Skip the auto shop - Our mechanics make house calls

Q: 2 stroke 250 cc Yamaha When at low rpm engine works ok .higher rpm engine bogs

asked by on

Cleaned carb ,changed fuel filter . is it diaphragm in fuel pump, seems ok, not clogged

Hi There, Assuming we are talking about a Yamaha YZ 250 (not sure of year, but it should not matter in this case), it sounds like you may have a fuel starvation problem at high engine speeds. The high speed load screw (also sometimes called the power adjusting needle or main adjusting needle) controls fuel flow at high speed or under full load. This should be adjusted only when engine at normal operating temperature to avoid changes in how the fuel is vaporized at various temperature changes (i.e. fuel atomizes differently when cold vs hot). If this is not properly adjusted, your motor is essentially starving for fuel as you twist the throttle. I would recommend taking this to your local motorcycle shop to have this properly tuned as this can be a bit tricky on a two stroke engine which can result in a lean motor. This type of condition can eventually cause the motor to seize up.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  • Home
  • Questions
  • 2 stroke 250 cc Yamaha When at low rpm engine works ok .higher rpm engine bogs

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.