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Pony Motor Compresssion

Pony Motor Compresssion

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lrolla
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I've been doing battle with the pony motor on a 1950 D2. I've rebuilt the mag, have the m on the flywheel lined up with the m on the mag. Good spark. Carb has been dipped and a fresh rebuild kit with new gaskets. Did not drill out the bb's. New plugs and wires. When I turn it over she doesn't start. Plugs are wet but not too wet. I'm still not ruling out the carb as the problem but wondering if 60psi for each cylinder is acceptable. I'm thinking that it's very low and could be the problem but need some advice from the experts.

Thanks,

Larry
Larry Rolla
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Sat, Nov 27, 2010 9:57 AM
Old Magnet
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Have you got the mag timed to the camshaft gear.
Remove the pipe plug from the back side of the mag and align the "M" stamped on the magneto gear and the camshaft gear.

60psi is good compression....they seem to function even as low as 40psi.

When you get it going if the carb responds to adjustments and you don't have to run with choke applied you accomplished that task.
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Sat, Nov 27, 2010 10:55 AM
zootownjeepguy
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Reply to Old Magnet:
Have you got the mag timed to the camshaft gear.
Remove the pipe plug from the back side of the mag and align the "M" stamped on the magneto gear and the camshaft gear.

60psi is good compression....they seem to function even as low as 40psi.

When you get it going if the carb responds to adjustments and you don't have to run with choke applied you accomplished that task.
I rebuilt a carburetor for my D2 pony and had the same problem. It's a little tricky adjusting the mixture screws because of the linkage for the main needle. You can't tell if it's seated, and you screw it IN to adjust the mixture rich, OUT to lean. It takes some time, but you'll get it eventually.👍
Rich Salvaggio
D2 5U9917
'46 Willys CJ2A Farm Jeep, '39 Buick sedan, '49 International KB-7, '37 Allis Chalmers WC, Cushman Scooter(s)
Antique garden tractors & outboard motors
Other rusty old junk comes & goes without warning.

The 2 most useful tools to have in your shop are a Crystal Ball and a Magic Wand
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Sat, Nov 27, 2010 11:02 AM
lrolla
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Reply to Old Magnet:
Have you got the mag timed to the camshaft gear.
Remove the pipe plug from the back side of the mag and align the "M" stamped on the magneto gear and the camshaft gear.

60psi is good compression....they seem to function even as low as 40psi.

When you get it going if the carb responds to adjustments and you don't have to run with choke applied you accomplished that task.
[quote="Old Magnet"]Have you got the mag timed to the camshaft gear.
Remove the pipe plug from the back side of the mag and align the "M" stamped on the magneto gear and the camshaft gear.

60psi is good compression....they seem to function even as low as 40psi.

When you get it going if the carb responds to adjustments and you don't have to run with choke applied you accomplished that task.[/quote]

OM, Yes I've got the two "M" stamped on the magneto gear and the camshaft gear perfectly aligned. I used a mirror and a flashlight to see the alignment. Almost wanted to take a picture so I could show my neighbors who are more knowledgeable than I. I'm 100% confident that is not the problem.

Good to know that the 60psi is ok. I'll keep playing with the carb.
Larry Rolla
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Sat, Nov 27, 2010 2:43 PM
lrolla
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Reply to zootownjeepguy:
I rebuilt a carburetor for my D2 pony and had the same problem. It's a little tricky adjusting the mixture screws because of the linkage for the main needle. You can't tell if it's seated, and you screw it IN to adjust the mixture rich, OUT to lean. It takes some time, but you'll get it eventually.👍


Rich, I think you might be on to something. I've taken both the Idle and the main needle adjustments in all the way and then backed them out 1 turn thinking that they would be lean in. I'll have to take the main needle out tomorrow several turns and see if that helps.

Thanks for the tip.

Larry
Larry Rolla
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Sat, Nov 27, 2010 2:49 PM
dpendzic
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Reply to lrolla:


Rich, I think you might be on to something. I've taken both the Idle and the main needle adjustments in all the way and then backed them out 1 turn thinking that they would be lean in. I'll have to take the main needle out tomorrow several turns and see if that helps.

