The spark plug on my yamaha yz 125 gets too oily and then fouls. what is wrong? thanx?

Question

The spark plug on my yamaha yz 125 gets too oily and then fouls. what is wrong? thanx?

Answer 1

Using the incorrect 2-stroke oil.  Switch to Yamalube 2r or Yamalube 2S synthetic oil in your oil injection tank.  Drain the old oil from the oil injection tank before you add the new oil.  This will most likely correct your problem.

If the new 2-stroke oil does not correct the problem, check the following items.

Spark plug too cold.  

Incorrectly adjusted oil injection pump

Dirty air filter

Carburetor adjusted incorrectly

Answer 2

carb set too rich

choke stuck on

rings shot

Answer 3

Run Yamalube at 42:1. 20:1 is way too rich!

16oz of oil to 5 gallons of gas

Answer 4

There could be several resaons for this.The rings could be worn,do a compression test to check this.check and clean your air filter don't forget to oil it.you may have to clean the carb. p.s.your bike does not have oil injection and it should be mixed at 40.1. If you do not have a ratio rite get one.ask the yamaha shop if you can step up to a hotter plug