Mystery engine issue i cant solve

[Squirrel Master]

Hello everyone!

(Pictures attached)

I'm trying to fix my neighbors mower for him. He just got a used Ariens zero turn with a Briggs motor. Its in great shape but we cant get the motor to run right. Below is the list of new parts we've put on...

- new carb set to factory specs
- fuel pump
- fuel filter
- spark plug
- filter
- oil and filter
- air filter

The mower is near-impossible to start when cold. The choke/throttle has to be all the way OFF and it backfires through the muffler and carb constantly until it warms up all the way. It WILL NOT start with the choke/throttle up even a little bit. If we can even get it started, once it warms up it runs halfway decent but not perfect. We've fiddled with the carb adjustment screw a lot and nothing seems to make it any better, only worse. We're running out of parts to replace and ideas to fix it. Hence, the forum post. Any ideas or suggestions would be greatly appreciated!

Please let me know if you have any questions or need any additional details. Thanks in advance everyone!

 

[Scrubcadet10]

Engine model and type numbers? usually stamped on the valve cover of OHV engines.

 

[Squirrel Master]

Wow! Thanks for the speedy reply! Sorry for not including that. The valve cover doesnt seem to have it listed. Theres a spot for it but its blank. Does that serial number help? (See attached)

 

[Squirrel Master]

sorry. I'm not sure why the images arent uploading. I was able to find the model number.. 21B807 0130 B1. I believe the type number is 90223ZA.

 

[Born2Mow]

How old is the fuel ? Dump ALL the fuel (tank, lines & carb) that came with the mower. Install new fuel.

Put the old stuff in your car... it doesn't care.

 

[Scrubcadet10]

i would check your valve clearance...

 

[Squirrel Master]

The gas is new. I know thats not the issue. I havent messed with the valves yet. I'll give that a go in the next couple days. Any other ideas before i get into adjusting valves?

 

[Squirrel Master]

Got the valve cover off and the exhaust valve rocker is VERY loose. Im going to measure and adjust but need to make aure im doing it right. I should adjust the valves when they are conpletely closed correct?

 

[Scrubcadet10]

Got the valve cover off and the exhaust valve rocker is VERY loose. Im going to measure and adjust but need to make aure im doing it right. I should adjust the valves when they are conpletely closed correct?

With the Valves Closed, correct.
I've always set them with One valve completely open, and adjust the one that is closed. so if the Intake is down, adjust the Exhaust.

 

[jimbo9999]

i really don't know much about engines but how about the ignition coil (magneto)