My Beta 250 2003 makes slappings at the time or slow down the accelerator, engine hot. These slappings make me think of auto-ignition. The level of tank of the carburettor is good, jets 150 and 31, the spark plug is normal, the engine is powerful.

If somebody knows a solution, thank you to indicate it to me.

has it just started doing this?

search the forums under 'pinking beta'

Dear BATRIAL

My 2003 REV3 200 used to make the same noise at the same time as what you described; just as the throttle is snapped shut. I tried different fuels, different jetting ie needle position, needle shape, pilot jet size, main jet size, float height, spark plug temperature rating and oil/fuel mix ratio. When I advanced the ignition timing a bit, the noise you described disappeared.

The place where my bike runs so nicely is with the stator screws in the middle of the adjusting slots.

In case there is confusion about what is advancing the ignition, it means to cause the spark to occur earlier ie to rotate the stator in the opposite direction to the direction the rotation of the rotor.

I hope this is of use to you.

David Lahey

My old 270 used to do this very badly, especially under hard acceleration when the engine was hot. I tried all of the usual things (higher octane fuel, checked the timing etc.) to no avail. As soon as I went one size up on the pilot jet the problem disappeared completely. Might be a good place to start since jets are cheap and easy to change!

Neonsurge

This problem never happened under acceleration hard or gentle. It was when the throttle was being closed and this is what BATRIAL seemed to be saying also. Yes a larger pilot jet will halp with pinging under acceleration but I don't think that is the problem here.

David

Thank you for all your answers concerning my problem of slapping in the engine.

Does somebody know the value of the firing advance in degrees on one 250 Beta 2003?

I wish to control with the idle and high speed with a stroboscopic lamp.

I add that the slapping also occurs with acceleration when the engine increase speed from the idle to an average mode, hot. With full mode there is no slapping and the engine has its normal power.