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Glad you figured it out. for sure if the kill wire was being grounded against any metal on the engine it would shut down the motor. Also the other wire you mentioned going to the anti backfire solenoid might of bean shorting out at the same time.

Sounds like you got it figured out & found the culprit. Thanks for updating the thread.
 
I've got a couple of old riders. I rewired them. Toggle switch on/off for the ignition. Flipper switches from old weed trimmers for the starters, fuel cut solenoids have been neutered. I left the safeties working for the clutch and neutral. Not having all the safeties working is a good excuse to not loan them to anyone, also saying NO works pretty well.
 
Discussion starter · #24 ·
I've got a couple of old riders. I rewired them. Toggle switch on/off for the ignition. Flipper switches from old weed trimmers for the starters, fuel cut solenoids have been neutered. I left the safeties working for the clutch and neutral. Not having all the safeties working is a good excuse to not loan them to anyone, also saying NO works pretty well.
I tend to like safety switches. Handy in the event I get ahead of myself and fail to pay enough attention to what I’m doing.
The mower switch had been disabled by a previous owner. It also serves the snowblower attachment when its mounted. I didn’t feel comfortable with that one being disconnected and I couldn’t really figure out where it was. One case where parts diagrams and lists didn’t help. But, MTD’s customer service line came to my rescue and told me what to look for and where it was supposed to be. Knowing what I was looking for I managed to find it zip tied down and zip tied up under the frame out of sight. So it is back where it is supposed to be and working as it should.
So far as wasting money on parts, well, it’s nice some time to have back ups on hand.
 
Discussion starter · #25 ·
Well heck! Back in post #20 I proudly announced that I had figured out the problem.
The little salvage yard find ran fine the remainder of the mowing season and never missed a beat through the winter snow blowing season.
Started the new mowing year by replacing the oil and a new air filter and pre-filter.
Mowed liked nobody’s business. But, went out for the second mow and the old gremlin showed up!😡
Started acting like it was out of gas, which it wasn’t. Full tank of fresh gas. Checked the gas cap. Blew air through it and loosened it. Sitting still at full throttle range from idle to wide open. Narry a bobble.
Engage the mower deck and it spits and sputters until it almost dies. Disengage the deck and it returns to running fine.
I went through this routine a few times until I decided to give up and get the freebee Toro Recycler out. I guess I needed the exercise anyway.
After sitting a bit, I hopped on the rider to take it back to the garage. While enroute it did the same as before. Run fine, then out of the blue act like it’s out of gas.
This time, out of frustration and not wanting to push or pull the Yard Machine the rest of the way, I yanked the choke lever.
Hmmm…it seemed to do better. Fiddling with the choke position the rest of the way home got me back to the garage.
Looks like another carb cleaning in the works, but I’m going to go over the wiring again too.
🫰🙏Let’s hope things work out. I actually kind of like this thing even though it frustrates me at times.
 
Discussion starter · #26 ·
Well, here we go again.
I visited a local salvage yard and pulled the portion of the wiring harness off of another mower to replace the one I had pinched.
Put the new O-ring in between the air box and carb body.
Gave everything another once over and set off to mow. It actually seemed to start easier, or maybe that was wishful thinking.
I didn’t time how long I mowed, but it was long enough to burn off half a tank of gas. It ran like a champ until…
Suddenly it started its routine of sounding like it was running out of gas while mowing. Usually that only happened when trying to engage the deck. So I stopped and let it clear itself, but, you guessed it, bogged and refused to run trying to engage the deck. Took a look and yep, half a tank like I said.
Oddly it would run OK between idle and half throttle so I limped back to the garage.
So now my thinking was that there must be some issue with the main jet.
Tore into it today…again…nothing to be seen. By the way, I really hate that stupid main jet in the Nikki carb that always falls out when you take this thing apart.
So, after putting it back together, using that weird rubber seal that Nikkis have from the carb replacement I got and turning the fuel shut off back on gas came pouring out from everywhere!
Holy crap! Now the cylinder is full of gas. Pulled the spark plug and turned it over to purge the gas from the cylinder. And the oil on the dip stick smells of gas!
So another oil change and oil filter are in the works.
So, anyone out there have any suggestions? What the heck gets into this thing to run fine for extended periods then suddenly not want to run at all?
 
