Before I get too drastic...

[tunaticer]

My '96 rude 25 2 stroke played up today.
Full throttle with no miss gives about 1/3rd power.
Idles and starts as per normal.
Fuel is 2 months old, but this old donk will happily digest anything.
Pump the bulb makes no difference.
Vents in the tank are good.

1st of all I intend to replace the fuel pump kit, it is still original.
2nd I will replace the primer bulb and O rings in the fuel connectors, they are about 5 yrs old and probably sucking air.
3rd I will run a decarb through it, never had one before.
4th will see me replace the surface gap plugs......they would be 18 yrs old now.
5th will hopefully see it run fine again.
If that doesn't change anything I will overhaul the carbs with new kits.

If it doesn't change anything, how would I go about testing the powerpack or coils?

What am I missing that I should also attend to prior to electrics?
Is there any way the timing may not be advancing on these old motors?

[Lucky_Phill]

Don't know if this is much help, but sounded similar to my old 40 Yammie.

It was a loose screw that holds a lever on the carbs... no advance thingie.

Not a mechanic so don't know names of things. But this little lever thing is quite visible.

cheers

[Gon Fishun]

Butterfly opening fully via throttle control?

[tunaticer]

Thanks guys, Will pull the cowl off tomorrow and check the linkages and butterfly for operation first.

[Funchy]

Its done 50,000 hrs mate, let it retire and get an etec? ;p

[solemandownunder]

We had the same problem when we 1st bought our 60 Jonno 1984 model.
The motor ran fine, but only produced around 6 knots speed....obviously we turned around and came home.

It was the CD2 unit failing under load....new one in....no more probs.
We were told by our mechanic that these cannot be checked accurately and the problem only shows up out on the water, under load.

Maybe you could look at that after checking everything else.

Cheers, R & K.

[tunaticer]

I think it passed the 50 000 hours a few years ago Luke.....as for the Etec possibly in december on a new tub

[Spaniard_King]

Hold the bus

Do or get a compression test before you WAISTE any money on it

[fat-buoy]

My old Yammie did the same thing a while back.. turned out that the nylon end of a linkage had snapped and was not pushing the butterfly open... cost something like $10 to fix

[Noelm]

Yep, Spaniard KIng is on the money, do NOT try a scattergun approach, so far you say, pumping the fuel bulb does not help, that eliminates the fuel pump and the associated fuel line etc, do NOT do a decarb, first things first, compression test, very low cost, non invasive and CAN tell you a lot, from your post you are going to try to fix everything from fuel to electrics with no idea at all if any of them at at fault, have a real good look to make sure the choke if turning fully off, the throttle is opening full and so on, simple stuff.

[tunaticer]

Did a cold dry compression test this arvo 120psi top pot 118psi bottom pot. (pull rope testing)
Searched around and checked the butterfly operation was only getting about 1/3rd open.....traced back the linkages and found a grub screw in a cable clamp wasnt tight and about 6mm of excess play. Removed that play and checked the throat and get a full open throat now.
Fired it up on muffs and it ran just like it always did on muffs no misses or farts.....water test it again this weekend to see if that was 100% of the problem.
Plugs were slightly carburised but not as much as I expected after being in there so long, a quick clean up and back in they went. Fired first pull with the normal choking sequence.
The choke is a 5ml charge of fuel by plunger, not a butterfly choke.

[wayno60]

Job done!!

[tunaticer]

Now that is sorted, what is the concensus on giving the donk a decarb now??

Do or don't?

I am still going to rekit the fuel pump and new o rings to the fuel connectors and a primer bulb.