1952-54 Johnson Seahorse 3HP (JW-10): Carb problems and other issues

[itstippy]

Re: 1952-54 Johnson Seahorse 3HP (JW-10): Carb problems and other issues

What did the compression numbers look like? If it has good compression it will run. If compression is poor it will not run.

 

[tmcalavy]

Re: 1952-54 Johnson Seahorse 3HP (JW-10): Carb problems and other issues

Like itstippy said, time to check compression at the plug holes for cylinder compression and then where the carb bolts up for crankcase compression....just to verify that this is indeed a carb problem. A compression tester will tell the tale on cylinder compression. To check carb compression, remove the carb and place a light piece of paper over the opening for the carb...If it has crankcase compression you'll see the paper move in and out as the pistons/flywheel move. If compression checks out both places, may be time to place an ad in the free Webvertize ads at http://www.aomci.org for a carb. Shouldn't cost too much. Might check the links page at that site, too. There may be a spring swap meet coming up in your area soon...good place to prowl for parts. Don't give up on it until you check the compression.

 

[tmcalavy]

Re: 1952-54 Johnson Seahorse 3HP (JW-10): Carb problems and other issues

Oops..meant to say "To check crankcase compression..." in the above post.

 

[aborgman]

Re: 1952-54 Johnson Seahorse 3HP (JW-10): Carb problems and other issues

Like itstippy said, time to check compression at the plug holes for cylinder compression and then where the carb bolts up for crankcase compression....just to verify that this is indeed a carb problem. A compression tester will tell the tale on cylinder compression. To check carb compression, remove the carb and place a light piece of paper over the opening for the carb...If it has crankcase compression you'll see the paper move in and out as the pistons/flywheel move. If compression checks out both places, may be time to place an ad in the free Webvertize ads at http://www.aomci.org for a carb. Shouldn't cost too much. Might check the links page at that site, too. There may be a spring swap meet coming up in your area soon...good place to prowl for parts. Don't give up on it until you check the compression.

Cylinder compression looks a little low, but not that bad - about 80-82psi.

Crankcase compression, I can't tell. It sort of looked like it flapped the paper a little, but it certainly is super subtle if that is the case. Any other suggestions for checking the crankcase compression?

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aborgman

 

[aborgman]

Re: 1952-54 Johnson Seahorse 3HP (JW-10): Carb problems and other issues

Crankcase compression, I can't tell. It sort of looked like it flapped the paper a little, but it certainly is super subtle if that is the case. Any other suggestions for checking the crankcase compression?

Checked this again this morning with a pieve of really fine tissue paper, and it does look like it is moving it.

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aborgman

 

[itstippy]

Re: 1952-54 Johnson Seahorse 3HP (JW-10): Carb problems and other issues

Those cylinder compression numbers are great. The JW's I've messed with either had good cylinder compression (70 and up) and ran well. Really well. Sweetheart motors. Or they had poor cylinder compression (below 60) and were hard starting poor runners.
I've never tested crankcase vacuum. The crankcase test makes sense, though. A bad seal in the case or a bad reed would let air in/out through an alternative route rather than IN through the carb intake and OUT through the exhaust ports. To get an accurate appraisal of crankcase vacuum you'd have to do the test described with the sparkplugs in. Otherwise the "suck" part of the piston's up/down would just draw air in through the open sparkplug hole.
After you've pulled your arm off trying to start this thing, are the plugs all soaked with gas?

 

[tmcalavy]

Re: 1952-54 Johnson Seahorse 3HP (JW-10): Carb problems and other issues

If it moved the paper with the plugs out, moving it in and out, it has crankcase compression...especially with the plugs in and some fuelil in the cylinder. May be time to troll for a new-old replacment carb. Try the free Webvertize ads at http://www.aomci.org and maybe ask on the Ask a Member board there if another carb will interchange.

 

[aborgman]

Re: 1952-54 Johnson Seahorse 3HP (JW-10): Carb problems and other issues

If it moved the paper with the plugs out, moving it in and out, it has crankcase compression...especially with the plugs in and some fuelil in the cylinder.

