Old 15hp fleetwind knocks

[ba_50]

Evinrude superfast twin 15hp 15012-47097

This motor is new to me. I cleaned the carburetor and went from 30 sae to 24:1 two cycle oil. It is hard to start and it ran about 1 minute after putting the carb back on. It was knocking until the low speed needle was leaned out. After 10 seconds it started knocking again. I took the top side plate off the top piston and cylinder and there is no sign of burning or damage.

It was in neutral so I don't believe the gearcase has anything to do with it.

What can I check? Thanks.

 

[outlaw241]

Re: Old 15hp fleetwind knocks

maybe pull the recoil starter off an start it with a rope to eliminate the recoil, i have seen starter paws cracked an made a ticking noise

 

[ba_50]

Re: Old 15hp fleetwind knocks

maybe pull the recoil starter off an start it with a rope to eliminate the recoil, i have seen starter paws cracked an made a ticking noise

I don't think it is the starter.

It will keep running if I set the mixtures just right. Either too lean or rich and it starts bucking. It is in a bucket of water so I can't adjust the hi speed yet.

 

[nwcove]

Re: Old 15hp fleetwind knocks

is it "knocking" or just running rough? big diff between knocking and bucking!

 

[jbjennings]

Re: Old 15hp fleetwind knocks

You should get a spark tester and check for spark on both cylinders. Those motors often have bad coils.
If you're really hearing a knock, take the plugs out, and turn the flywheel until the piston is almost at top dead center. Reach in gently and push in on the piston with a screwdriver to see if there's any slop in the wristpin. If there's any slack, you'll feel it. If you have a knock, that's the most likely cause of it, is bad wrist pin bushings. I still suspect it's only running on one cylinder due to lack of spark on top or bottom. If you haven't done a compression test, that would be a good indicator of the motor's condition. Usually between the wrist pin slop test and a compression test, you can tell if a motor is worth working on.
GOod luck,
JBJ

 

[ba_50]

Re: Old 15hp fleetwind knocks

You should get a spark tester and check for spark on both cylinders. Those motors often have bad coils.
If you're really hearing a knock, take the plugs out, and turn the flywheel until the piston is almost at top dead center. Reach in gently and push in on the piston with a screwdriver to see if there's any slop in the wristpin. If there's any slack, you'll feel it. If you have a knock, that's the most likely cause of it, is bad wrist pin bushings. I still suspect it's only running on one cylinder due to lack of spark on top or bottom. If you haven't done a compression test, that would be a good indicator of the motor's condition. Usually between the wrist pin slop test and a compression test, you can tell if a motor is worth working on.
GOod luck,
JBJ

The pistons didn't have any play and both cylinders were firing. I noticed it helped if I hit the primer on the tank and realized the gas cap wasn't on tight. After tightening the cap and adjusting the needles it ran ok for 10 minutes in a tub of water.

It will have to go to the river before I can put it in gear and tune it further.