay firm sitting in the driveway.. not running.

i plug the quick connect to the motor.. pump about 10-15 times to get hard, sit down in the lawn chair and have a beer or 2, then when i come back I need to pump another 3 times to firm it up.

 

[zibzer]

Re: Calling All Setup Gurus

how many rpms do you think ill gain by bringing the motor up 2 holes? .. plus, is there an easy way to do this? I see there is a spot to hook a pulley up to, but im living in the city and there is no access to a tree or anything to wrap a rope around.

 

[zibzer]

Re: Calling All Setup Gurus

doing some searching on the forum I might gain 200rpms by bringing it up 2 holes.

if i do this i will be at 5200RPMs

to gain another 600rpms to not lug the motor.

to gain 600 rpms i need to drop to a 12Pitch Prop

in this case i wouldnt be chaning my max speed at all but i would have a higher reving engine.

anybody else have some opinions? could I have a motor fuel delivery problem at high speeds?

 

[72SideWinderSS]

Re: Calling All Setup Gurus

What is your compression readings ?
When was the last time you de-carbonized the motor?
When was the last time you cleaned and rebuilt carbs and did a link and sync?
Are your throttles opening all the way (horizontial)?
Is your max advance within spec. ?

Just some things that should be confirmed to rule out possibilities.

 

[zibzer]

Re: Calling All Setup Gurus

When was the last time you de-carbonized the motor?
When was the last time you cleaned and rebuilt carbs and did a link and sync?
Are your throttles opening all the way (horizontial)?
Is your max advance within spec. ?

havent really checked all that. I suppose its time. Although if some of these were out of adjustment I would think there would be other problems. Thanks for the tips. time for me to get busy.