1976 evinrude 25 power issues

[Ampegor]

I recently purchased this engine for cheap knowing it would need some work

when I got it it was only running on one cylinder

I pulled the fly wheel and found the points worn down bad
I replaced points set at 20 thou slight drag on the set mark of cam

reassembled and the engine started right up

the unit gas good compression about 125 psi both cylinders and I have cleaned the carb

the issue I am having us the engine seems slow to wind up and I don't think it's making full power.

Also it is hard to set the low idle as it tends to die easy at idle speeds I have adjusted the low speed mix and it helped some but still not that good

I think that maybe the timing is off causing this

as stated above I set new points at 20 thou at set mark on cam

is there some other way to check timing on this engine that does not require a timing light as I am at camp for two weeks
I do have a multimeter

any help is appreciated

Andy

 

[F_R]

As you must be aware, the magneto plate rotates as you operate the throttle. As such, that means you are changing the timing with each change in throttle position. So you do not have a timing problem.

There is another timing function, that is timing when the points open in relation to when the magnets pass by the driver coil. That is controlled by the points gap. There is a timing fixture for adjusting the points gap precisely, or you can just do it by setting them a 0.020", which you have done. That is good enough.

So what now? Slow to wind up might be due to too much prop pitch. You can experiment with different props, or you can just live with it. Even the best and most expensive prop can do little if the horsepower is insufficient for the boat and load.

Lastly, you might as well know that that motor never was the best at running at idle speed. Blame that on the early attempts at controlling emissions into the water. Again, adjust it the best you can and accept it.

I know this is not what you wanted to hear.

 

[oldboat1]

The cam follower and roller on the intake manifold has to contact the throttle control cam on the timing plate at the precise moment the carb throttle valve begins to open (the link and sync). That is a timing issue you can address.

The roller has to first touch the plate at the scribed mark on the plate (between the two marks on yours, I believe) to synchronize timing and throttle. Look for the roller and the assembly — adjustment on yours may involve moving the plate slightly to adjust. When the roller is at the high point of the plate, the throttle plate should be fully open. It may be that yours is not fully open at WOT.

It’s easier to do than to describe. Check the operation on yours.

 

[Ampegor]

I am not expecting it to idle or troll like my 9.9 but it will not hold an idle speed at all
it will idle down to about 1000-1200 rpm by ear but not stay running any lower
the manual I have says around 700 rpm idle

as for power it's the stock prop and the boat is an 80s vintage crest liner deep and wide 14 ft tinner and I only get about 18 mph on gps
i would figure 22-23 more reasonable
my friend with a 20 hp is faster in a similar size and weight boat

 

[Starboardlean]

Just throwing this out there..I caught heck with mine idling. Your magneto plate ain't wobbling is it. I had to ping mine. I guess that wobble alters timing.

 

[Ampegor]

I think it's a timing issue and that makes sense
was going to pull the flywheel and check the points again will check it while I am in there

 

[racerone]

Picked one of these motors up for parts sometime ago.-----Bottom crankshaft seal was installed totally wrong.-----Have you checked reed valves ?

 

[Ampegor]

Update

thanks to suggestions above it is now running great
I took the flywheel off and examined the stator assembly and found it loose and wobbly
I tried the ping method and with a few taps got the plate nice and tight and wobble free

the engine now idles nicely around 700-750 rpm
thanks all

 

[Starboardlean]

Wow, my first "assist"..