new 620, questions

carterbeauford · May 16, 2013

picked up a nice original 620 over the weekend, I intend to restore it to work full time on my hobby farm. I'll have a bunch more questions as I tear into it, but for now:

1) if the sediment bowl is not shut off, it gets gas in the oil. it runs rich and smokes. the automatic fuel shutoff has been eliminated, its just a sediment bowl with a line to the carb. the previous owner said it's the needle valve. can I replace this myself? worth sending the carb to Roberts?

2) the 3 point works but drops if I let it sit, I assume the problem is in the ram, how hard is this to fix?

3) it has mismatched oversized tires on it. I read the original size is 12.4-38 which sounds small. I'll be adding flat top fenders, will 12.4-38s leave too much of a gap between the fender and top of tire?

BushogPapa · May 16, 2013

The "Ultimate" tires would be 15.5x38 on 14" rims..

12.4x38 is pretty small, even on a Late Styled JD "B"
See if the 3-Point holds position with the tractor running..

You really should have a GOOD Fuel Shut-Off and use it every time you shut of the tractor..

You should be able to R&R the Needle and Seat..

Since you are not having any fuel Starvation issues, the carb should be able to be adjusted..once you get the New Needle & Seat installed.
Enjoy that 620..the are a powerful tractor..!
Ron..

Jethro Lilley · May 17, 2013

First sentence in question #1... if the fuel is not shut off you get gas in the oil... ALWAYS shut the gas off at the sediment bowl EVERY time you shut off the engine. This is true of all of the 2 cylinder models. JD attempted to bypass this rule with an electric fuel shut-off on the bottom of the bowl which worked fine when it worked. I never trusted it on my 730. I've heard tales of a crankcase full of gas blowing up upon starting the tractor. Right there between your legs.
I had 15.5-38's on the 730. I would not use less than a 13.9 on a 620. I agree that 15.5 would be optimal and should pose no problem with flat-tops.

Kent Petersen · May 17, 2013

Deere never used an elec.fuel shut off on a 730 or any 2cyl for that matter, all worked off oil psi you say you heard stories ,they are just that

Kent Petersen · May 17, 2013

just to add to my comment on fuel shut offs deere did us elec on propan tractors

carterbeauford · May 17, 2013

thanks for the advice. here's a picture of the day I brought it home.

2 chains and 2 5500lb straps and I blocked the wheels with oak blocks screwed into the deck for the securement police.

Hugh McKinney · May 17, 2013

That's right, my LP gas 70 came with an electric "Fuel Strainer" and shut off (which still works!)My Uncle's LP 730 had it too.

MikeinKy · May 18, 2013

Original tires on most was 13.6-38. i have 14.9-38 on mine and like them better.

carterbeauford · May 19, 2013

(quoted from post at 04:14:06 05/17/13)
See if the 3-Point holds position with the tractor running..

it holds running but leaks down when stopped.

also noticed the PTO clutch doesn't work.

are the hydraulic couplers the "old style" John Deere?

carterbeauford · Aug 31, 2013

got the shop manual, if I'm going to repair the lift cylinder, are there any other parts I should order other than the o-rings and rockshaft seals?

Pitalplace · Aug 31, 2013

Be aware that you don't have to take out the rock shaft to replace the o-ring and paper seal on the lift piston. It will come up far enough to remove from cylinder.

new 620, questions

carterbeauford

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BushogPapa

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Jethro Lilley

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Kent Petersen

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Kent Petersen

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carterbeauford

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Hugh McKinney

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MikeinKy

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carterbeauford

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carterbeauford

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Pitalplace

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