Merc 200 bucking?

[ShafferNY]

I got the old mercury out on the water today and it wouldn't run very good. It acted like it was only running at about half power, and at idle it would spit and sputter like it was miss-firing. It would buck as if it were trying to kick back, ya know when you start it sometimes. <br /><br />It sounds like the timing could be off. How do you check the timing on these motors? It says 38* BTDC. <br /><br />Oh, just in case you don't know by now, it's the '78 20hp I'm working on. <br /><br />To top everything off today, the starter crapped out. I took it a part and the brushes are shot. The wires are bad on them. <br /><br />Were can I find a new set of brushes at? I tried Aubuchons, and all the autoparts places but no-one could help me out. I figured someone has to have them. All they are is 1/4" square by about 3/8" long. <br /><br />TIA

 

[Bob H.]

Re: Merc 200 bucking?

You're going to need manual. Once you get the starter fixed you'll probably need to pull and clean the carb(s).

 

[ShafferNY]

Re: Merc 200 bucking?

I ordered a manual, but it still hasn't showed up. <br /><br />This seems like an ignition problem to me, but it probably wouldn't hurt to clean the carb out anyway.<br /><br />I know this motor has been sitting awhile. There was a rat's nest between the cowl and powerhead when I first got the motor. I removed the nest and blew everything out with air to get into the places I couldn't reach. <br /><br />All the wiring looks good.

 

[ShafferNY]

Re: Merc 200 bucking?

I took the carburetor apart and it was as clean as a whistle. I was shocked. <br /><br />I put it back on and tried to start it. I did the samething as before. Thinking it was something to do with the timing, I took the flywheel off. The key was sheared. I'm not sure why it sheared off. It may just be due to a simple misfire.

 

[Nos4r2]

Re: Merc 200 bucking?

I've repaired starters with dead brushes before by cutting down washing machine brushes to the right size and re-soldering the leads. Works a treat and costs very little-but you've got to make sure they fit as well as the factory ones or they'll chew up the armature.

 

[ShafferNY]

Re: Merc 200 bucking?

I'm getting desperate, so I might just try that. I can't seem to find them anywhere. I can't even find another used stater that's the same. <br /><br />What did you use to cut them down? File, bench grinder?

 

[Nos4r2]

Re: Merc 200 bucking?

Hacksaw and a couple of files.The surface that touches the armature has to be nice and smooth.

 

[wilde1j]

Re: Merc 200 bucking?

Flywheel key problem is caused by the bore/crankshaft mating surface not clean and dry (never any oil) AND/OR not using a torque wrench when tightening the flywheel nut. You may have to lap the flywheel bore and crankshaft surface to get a proper seating.<br /><br />I would use fine sandpaper to clean up the commutator while spinning the armature.

 

[ehenry]

Re: Merc 200 bucking?

Go to an automotive electrical repair place. Somewhere that only repairs starters, alternators and generators and such. THey generally can get most any type brush you could possibly want.