JD D100 Will Not Start

[PapaDrew88]

So I did an oil and filter change, installed a new spark plug and then I installed my new Nikki carb and heard a few misfires (a small popping) and then a big backfire pop, big plume of white smoke came out the muffler. Still turns over fine but the temp is in the mid 30s so it doesn't take long for the battery to run down.
I assume the Nikki is plug and play? I didn't make any adjustments.

 

[PapaDrew88]

Just finished pulling the head off, cylinder was full of gas. Seems like it is still flooding with the new carb. Cylinder, piston, head, valve springs all look good and valves are seating properly.
I will adjust the valves tomorrow and finish putting it back together. I'll post pics of the piston at TDC and the magnet on the flywheel after dinner.

 

[PapaDrew88]

Here are the pics of the piston and magnet is at TDC and valve springs. The carbon build up looked normal, I cleaned it up a little. The cylinder had no wear.
For some reason I still think it is flooding with the new carb. The cylinder was full of gas as I stated earlier.
Could it be a timing issue and gas is building up in the head and therefore the reason it is not firing?
How do you check timing?
It was a free lawn mower so I'm not giving up. Thanks!

 

[Scrubcadet10]

Small engines are timed two ways.
The flywheel key aligns the flywheel to the crank for proper ignition timing, and then the Cam shaft and crank gears have a dot that must be aligned for proper valve timing

 

[PapaDrew88]

So a little progress, I changed the ignition coil and now it is backfiring like crazy, still not running. Any suggestions?

 

[PapaDrew88]

Small engines are timed two ways.
The flywheel key aligns the flywheel to the crank for proper ignition timing, and then the Cam shaft and crank gears have a dot that must be aligned for proper valve timing

I replaced the magneto coil and now it is backfiring. Still want crank.

 

[Scrubcadet10]

i would check the flywheel key next. you may need to remove the flywheel nut/bolt to see it.
also i read that this JD uses the 31 series Intek, which has had camshaft problems, i remember one where the exhaust lobe was worn down and causing it to backfire and pop.

 

[PapaDrew88]

i would check the flywheel key next. you may need to remove the flywheel nut/bolt to see it.
also i read that this JD uses the 31 series Intek, which has had camshaft problems, i remember one where the exhaust lobe was worn down and causing it to backfire and pop.

Ok I will check the flywheel key again thanks

 

[PapaDrew88]

Ok I will check the flywheel key again thanks

Mfg. No: 31G777-0171-G5 is the engine number.
Checked key way and it looks brand new
I forgot to mention this earlier. So after I changed the magneto coil, the mower fired up and started running for a few seconds and then blew the main fuse. The reason it blew the fuse is because I had blown the 20 amp when I first started working on the mower and replaced it with a 5 amp just so that it would fire ( I didn't have a 20amp replacement).
I took the 20 amp from my other JD LA140 and installed it in the other mower. Once I did that and tried to crank, that is when it started backfiring while it was trying to crank.

 

[PapaDrew88]

I decided to get back on my mower project. It is now sheering the flywheel key once it starts up and runs a few seconds. I'm convinced something is broke internal.