I didn't try it with the plugs out - with the plugs in I get a slight movement of some tissue paper, but it is pretty slight.

IMay be time to troll for a new-old replacment carb. Try the free Webvertize ads at http://www.aomci.org and maybe ask on the Ask a Member board there if another carb will interchange.

That might end up being an option, depending on cost... considering I have a line on a running 4hp 1976 Chrysler for $80 - I may just give up and sell this thing though.

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aborgman

 

[aborgman]

Re: 1952-54 Johnson Seahorse 3HP (JW-10): Carb problems and other issues

Those cylinder compression numbers are great. The JW's I've messed with either had good cylinder compression (70 and up) and ran well. Really well. Sweetheart motors. Or they had poor cylinder compression (below 60) and were hard starting poor runners.
I've never tested crankcase vacuum. The crankcase test makes sense, though. A bad seal in the case or a bad reed would let air in/out through an alternative route rather than IN through the carb intake and OUT through the exhaust ports. To get an accurate appraisal of crankcase vacuum you'd have to do the test described with the sparkplugs in. Otherwise the "suck" part of the piston's up/down would just draw air in through the open sparkplug hole.

I did it with the plugs in... but I'm still not sure it's sucking very good. Wish I had a vacuum gauge and some idea just how much vacuum it was supposed to pull. As an engineer I tend to prefer real actual measurements...

After you've pulled your arm off trying to start this thing, are the plugs all soaked with gas?

A good question, and honestly I don't remember. I'll haul it back outside in the snow this afternoon and yank on it for a while (with the plug wires disconnected) and see if the plugs are getting wet... I'm going to pull the flywheel and check the timing again also - always possible it slipped a bit.

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aborgman

 

[aborgman]

Re: 1952-54 Johnson Seahorse 3HP (JW-10): Carb problems and other issues

After you've pulled your arm off trying to start this thing, are the plugs all soaked with gas?

So I took it out in the snow, put the tank back on, and spun it over about 30 times... and the plugs are dry. So it appears she ain't sucking. The question now is why not?

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aborgman

 

[lark2004]

Re: 1952-54 Johnson Seahorse 3HP (JW-10): Carb problems and other issues

I'd be checking your reeds. If they are broken, then the crankcase won't pressurize to force the fuel/air mix up into the cylinder.

 

[itstippy]

Re: 1952-54 Johnson Seahorse 3HP (JW-10): Carb problems and other issues

You don't have a whole lot to lose so try this for fun. Spray some PB Blaster or other good penetrant into the plug holes to hopefully help loosen any stuck rings. Give her a few pulls to blow out the excess penetrant. Put the plugs back in. Take the manual starter assembly off. Get a 1/2" chuck variable speed drill. Find a socket that fits the flywheel nut. Take an el cheapo 3" socket extender and cut the female end off with a hacksaw. Use it as a mandrel for the socket to fit it into the drill. Mount the motor securely over your water barrel, get good footing balance, and start that %$@##& thing.

 

[aborgman]

Re: 1952-54 Johnson Seahorse 3HP (JW-10): Carb problems and other issues

I'd be checking your reeds. If they are broken, then the crankcase won't pressurize to force the fuel/air mix up into the cylinder.

The reeds look good.

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aborgman

 

[aborgman]

Re: 1952-54 Johnson Seahorse 3HP (JW-10): Carb problems and other issues

You don't have a whole lot to lose so try this for fun. Spray some PB Blaster or other good penetrant into the plug holes to hopefully help loosen any stuck rings. Give her a few pulls to blow out the excess penetrant. Put the plugs back in. Take the manual starter assembly off. Get a 1/2" chuck variable speed drill. Find a socket that fits the flywheel nut. Take an el cheapo 3" socket extender and cut the female end off with a hacksaw. Use it as a mandrel for the socket to fit it into the drill. Mount the motor securely over your water barrel, get good footing balance, and start that %$@##& thing.

Well, that will almost certainly get it started

...but I've gotten it started several times, and it hasn't made it behave any better - you think it would loosen a ring that hadn't already been loosened by th previous running?

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aborgman