Martin 20 won't run

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jimbrizzolara
Posts: 4
Joined: Sat May 19, 2018 10:41 pm

Martin 20 won't run

Postby jimbrizzolara » Wed Aug 08, 2018 3:05 pm

I picked up a 1949 Martin 20 at Tomahawk and went through it prior to testing in a tank. The motor has good spark, 94 lbs. compression, and a clean fuel system. It won't even "pop" when I try to start it. I removed the float bowl drain plug and gas poured out of it, so the carb is getting gas. The float and inlet valve are functioning properly. What bothers me is that gas-oil mix sprayed directly into the carb throat still does nothing. I removed the poppet valve and it looks perfect, as does the valve seat. Is there something I'm missing that's peculiar to the poppet valve system? Also, how are these motors synchronized? There's a rod and a spring with two adjustable stops on the left side of the engine block. This isn't my first Martin, but this one has me stumped.

XR55
Posts: 225
Joined: Mon Mar 09, 2015 3:44 pm

Re: Martin 20 won't run

Postby XR55 » Wed Aug 08, 2018 4:53 pm

What spark plug and gap are you using?

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Tom Manley
Posts: 343
Joined: Tue Mar 10, 2015 1:10 pm
Location: MA

Re: Martin 20 won't run

Postby Tom Manley » Wed Aug 08, 2018 5:44 pm

The WICO condensers are notorious for doing this. Difficult, but not impossible to find a replacement.

Tom

Jerry Ahrens
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Joined: Tue Mar 10, 2015 9:49 pm
Location: Lake of the Ozarks Mo.

Re: Martin 20 won't run

Postby Jerry Ahrens » Wed Aug 08, 2018 6:05 pm

I've ran into a lot of Wico condensors that were weak. Does that engine have O-rings on the valve skirts? I have a Martin 45 that had those O-rings, that were hard and dried out. They would leak crankcase pressure very badly when cranking the motor. I got replacements from Russ Larson, and that fixed the problem. That motor wouldn't even make a ''pop'' when trying to start it. Just an idea for you to consider...
Jerry Ahrens AOMCI Member MAPS Chapter President

jimbrizzolara
Posts: 4
Joined: Sat May 19, 2018 10:41 pm

Re: Martin 20 won't run

Postby jimbrizzolara » Wed Aug 08, 2018 6:34 pm

I'm using a J6-C plug with a .030 gap. It looked to me that there was not an O-ring on the valve, just a metal skirt, and the skirt and valve seat both look great. Does that mean that some Martins didn't use O-rings on the valves? As far as the condensers, I've been checking the spark by putting the plug in the boot and connecting a ground wire to the plug and the motor. I thought that I should check spark with a checker I have that shows the spark while under compression, simulating cylinder compression. I'm thinking you guys are on the right track about checking the condenser. I need to order an impeller from Russ anyway. Maybe I can temporarily use an OMC condenser to try things out. Thank you for the help, and I will let you know how it turns out. I was planning on entering this motor in an upcoming "how slow can you go" contest.

mercuryman
Posts: 436
Joined: Wed Mar 11, 2015 10:17 pm
Location: N. Florida

Re: Martin 20 won't run

Postby mercuryman » Wed Aug 08, 2018 8:42 pm

Gap plugs to .010 and see what happens.
Mercury -MK20, MK10, KH7, KG7,KG4, KE4,KE4, KE7, KF5,KF3,KE3,KD4
Wizard WH7, WD4
Johnson - QD15, HD26, TD20, KA38
Sea King 5, K1 (merc)
Evinrude- Foldlite 1930, ELTO - LW #309, 1951- 7.5, Zephyr, 68 3 hp
Bendix SMD , Champion 4.2 , Scott 7.5,

jimbrizzolara
Posts: 4
Joined: Sat May 19, 2018 10:41 pm

Re: Martin 20 won't run

Postby jimbrizzolara » Wed Aug 08, 2018 8:57 pm

If I gapped the plug to .010 and the motor fired, what would that mean?

mercuryman
Posts: 436
Joined: Wed Mar 11, 2015 10:17 pm
Location: N. Florida

Re: Martin 20 won't run

Postby mercuryman » Wed Aug 08, 2018 9:48 pm

Weak spark. Have you cleaned the points and checked for 1 ohm or less resistance across the points. Do you have the Outboarder Club Magazine it has a story on troubleshooting ignition systems. A good spark will jump a 3/16 " gap or more in free air, a weak spark will jump .030 " gap in free air but won't fire under pressure.
Mercury -MK20, MK10, KH7, KG7,KG4, KE4,KE4, KE7, KF5,KF3,KE3,KD4
Wizard WH7, WD4
Johnson - QD15, HD26, TD20, KA38
Sea King 5, K1 (merc)
Evinrude- Foldlite 1930, ELTO - LW #309, 1951- 7.5, Zephyr, 68 3 hp
Bendix SMD , Champion 4.2 , Scott 7.5,

mercuryman
Posts: 436
Joined: Wed Mar 11, 2015 10:17 pm
Location: N. Florida

Re: Martin 20 won't run

Postby mercuryman » Sat Aug 11, 2018 4:19 pm

I have a Martin 40 that ran bad and hard to start. I got it out after your post and today it won't start and has real good spark. I removed the valves and pulled off a O ring it was hard. When to my O ring box and found a fit. Put it back together and now it runs super good. So O rings can look good but will leak when hard.
Mercury -MK20, MK10, KH7, KG7,KG4, KE4,KE4, KE7, KF5,KF3,KE3,KD4
Wizard WH7, WD4
Johnson - QD15, HD26, TD20, KA38
Sea King 5, K1 (merc)
Evinrude- Foldlite 1930, ELTO - LW #309, 1951- 7.5, Zephyr, 68 3 hp
Bendix SMD , Champion 4.2 , Scott 7.5,

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Tubs
Posts: 1925
Joined: Thu Mar 12, 2015 7:47 am

Re: Martin 20 won't run

Postby Tubs » Sun Aug 12, 2018 9:39 am

Yep. The valves need to have good (flexible) O rings.
O Rings.jpg
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