How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask J.R. Your Own Question
J.R., Small Engine Technician
Category: Small Engine
Satisfied Customers: 7445
Experience:  Owner of outdoor power equipment business, repairing all makes and models.
Type Your Small Engine Question Here...
J.R. is online now
A new question is answered every 9 seconds

I have a lawn tractor with a 21 HP B&S Vanguard engine. It

This answer was rated:

I have a lawn tractor with a 21 HP B&S Vanguard engine. It has recently developed a rough running problem, spitting and popping blowing black smoke particulary at full throttle. I have changed the plugs and air filter, still the same. Any suggestions?
The problem may be a plugged up jet in the carburetor. I would take the carburetor apart and clean it and then put it back together with a rebuild kit.
J.R. and other Small Engine Specialists are ready to help you
Customer: replied 7 years ago.
should there be a number on the carburetor to use in order to get the correct rebuild kit?

Look on one of the valve covers for all of the model and type numbers. Go to and enter those numbers. It will bring up a parts list that will give you the correct part number.