jd 50 running on 1 cyl

[monzanick]

Sooooo heres the deal. I'm 150 miles away and my dad tells me his 50 is only running on one. he thinks its compression. He has already tried ALL the spark stuff. he has even got shocked a few times by "testing the spark" LOL Well he popped off the valve cover to see if any valvetrain is out of postion. all looked o/k. he turned the engine over with the cover off an watched everything move- he said it was all good. He even checked the valve lash- which was all o/k as well.
I know this is hard going on third hand information but anything common on these old girls? the garden is neglected and the driveway will need to be plowed this winter.

History: 25 years ago, threw a rod bearing. pops bought all parts, 15 years ago I reassembled with reman crank, oversized bearings and new rings(previously overboared .040) The head was cleaned by me and slapped on without valvejob. I thought I did pretty good putting the puzzle back together back then, but now I'm second guessing myself...

[jtrichard]

DID you do a compression test? if you have bad comp. in one cly. i would think you should be able to hear it quite well when cranking it over ..any trouble with getting the pistons back in?(broken rings?) did you pull the valves and at least lap them? did you mix the valves from one cly. to the other? and just so you know the crank bearings are UNDER sized not over

[Willyr]

Easy to do, and I did it in a model T once, left the rings in line, I didnt stagger the ends. Terrible compression. Only would start after maybe 15 mins of cranking. Took the engine apart, set the rings accordingly, never had a problem getting it to start there after.

[Lavoy]

Swap the plugs from side to side just for the fun of it.
Lavoy

[monzanick]

According to pops he has swapped plugs side 2 side, wires side to side an he thinks its in the engine. No compression test has been done yet, dad can't find his tester.

The head was literally cleaned of any gasket material and slapped on as a unit, no disassembly.

Just to clarify, the crank was cut, the connecting rods were remanufactured but to take up the space, there is bigger bearings (thicker). no need to bust my balls over your "take on things"

btw it has run great for 15 years but i cant help but wonder.

Thanks for any ideas!

[Lavoy]

It would seem odd that it would be so low on compression that it won't even fire on that side.
Lavoy

[rpowell]

Don't overlook your manifold . They can really cause some crazy problems . I found out the hard way. Had a miss on a jd 50 also. Manifold was rusted on inside from intake to exhaust .

[monzanick]

I managed to get up to my dads house to look at this old girl. Compression was 100lbs on each side. I checked spark- sweet on both sides. swapped plugs- same old. pulled the intake tube off the front of the carb with it running, rust evident in the bores. while it was running i sprayed starting fluid down dead side, she started popping right along. ripped the carb off and cleaned out all the jets with a tip drill and compressed air. after that it ran pretty well save the bowl gasket leaking like crazy and the generator not charging... well one thing atta time, right.

So I figgured that all the crap got in the carb from when my dad changed the sediment bulb/fuel shutoff last fall. it stirred up the rust in the bottom of the tank/line and settled down in the carb.

Now ta get a carb kit and fix the generator..

Woo!

[Willyr]

There is a fuel screen that prevents sediment from the tank to get to the carb where the fuel line enters the carb. If that is missing then that is why you have crap in the carb.

[digitup2]

Tell him to take one more jolt for the team and see if it is timed right !!The old Deere could be out of time firing on the back side so he should yell when he notices it Tell him shock therapy dose you no good Digitup.

[monzanick]

I figgured the rust came from a couple o- places. one being the fuel shutoff being changed and I believe the screen being rattled around. the other is the air intake tube gasket was missing a piece on the top, you could see a rusty trail running down the gasket face. he plows snow with it so I could see where the snow would get on top of there and melt down into the air intake and rust up the old carb.

pops was too chicken ta check the spark with his fingers again. ;P