Thanks for the tip.

Larry
Larry---the main jet adjustment is different depending if you have a horizontal or vertical screw adjustment. horizontal in richins the mixture and verical out richins the mixture
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Sat, Nov 27, 2010 9:38 PM
STEPHEN
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Reply to dpendzic:
Larry---the main jet adjustment is different depending if you have a horizontal or vertical screw adjustment. horizontal in richins the mixture and verical out richins the mixture
Even if the Carb adjustment is off, it should hit a time or two. How about if you shoot a bit of ether? or give it a drip of gas down the pipe?
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Sat, Nov 27, 2010 10:16 PM
SSsssteamer
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Reply to STEPHEN:
Even if the Carb adjustment is off, it should hit a time or two. How about if you shoot a bit of ether? or give it a drip of gas down the pipe?
Be careful with using ether on the pony motor to start it. You're better off not to use ether on the pony motor at all. Instead, use gasoline or maybe a squirt of WD 40 in the pony to start it. I once blew up my pony motor on my D8 14A by using ether. It didn't get past TDC when it fired and when it kicked back, everything got twisted up inside. The carnage wasn't pretty.That was an expensive lesson for me. It cost me over $3,500 for NC Machinery to rebuild it. Not finding all of the needed replacement parts was the biggest problem for the huge expense. Even my pony's electric starter motor bendix was destroyed in the kick back.
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Sat, Nov 27, 2010 10:46 PM
lrolla
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Reply to dpendzic:
Larry---the main jet adjustment is different depending if you have a horizontal or vertical screw adjustment. horizontal in richins the mixture and verical out richins the mixture


This is what I love about this website. The information never stops flowing. I have the horizontal adjustment and only have about a turn out on it. Based on the information, I'm giving it way too much gas. I so excited to see if this is the problem that I'm headed out there in the rain right now.

Thanks,

Larry
Larry Rolla
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Sun, Nov 28, 2010 12:10 AM
lrolla
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Reply to SSsssteamer:
Be careful with using ether on the pony motor to start it. You're better off not to use ether on the pony motor at all. Instead, use gasoline or maybe a squirt of WD 40 in the pony to start it. I once blew up my pony motor on my D8 14A by using ether. It didn't get past TDC when it fired and when it kicked back, everything got twisted up inside. The carnage wasn't pretty.That was an expensive lesson for me. It cost me over $3,500 for NC Machinery to rebuild it. Not finding all of the needed replacement parts was the biggest problem for the huge expense. Even my pony's electric starter motor bendix was destroyed in the kick back.


Ouch! I'm going to keep this information in my back pocket. Someone told me that the starting fluid today is not what it used to be. Either way, I'm sticking with gas.

Larry
Larry Rolla
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Sun, Nov 28, 2010 12:13 AM
zootownjeepguy
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Reply to lrolla:


This is what I love about this website. The information never stops flowing. I have the horizontal adjustment and only have about a turn out on it. Based on the information, I'm giving it way too much gas. I so excited to see if this is the problem that I'm headed out there in the rain right now.

Thanks,

Larry
[quote="lrolla"]This is what I love about this website. The information never stops flowing. I have the horizontal adjustment and only have about a turn out on it. Based on the information, I'm giving it way too much gas. I so excited to see if this is the problem that I'm headed out there in the rain right now.

Thanks,

Larry[/quote]
I figured you had the horizontal needle adjustment based on the year of your D2. Don't know what the Cat engineers were thinking with that little bellcrank box. It's not like it makes adjusting the carburetor any easier because the needles are still inaccessible.

Generally, if an engine is flooded to the point where the plugs are wet with gas, starting fluid will just make it worse.
Rich Salvaggio
D2 5U9917
'46 Willys CJ2A Farm Jeep, '39 Buick sedan, '49 International KB-7, '37 Allis Chalmers WC, Cushman Scooter(s)
Antique garden tractors & outboard motors
Other rusty old junk comes & goes without warning.

The 2 most useful tools to have in your shop are a Crystal Ball and a Magic Wand
Please log in or create an account to join the conversation.
Sun, Nov 28, 2010 8:28 AM
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