1969 evinrude 25hp issue

[Sascwatch]

first off, I want to say this forum is awesome. I've been tinkering with 1960-1970 era evinrudes/Johnson motors for a few years when I had 2 9.5 sportwins given to me and they run awesome now. Everything k needed was on this forum.


So now to the problem im having. I picked up a 1969 evinrude 25HP the other day in hopes of getting a bit more power on my 14 foot tinny. The seller said he had replaced the shifting fork (clutch dog??). Nothing else had been done.

I replaced the points and condensers, coils look good and I get a nice spark. I put in some C6J plugs and the motor fired right up in the barrel, ran good and revved up nicely. The thermostat was sticking aswell so I replaced that too.

I took the motor out today for its maiden voyage and once again it fired right up, went nice and fast just like I wanted and then BOOM it felt like I hit a rock or log, slowed the boat down and check it out, nothing wrong at all. So here I go again and it happens several times, maybe once every 200 yards.

I've read online a bit and I'm thinking it's either a "lean hiccup" or it's popping out of gear, the engine doesn't rev up at all when this happens and it continues to fly along no problems except this one issue.

I took a short video of the motor running in a barrel, this is with new fuel 50:1. To me the plugs look dry as they are a light brown color in both cylinders. .020 gap on the points and .030 on the plugs.

http://youtu.be/EWC4-_IMoms

The video isn't very good, but the motor is in gear and I'm giving it a bit of throttle. In the video it sounds like it clicks but it's more of a cough. When I'm on the river at a higher speed it's worse. The whole motor will shake as if it hit a log and return to normal. There's no feedback in the shifting lever either.

Anyways I'm looking for opinions before I dig into this deeper. If anyone needs more info just let me know. I may go out and take a better video tomorrow on the water.

 

[ultra353]

You have a lean idle condition , try turning out the low speed mixture control counterclockwise 1/8 turn at a time then let motor respond to the changes for a minute , keep doing this proceedure till it runs smooth. If it doesn't clean your carb

 

[ultra353]

On the clutch dog issue , sounds like the previous owner didn't change the the fwd gear which was wore out like the old clutch.

 

[Sascwatch]

Here what I've done so far to the motor since I got it:

-new points and condensers.
-changed the impeller.
-changed the bottom end fluid.
-replaced the fuel line from the connector to the pump.
-removed the carb, disassembled what I could and blew it out with compressed air.
-new J6C spark plugs
-cleaned the screen in the fuel pump
-low speed mixture set to 1.5 turns from seated

I plan on changing the fuel line from the pump to the carb and installing a carb kit. Just have to find a part number for that. I will tear open the bottom end aswell as I've got a bit of water in my oil, new seals are on the way.

Ill start with the idle mixture tomorrow after I change the line from pump to carb.

 

[hardwater fisherman]

Carb kit with float sold here at IBOATS part number 18-7222.

 

[Sascwatch]

Cool thanks, is 18-7823 the correct part number for a fuel pump kit?

 

[hardwater fisherman]

If you have the small square fuel pump it should be the right kit.

 

[60sboater]

I bought a '72 25hp Johnson last month and it was doing the same thing. I replaced the J8Js with J4Js and ran some new Shell 89 at 50:1 and it ran smoothly in the barrel. Last week it did it after starting and I choked it some for a few seconds and it smoothed-out and then opened the choke all the way. I have not had it on the river yet but will soon.

 

[Sascwatch]

I haven't looked at the clutch dog/gears yet or even checked the shift linkage, but I've been looking at prices for those parts. Man they sure aren't cheap!

Anyways I've found what I think are some good parts motors with one looking almost new.

http://www.kijiji.ca/v-powerboat-mo...or/1085041939?enableSearchNavigationFlag=true

http://www.kijiji.ca/v-other-boat-w...76/1080219049?enableSearchNavigationFlag=true

Motor starts up and idles nicely now with a bit of adjusting to the low speed mixture screw.

Once I open up the lower unit and see what's going on I'll update this thread. I'm hoping it's just a shift linkage problem as the previous owner says he had removed the lower unit before.

 

[Sascwatch]

Ended up putting a carb kit, fuel pump kit, water pump kit and bottom end seal kit in. Clutch dogs show minor signs of wear on the forward side with reverse looking good.

It looked as if the shifting fork had hit the outer casing of the skeg before as there were some scratches inside.

I'm thinking the shift linkage wasn't adjusted correctly. Hope it's fixed now. Will do a test on the boat to find out.

 

[Sascwatch]

Tested it out, no more clunking in forward or reverse. Checked oil after and no water in it either.

New issue tho, at WOT it seems to have no power once it gets going unless I put the choke on. Will have to reclean the carb and check my fuel pump rebuild job.

 

[Sascwatch]

Finally had time to look into my WOT issue, fuel pump is spraying fuel nicely so I guess I've got to tear into the carb again. Must have clogged up something.

i also notice the top crankshaft seal under the timing plate is leaking a bit so that'll have to be replaced aswell.

on a side note, the motor started up in 1 pull after sitting for a few weeks. Will probably be a while before I fix it because of a bear hunting trip in a few days.