My Tractor Forum banner
1 - 18 of 18 Posts

·
lawnboys are great!
Joined
·
134 Posts
Discussion Starter · #1 ·
ok so a few weeks back my 5236 d mower was back firing. i changed the plug and all seemed well. i have mowed with it several times on low speed and on high speed. it made no difference it never missed a lick. so yesterday i started cutting and after about 20 min it started to pop and or back fire. i moved the speed to high, but it continued. i then hit the primer to try to keep it running but it finally died.

looking for your suggestions again guys

craig
 

·
Administrator
Joined
·
21,928 Posts
Isn't this the coil that has the 2 sides, for start and run? I had one of these go bad and it would backfire, not rev, run horrible. Put a new coil on it and it works fine. Wonder if you just need to bake the coil?
 

·
Senior MTF Poster
Joined
·
13,553 Posts
"Isn't this the coil that has the 2 sides, for start and run?"

Not this one.

What spark plug are you using? CJ14 I hope. Condenser is a suspect also.

Walt Conner
 

·
lawnboys are great!
Joined
·
134 Posts
Discussion Starter · #5 ·
yes a new cj14 plug.
 

·
Old engine addict
Joined
·
292 Posts
Sounds like the timing advance weight is sticking. I've had a couple old D's do this to me before. Take the flywheel off and lube up the advance weight slide with some white lithium grease.
 

·
lawnboys are great!
Joined
·
134 Posts
Discussion Starter · #7 ·
Sounds like the timing advance weight is sticking. I've had a couple old D's do this to me before. Take the flywheel off and lube up the advance weight slide with some white lithium grease.

i added a thin layer of grease when i had it apart a few weeks back, but it was not white lithium grease . everything seemed to slide around real good when i put it back together.
 

·
Registered
Joined
·
310 Posts
You've just got to love the precision of this factory manual's explanation at
https://lookup3.toro.com/ttcGateway/...ls/lball24.pdf

"The magneto is solely for IGNITION. It provides a
current of sufficiently high voltage (up to 17,000
volts in a Lawn-Boy engine) to cause a spark to
jump the gap between the spark plug electrodes and
ignite the compressed fuel vapor at exactly the moment
when the piston reaches near the top of the compression
stroke."

So they are saying that spark triggering occurs EXACTLY - - NEAR THE TOP OF THE COMPRESSION STROKE."
But that triggering period range description is NOT exact.
This reminds me of a Japanese import clock radio gift I received years ago.
It bore a label stating that its case was made from GENUINE IMITATION wood.
If timing is exact it is not a range. If the case material is genuine is is not imitation.
The best humor is unintentional. I find this factory manual's writing to be unintentionally funny.
John
 

·
Senior MTF Poster
Joined
·
13,553 Posts
"so yesterday i started cutting and after about 20 min it started to pop and or back fire. "

"Sounds like the timing advance weight is sticking."

??

Walt Conner
 

·
lawnboys are great!
Joined
·
134 Posts
Discussion Starter · #12 ·
the last 3 times i cut with it, it ran perfect the whole time i used it about an hour. i have no experience with points, so that's why i am confused. 1 min it runs good then it starts acting up...
 

·
Decesaed (R.I.P.)
Joined
·
1,957 Posts
the last 3 times i cut with it, it ran perfect the whole time i used it about an hour. i have no experience with points, so that's why i am confused. 1 min it runs good then it starts acting up...
Just follow the manual and you'll be fine. Once you understand the points you'll like them, they're a good setup. They just have to be right, just like that whole mess under there, the governor, the flyweight, etc.....
 

·
lawnboys are great!
Joined
·
134 Posts
Discussion Starter · #14 ·
Just follow the manual and you'll be fine. Once you understand the points you'll like them, they're a good setup. They just have to be right, just like that whole mess under there, the governor, the flyweight, etc.....
i will tear into it again in a day or two. thanks for the suggestions!!
 

·
Senior MTF Poster
Joined
·
13,553 Posts
Are you questioning that because the advance works as an all or nothing type device? Either 6deg or 26deg? 6deg before 1000rpm and 26deg after 1000rpm
I am questioning it because in 40 years of using, trading, selling and repairing LBs I have never heard or seen such a thing for symptoms described.

Walt Conner
 

·
Decesaed (R.I.P.)
Joined
·
1,957 Posts
I am questioning it because in 40 years of using, trading, selling and repairing LBs I have never heard or seen such a thing for symptoms described.

Walt Conner
I wasn't arguing with you, after thinking about it, it made sense, that's why I made that statement. After the engine started and the advance kicked in it should stay in and give no trouble. Congrats on 40 years of Lawn-Boyness
 

·
Registered
Joined
·
373 Posts
I've had that advance flyweight stick on a couple old D-400 engines already. They'll rev up to about 1800 RPM, then it's like they hit a brick wall, and won't rev higher. They'll just kind of surge, falter, and backfire, and seem to ignore any fuel mixture or throttle changes.

As for the 6° to 26° BTDC advance, it's not a completely instant change like it would be with a CD ignition system. As the RPMs build, the flyweight advances timing in a quick curve. If a person were really into tinkering, trimmed down flyweights and/or different rate springs could be used to fine tune the advance curve, but this setup works fine when it's working, so there'd really be no advantage to this as far as I see it.
 

·
Decesaed (R.I.P.)
Joined
·
1,957 Posts
Yeah, it's not instant but it's designed to work at 6 or 26 degrees advance, not in between I guess is what I'm gettin at.

The problem is that it mowed fine for 20 minutes. If the flywheight advanced and it ran fine then there should've been no problems after that...until the engine was either shut off or dropped below 1000 rpm
 
1 - 18 of 18 Posts
Top