John Deere BR runs rough

[BrockNewZealand]

Hi All
I have a BR that starts fine and idles fine but when I throttle it up fast or put it under load it wants to Die out and blows black smoke .
I have cleaned carb with drill bits and changed condenser I have tried adjusting needles but no luck also changed plugs no difference. I notice it hunts on the governor linkage.
Also advanced and retarded magneto.
Any insight would be great

Brock From NZ

 

[timcasbolt]

I've had float problems that sounded like that.

 

[buickanddeere]

There are well hidden passages to rod out . Have to remove plugs and balls . The idle passages along the throttle blade bore are invisible unless you know they are there .

 

[buickanddeere]

Valve lash and compression ?

 

[JIM MN]

Try fresh gas ; no ethanol, three or four gallons.. Pour in a can of Seafoam. Go use the tractor on a good pull to heat everything up.. If still no good, are you still getting black smoke, may be a restricted air cleaner. Try loosing the two bolts on front of carburetor; loosen enough to let in air; do not need to take out.. If no help; need more more gas when throttling up under load. Your loading up on gas vapors, Check the carb float level.. Its set too low??

 

[BrockNewZealand]

Thanks everyone for replying.
On thing I have been wondering about was the run timing on the magneto it’s a wico C if it was out could it cause this issue ?
I have adjusted float down from where it was at originally 3/8 down from lip of carb bowl so it’s now lower then spec.
The one other thing I notice is the throttle linkage to the carb is out by 3/8 it’s been made to short so I need to lengthen that to be 1/2 hole out at full throttle.this tractor starts very easily and no real blow by so I doubt it’s down on compression.
Thanks will report back

 

[BrockNewZealand]

There are well hidden passages to rod out . Have to remove plugs and balls . The idle passages along the throttle blade bore are invisible unless you know they are there .

This is a DLTX34 carb I cleaned the tiny whole by the throttle blade is that the one ?

 

[used red MN]

Try fresh gas ; no ethanol, three or four gallons.. Pour in a can of Seafoam. Go use the tractor on a good pull to heat everything up.. If still no good, are you still getting black smoke, may be a restricted air cleaner. Try loosing the two bolts on front of carburetor; loosen enough to let in air; do not need to take out.. If no help; need more more gas when throttling up under load. Your loading up on gas vapors, Check the carb float level.. Its set too low??

Why no ethanol? I don’t think those old things are that particular, other than some say ethanol is hard on some carb parts. Don’t get me wrong I am not an ethanol proponent, I am curious if they even have such a thing in New Zealand.

 

[greenmech]

This is a DLTX34 carb I cleaned the tiny whole by the throttle blade is that the one ?

There is 2 holes by the throttle disc. Also there are 2 holes in the stem that need cleaning. Where ever a brass plug is needs cleaning. Ron MN

 

[NoDakInMN]

You should have a DTLX-10 on a BR. On the linked page you will find Item 27. https://robertscarbrepair.com/carburetor-parts/marvel-schebler-dltx-series/ You need to make sure the holes in this part are clear, for when the surrounding well is filled with fuel under normal operating conditions, it operates as a sort of acceleration pump and provides extra fuel during a sudden demand for an increase in rpm.

This link, https://robertscarbrepair.com/tractor-pulls-good-but-will-not-idle/ will take you to a page showing which passages need to be cleaned out.

 

[BrockNewZealand]

 

[BrockNewZealand]

Hi all I pulled mag off to check witness marks on mag I think this is wrong I think it’s to advanced? I also ran tractor with air cleaner pipe off and same issue .
I also noticed that the RH pet cock was blowing small flames out as it was dark in the shed when I ran it I’m starting to think it’s a magneto timing issue. I pulled carb off to recheck ports and pulled the nozzle it’s all clean to me.
It starts easy and idles well but under load it will bog down and black smoke this would indicate run timing being off ?