Well, here we go again.
I visited a local salvage yard and pulled the portion of the wiring harness off of another mower to replace the one I had pinched.
Put the new O-ring in between the air box and carb body.
Gave everything another once over and set off to mow. It actually seemed to start easier, or maybe that was wishful thinking.
I didn’t time how long I mowed, but it was long enough to burn off half a tank of gas. It ran like a champ until…
Suddenly it started its routine of sounding like it was running out of gas while mowing. Usually that only happened when trying to engage the deck. So I stopped and let it clear itself, but, you guessed it, bogged and refused to run trying to engage the deck. Took a look and yep, half a tank like I said.
Oddly it would run OK between idle and half throttle so I limped back to the garage.
So now my thinking was that there must be some issue with the main jet.
Tore into it today…again…nothing to be seen. By the way, I really hate that stupid main jet in the Nikki carb that always falls out when you take this thing apart.
So, after putting it back together, using that weird rubber seal that Nikkis have from the carb replacement I got and turning the fuel shut off back on gas came pouring out from everywhere!
Holy crap! Now the cylinder is full of gas. Pulled the spark plug and turned it over to purge the gas from the cylinder. And the oil on the dip stick smells of gas!
So another oil change and oil filter are in the works.
So, anyone out there have any suggestions? What the heck gets into this thing to run fine for extended periods then suddenly not want to run at all?
That's because many, if not most of the Nikki's were installed incorrectly from the factory at least I say so .
When you put the jet in at the bottom it can fall out up until you get the bowl all the way and it's proper position and if it does or run excessively rich.
Then of course you have the problem you're dealing with now who are the Nikki's don't shut off properly and that could just be a piece of fuzz or hair is in the inlet needle and seat but sometimes you have to end up replacing at least the plastic guts inside to get them to stop leaking.

Regardless, here is the best way and what I call the proper way to install the main jet. When you have the carburetor apart you will drop the main jet into the center of the plastic tube from the top and let it fall to the bottom..
You then have to make sure it is lined up properly and I usually use a skinny Phillips screwdriver to push it all the way in so the o-ring is sealed.
Then, when you put the bowl and the white plastic internals onto the carb body, the tube down the middle will hold the seat into place properly so it can never lift up again.
I can't tell you how many I've taken apart for the jet was pushed in from the bottom and that's just ridiculous.
I do not prefer the Nikki design at all. Give me a good old walbro where I can pull the brass seat out and replace that and the needle valve with brand new parts from Briggs for six or seven dollars and the whole thing is much simpler with only a bowl gasket.
Not only is Nikki more complicated and has a ridiculously complicated gasket, there are two of them!!
They do not interchange it's ridiculous..
 
I
That's because many, if not most of the Nikki's were installed incorrectly from the factory at least I say so .
When you put the jet in at the bottom it can fall out up until you get the bowl all the way and it's proper position and if it does or run excessively rich.
Then of course you have the problem you're dealing with now who are the Nikki's don't shut off properly and that could just be a piece of fuzz or hair is in the inlet needle and seat but sometimes you have to end up replacing at least the plastic guts inside to get them to stop leaking.

Regardless, here is the best way and what I call the proper way to install the main jet. When you have the carburetor apart you will drop the main jet into the center of the plastic tube from the top and let it fall to the bottom..
You then have to make sure it is lined up properly and I usually use a skinny Phillips screwdriver to push it all the way in so the o-ring is sealed.
Then, when you put the bowl and the white plastic internals onto the carb body, the tube down the middle will hold the seat into place properly so it can never lift up again.
I can't tell you how many I've taken apart for the jet was pushed in from the bottom and that's just ridiculous.
I do not prefer the Nikki design at all. Give me a good old walbro where I can pull the brass seat out and replace that and the needle valve with brand new parts from Briggs for six or seven dollars and the whole thing is much simpler with only a bowl gasket.
Not only is Nikki more complicated and has a ridiculously complicated gasket, there are two of them!!
They do not interchange it's ridiculous..
do this every day Nikis are Junk Give me a Warlboro any day.
 
Discussion starter · #30 ·
I tried to do just that using the B&S part number for the Walbro. Unfortunately the Nikki replacement was what I got. Guess that’s what I get trying to go cheap through ebay. The cost to return it and time to do so wasn’t worth it to me.
Since I was able to source the part of the wiring harness at the salvage yard I may go back and look for a Walbro that could work after a good cleaning.
 
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