Where is my mid range power

[npenson]

I have a 81 70hp evinrude, It sat for many years before we bought it. The problem i am having is it will not take any throttle, what i mean by that is anything over 1500rpm it cuts out, unless you tap the choke and push the throttle at the same time once over 4k it runs fine back off and it does it again.

all maintance has been rebuilt carbs, (complete diss and clean) rebuilt fuel pump with 2.5psi at first couple cranks and 4.5 at about ten, new plugs gaped at .040 showing fire at all cyl., comp. was 125 125 118, all new fuel lines from motor to tank.

just not sure where to go now have tried all new jets and everything i know its got to be a fuel problem because it will take off every time when you pop the choke

thanks any help would be so very welcome i am pulling my hair out now

nick

 

[tashasdaddy]

Re: Where is my mid range power

did you do all of this http://forums.iboats.com/showthread.php?t=244013, sound like you have clogged high speed jets. you do not have a mid speed jet. also have you done a link and sinc on the motor, coordinating the spark and carbs.

 

[npenson]

Re: Where is my mid range power

yeah done the link sync, and it has new low and high speed jets in it, i kept thinking it was that too but took them apart again today and no clogs

 

[npenson]

Re: Where is my mid range power

anyone else have any ideas what this could be, reeds or powerpack or the timing base wouldnt do this would it?

 

[tashasdaddy]

Re: Where is my mid range power

tapping the choke makes it pickup, means it is fuel related. vent open on fuel tank?

 

[HighTrim]

Re: Where is my mid range power

It does sound like the jets, but check to see if the timer base (starboard side, under the edge of the flywheel, linked to the throttle lever) moves smoothly without sticking when you advance the throttle.

Take the airbox cover off & observe whether the throttle plates are parallel.

Also, the timer base should start it's travel *before* the throttle plates start to open, else she'll fall flat when you try to accelerate.

 

[kynolan2183]

Re: Where is my mid range power

I have the same motor and it did the same thing.
You need to set the timing in the water only using the timing to increase the rpm. Then set the throttle pickup.

I can set mine on muffs in the driveway but it is tricky.
I have to set the timing at 6 degrees after TDC when in the driveway on muffs. Then set the trottle pickup. Next drive 15 miles to the lake and adjust a little more. At 6 degrees for idle in the driveway it will shake your fillings out. But once in the water with back pressure it is fine.

Also make sure that the ball and socket connection to the timing advance has absolutly no play in it or you are waisting your time.

From what I have found on my motor that is.(1984 70 hp)

Do a search in the net for photos of your motor smalloutboards.com had some a while back. Look at the location of the time cam and screw adjustment. More than likely yours is not set right. The timing screw should have about 1/4 inch or less of adjustment left to the head of the screw.
Good Luck

Kyle

 

[npenson]

Re: Where is my mid range power

thanks everyone for the help, yes the vent is open, and i will try seting the timing in the water i did have the same problem the first time we put it in the water (with the timing that is) but had seamed to be fine. I took the carbs off again today and are dipping them and rebuilding them myself (didnt last time) so my kits will be here friday. so I will let you know what happens.(btw i did find a little sluge under the plug thats in the float chamber so i dont think they got pulled on the first rebuild but nothing in the jets from what i could see)

thanks
nick