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There are no magic bullets here. The crank and case have seen their day. If you can live with the oil leak, by all means do so. Will it also let air into the engine? It might a little, but it’s hard to say if it will be enough to affect the engine operation.
 

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Discussion Starter · #63 ·
Well to be honest I'm not even really hooked on these things yet. I'm not opposed to fixing this and fixing it right but it's not like I need it. I just thought it would be neat to get one of my grandpa's mowers going again.

So basically yeah, if this isn't affecting the way it runs, it's not all that important to me- yet. But it may get there.
 

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Discussion Starter · #64 ·
I've been reading a lot about these and I'm really liking the bore the bottom out for needle bearings idea, pending the crank not being too badly worn. Also the 2 ring piston and needle bearing rod that lets you use a 32:1 mix? Idk, still wrapping my mind around all this stuff. Point being, it's not scaring me away.
 

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I had mentioned about reading that someone had installed a double crankshaft seal by seating the first one and then installing another on top. The theory here being two fold. First, two seals should, in theory, provide extra sealing. Second, when installing the second seal you are installing the second on a section of crankshaft that has not had a seal before. If the crankshaft has wear in the area of the original seal then the second seal should ride in an area that has no wear. I would guess a person would have to measure the depth of the seal area to see if 2 seals could go, one on top of the other. The second one may not sit flush with the crankcase. Compared to the bearing install and piston and rod upgrade, the seals are a cheap test . Bill
 
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I had mentioned about reading that someone had installed a double crankshaft seal by seating the first one and then installing another on top. The theory here being two fold. First, two seals should, in theory, provide extra sealing. Second, when installing the second seal you are installing the second on a section of crankshaft that has not had a seal before. If the crankshaft has wear in the area of the original seal then the second seal should ride in an area that has no wear. I would guess a person would have to measure the depth of the seal area to see if 2 seals could go, one on top of the other. The second one may not sit flush with the crankcase. Compared to the bearing install and piston and rod upgrade, the seals are a cheap test . Bill
Thanks for reminding about setting those seals deeper in the recess. I ended up just driving the lower seal of my 7269B to the bottom of the recess to get to the cleaner portion of the crank. It worked good!
 

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Discussion Starter · #67 · (Edited)
Thoughts on carb overhaul kits? This one certainly looks like it would work but doesn't say it's for the D406 for some reason: (edit: I hadn't seen the edited post explaining in detail that my carb has been replaced, makes sense now)
Font Circle Number Symbol Pattern


What is the OEM part number for the carb kit for mine? Unless I'm just overlooking it I couldn't find it on any of these parts sites that have the exploded views. I still think I could just get by with a new float and keep using the gaskets I have but why not check that box too.
 

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Discussion Starter · #69 · (Edited)
New float came in today, doesn't seem right. It's clamped onto the cork too far out compared to the other one:
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So it seems like it's too close to the housing in the center
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And it rubs, if I mess with it I can get it to stick on the housing like this
Automotive tire Motor vehicle Wheel Tire Toy


So I bet this can happen when fuel is pushing up on it. I tried it out anyway, ran good for about a second then started acting like it was running out of fuel again. So I removed the carb and there was what looked like some sand in the bowl this time.
Automotive tire Alloy wheel Bicycle part Automotive wheel system Rim


Sprayed that out and reinstalled it, ran really good so I shut it down and put the shroud back on thinking I was actually going to get to mow with it. Then when I started it it just idled really low, oh and when I messed with the high speed mixture screw it ran better with it all the way in, though still really low rpms. And if I pushed the primer in it would make it want to die. My best guess at this point is that it's flooding because the float still isn't working properly. I thought it was an OEM one but it obviously isn't.

Oh and when it was running really low rpms it was smoking noticably more than any time before if that means anything
 

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Hmmm ..Maybe it would be a good idea to put a fuel filter in the line if there is room.
Also maybe you would be able to unclamp the float and move it further back.
 

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Okay I went out to the garage and measured all the floats I have. 5 new cork floats and 4 used ones. They are all dead on 2 1/8 inches from the center of the hinge pin hole to the far side of the float. Measure yours to see if it is over. Most of mine looked crimped pretty close to the cork. Bill
 
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Discussion Starter · #72 ·
Hmmm ..Maybe it would be a good idea to put a fuel filter in the line if there is room.
Also maybe you would be able to unclamp the float and move it further back.
I do have an inline filter actually. After it was suggested that I ditch it I noticed the one on the shutoff valve in the tank was dislodged and floating around in there so I'll need to keep it until I fix that at least, but it wasn't restricting flow anyway.

I was worried about messing with moving the brass piece because I read that if gas gets past the coating on the cork it can soak into the cork and mess with how uh, floaty it is. But if that can be done then I'll keep it in mind. Couldn't a feller dip one of these in redkote or some kind of gas tank sealer?
 

