JD H Carburetor Adjustment

JDHDon · Aug 8, 2018

I'm struggling to get my hand crank H running well after sitting all winter (yes, winter is long gone). My usual starting procedure is to barely open the throttle lever and go to full choke. After a couple of pulls on the flywheel, engine starts to run and I let it run for a few seconds on full choke and then back off the choke to full open. Now, if I open the choke past half open, it starts to die and occasionally I get a backfire thru the exhaust. I have new plugs and have removed the carb and cleaned out. I have the idle needle at about 1 1/2 turns and the load needle about 3/4 turn. Any suggestions how to adjust to get back to a nice idle at full open choke and low throttle?

Mark-Ia · Aug 8, 2018

Did you remove all the brass plugs and use drill bits to clean the passages thoroughly? If not your H probably won't idle or run as it should.

RandyB(MI) · Aug 8, 2018

I agree with Mark,below. It has rusted shut in the idle passage. The backfire is combination of lean mixture and needing choke to keep running which puts raw fuel into exhaust and a mag tractor fires on exhaust stroke also. It will self diagnose in this manner. Open load one turn and idle two and start up and throw to open throttle ( fast idle) and while it's up there, close load needle. It will probably stall out. Means it will not run on idle circuit like it should. It needs load fuel to fast idle , which it shouldn't. Should run smooth at WOT after closing load needle. If not, needs correct re-built. I do them if interested.

JDHDon · Aug 9, 2018

(quoted from post at 15:40:58 08/08/18) Did you remove all the brass plugs and use drill bits to clean the passages thoroughly? If not your H probably won't idle or run as it should.

Thanks. I have not tried to remove the brass plugs. I'll give it a try and see what happens.

RandyB(MI) · Aug 9, 2018

You will probably need an acetylene brazing tip to heat them and then let cool to get them out without breaking the slot out of them. then you need a # 40 (6" long) drill bit, a # 53 and a # 58 in order to drill out the passages under those screws and pin ports in throttle end of carb by throttle plate. Probably new throttle shaft bushings and throttle plate. They all wear out and leak air and cause lean condition also. This is why you can't just "put a kit in it " like most try to do. Not on these.

JDHDon · Aug 13, 2018

(quoted from post at 21:23:09 08/09/18) You will probably need an acetylene brazing tip to heat them and then let cool to get them out without breaking the slot out of them. then you need a # 40 (6" long) drill bit, a # 53 and a # 58 in order to drill out the passages under those screws and pin ports in throttle end of carb by throttle plate. Probably new throttle shaft bushings and throttle plate. They all wear out and leak air and cause lean condition also. This is why you can't just "put a kit in it " like most try to do. Not on these.

I was able to remove most of the brass screws. The only ones I couldn't get to were the 2 behind the flange to intake manifold. With that, I did as suggested and it died when I closed the Load valve....so I'll be happy to send the carb to you to take a look at it, clean it, etc. I think most of the bushings etc. are OK but take a look. How much would you charge and what is your shipping address?

JDHDon · Aug 15, 2018

Randy - would consider sending my carb to you...need your contact info.

JD H Carburetor Adjustment

JDHDon

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Mark-Ia

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RandyB(MI)

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JDHDon

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RandyB(MI)

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JDHDon

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JDHDon

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