Small Engines (Lawn Mowers, etc.): back fire, compression stroke, wd 40

Question
Hi Eric,

Ran out follow up questions. First, I like to thank you for all your help. My tractor can start up now with the key. I have to
ground the solenoid. I thought the new solenoid ground itself to
the frame.

About the engine, it sound a lot louder than my old engine.
Especially from the muffler loud and backfire. Also backfire loud
pop when turn off the engine.

Do you think I should clean the Carb? Any links and instructions for cleaning and adjust the carb. Briggs engine 281707 0179-01 88120831 Thanks Tim

Answer
I'd start by cleaning the carb.  There are several videos on You Tube covering carb cleaning.

You engine is a 1988 model so some of the backfiring could be caused by the valves.  

http://engines.myfaqcenter.com/Answer.aspx?p_faqid=3441&body_0$tbKeyword=valves

http://engines.myfaqcenter.com/Answer.aspx?p_faqid=3439&body_0$tbKeyword=valves

I would recommend taking pictures as you remove and dis-assemble the carb.  I'd also buy a carb kit before removing the carb.  Use spray type carb cleaner and air from an air compressor to blow through all the carb orfices.  You will have to re-adjust the carb when you re-install.

http://engines.myfaqcenter.com/Answer.aspx?p_faqid=3353&body_0$tbKeyword=carbure...

With the carb off, you can remove the valve breather and at least check the valve clearance.  You will have to rotate the pistion to top-dead-center on the compression stroke but this can be found by following the valves and inserting a WD-40 or regular drinking straw in the spark plug hole and feeling the piston as it travels up on the compression stroke.  Checking the clearance will give you an idea of the valve condition.

As for the backfiring, it happens on those engines which is why all the engine manufactures started installing anti-afterfire solenoids on the carbs.  You can try idling the engine all the way down when shutting off the engine but you may still get a backfire once in a while.

To recap, in a more organized manner,  remove/clean the carb and check the valve clearance while the carb is off.

Let me know if this helps.
Eric