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Discussion Starter · #73 ·
Okay I went out to the garage and measured all the floats I have. 5 new cork floats and 4 used ones. They are all dead on 2 1/8 inches from the center of the hinge pin hole to the far side of the float. Measure yours to see if it is over. Most of mine looked crimped pretty close to the cork. Bill
Ok cool, next time I have it apart I'll see what it is at. So I can just reclamp this thing and it will still function properly? It does look like it was sealed before they clamped it.

I do have this pic of them side by side but I can't tell any difference from that so I'll have to check it later.
 

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I have used something I got at the hobby store. It is used on gas engine planes when applying the silk or paper to the balsa wood frame. I call it model airplane dope. A clear, fuel proof coating. Bill

Something like this.

 

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Discussion Starter · #75 ·
So I decided to go back to the basement work bench and disassemble this thing again to see if anything jumped out at me. I was looking at the reeds and they seemed good to me, then I started looking at the gaskets and I noticed that the imprint on one of them sort of faded away for lack of a better phrase. I put the carb body up against the reed valve body and they appeared convex to each other. I could literally rock them up and down off the mounting points.

Like with the Briggs I was working on recently I sanded them flat on my slab of granite with 400g psa:
Body jewelry Bicycle part Font Wood Jewellery


Hand Gear Finger Bicycle part Crankset


Automotive tire Crankset Motor vehicle Rim Bicycle part


That had to have been a big vacuum leak. But I'm not getting my hopes up until this thing consistently runs properly so I went out to reinstall it not expecting much, and as expected it didn't change anything. Still doing the same stumbling as though it's got fuel starvation.

Then it inexplicably just started running really well. Relatively consistently too. I hurried up and mowed with it and it did pretty good even though it was a little smoky. Then it would die and do the stumbling thing again, then for no reason what so ever would come to life again.
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So I don't really know what to think. It's better, but we're not quite there yet on it.

Oh and the dang recoil broke so that topped off the night perfectly:
Road surface Wood Asphalt Automotive tire Wall




 

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Then when I started it it just idled really low, oh and when I messed with the high speed mixture screw it ran better with it all the way in, though still really low rpms. And if I pushed the primer in it would make it want to die. My best guess at this point is that it's flooding because the float still isn't working properly. I thought it was an OEM one but it obviously isn't.

Oh and when it was running really low rpms it was smoking noticably more than any time before if that means anything
When it continues to run rich with the mixture screw all the way in it almost has to be getting extra fuel through the primer circuit. Glad you pressed the primer while it's stumbling, if it's running lean it should pick up when you prime it, but yours is wanting to die and is smokey, so yeah running rich and unable to lean it out is typical for a D-400 with a faulty primer. The little red seal at the end of the plunger is what fails and allows too much fuel up to the venturi. This is real common on D-400s that have some age.

Edit: Unfortunately that little red seal is not replaceable, you will have to replace the entire plunger assy. The good news though is that you won't have to take dikes and cut retainers off just to get the plunger out. I think I remember seeing a replacement plunger on yours, so all you will need to do is remove the cotter pin and little plastic cap and pull the plunger through the bottom. The new plunger assy will have instructions with it to show you exactly how the it goes back together.
 

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Rex beat me to the primer issue. Glad he brought it up again. I had mentioned the primer originally but it was kind of glossed over as it is the new style. I have had 2 of those D-400 series, one was a Bricktop edger and the other a mower, that I thought the rubber on the primer looked okay. Started and smoked like crazy and couldn't dial it in. New primers and they ran perfectly. The smokey nature makes me lean back toward replacing the primer. Bill
 

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Rex beat me to the primer issue. Glad he brought it up again. I had mentioned the primer originally but it was kind of glossed over as it is the new style. I have had 2 of those D-400 series, one was a Bricktop edger and the other a mower, that I thought the rubber on the primer looked okay. Started and smoked like crazy and couldn't dial it in. New primers and they ran perfectly. The smokey nature makes me lean back toward replacing the primer. Bill
Yeah I was going to give you credit for it because I remember you mentioning it back on the first page of this thread, but it slipped by me.
 

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Discussion Starter · #79 ·
New primer assy and recoil pulley part are on their way. I still don't fully comprehend why it sounded like fuel starvation before and now it's crazy rich. But hey, if I can actually get this sorted out it'll be quite rewarding considering how demoralizing it's been every time I expected some new part to fix it. Certainly learning a lot too.
 

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Discussion Starter · #80 ·
They are all dead on 2 1/8 inches from the center of the hinge pin hole to the far side of the float. Measure yours to see if it is over.
This one is 2 3/16" from center of hinge pin to far side of float. Doesn't sound like much but if it was just 1/16" closer it sure wouldn't be rubbing on the center housing. So just recrimp it closer and get some airplane dope or similar to coat over the old and new holes ya think?
 
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