430 John deere

clayman · Apr 16, 2022

Hello, Wondering if anyone can give me some advice on this one? I have aquired a 430 2-cylinder john deere. I have given it a complete tune-up Points,rotor,Cap, and timeing with a light but its still seems to run a bit off. When its idling it almost sounds like a hit n miss engine. Gets better when i put it under a bit of a load. I dont have a lot od experience in the 2 cylinder engines so wondering if they are supposed to run like that? and if not is there anything else i can check into?

Thanks for now

wore out · Apr 16, 2022

(quoted from post at 10:54:57 04/16/22) Hello, Wondering if anyone can give me some advice on this one? I have aquired a 430 2-cylinder john deere. I have given it a complete tune-up Points,rotor,Cap, and timeing with a light but its still seems to run a bit off. When its idling it almost sounds like a hit n miss engine. Gets better when i put it under a bit of a load. I dont have a lot od experience in the 2 cylinder engines so wondering if they are supposed to run like that? and if not is there anything else i can check into?

Thanks for now

Dunno what it sounds like, or what your experience is with them, but they are "uneven-firing" just like their bigger, horizontal-cylinder siblings and DO have an "odd" exhaust sound vs. tractors with four-cylinder engines.

With the large 2-cylinders, DEERE eventually went to a duplex carburetor to get even fuel distribution to the cylinders, which is always a problem with uneven-firing engines with single-barrel carburetors.

Yours (of course) has a single-barrel carb and "settling down under load" is probably normal, at least to some degree.

Willow Lane · Apr 16, 2022

They do sort of sound like a hit n miss engine. It's a fact of life with a 2 cylinder 4 stroke engine. With any 4 stroke engine, it takes 2 complete rotations of the engine for a complete cycle, so on your engine the first cylinder fires and 180 degrees later the second cylinder fires, then it coasts for 540 degrees until the first cylinder fires again and the process repeats so it's putt-putt---------putt-putt--------. It's just the way it is. If you tried to get it to fire once every 360 degrees, both pistons would be going up and down at the same time and balance would be impossible. The reason you notice it on the JD's more than other 2 cylinder engines is that they turn so much slower than others

jCarroll · Apr 16, 2022

Use a screwdriver - or similarily insulated steel tool - and short out the plugs one at a time when it's warmed up and idling. Use your ears to see (listen) if it runs the same on each cylinder. If not, follow the problem - valve adjustment, manifold leak, whatever.

Steve@Advance · Apr 16, 2022

Might check the valve clearance, then run a compression test.

Not looking for a particular number, just want to see them close to the same.

sms · Apr 16, 2022

My brother still has our dad's 40C. It always idled like a hit and miss. Other people thought it was going to stall it coasted to such a slow RPM then went pop, pop,pop. It would idle like that all day and worked just fine under load.

Russ from MN · Apr 16, 2022

Willow, there are many 2 cylinder 4 stroke engines that the pistons do go down together, and they actually run quite well. I have driven Triumph motorcycles for 50 years, and on most of the twins the pistons travel together, offset by a counterweight on the crankshaft. They run well up to 7,000 rpm or more, and Honda used that design, and some of their engines run over 10,000 rpm. The one problem with that design is you get crankcase pumping, and it's harder to meet emission standards.

cushman · Apr 16, 2022

I also wonder if your idle circuit is plugged.The engine should settle down to a steady idle of about 400 RPM if the idle circuit is functioning like it should.

430 John deere

clayman

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wore out

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Willow Lane

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jCarroll

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Steve@Advance

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sms

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Russ from MN

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cushman

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