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Backfiring Montesa 4RT


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My bad I should have said ECU not CDI.  

The Montesa does have a standard AC alternator (USA verbiage vs UK verbiage) .  

It also has an AC  "pulser" (see attached Montesa schematic) or trigger coil beside the alternator.

While the alternator is making AC voltage the pulser AC coil (trigger coil) is telling the bike when to fire (adjusted by the ECU & CDI box etc.  

When the bike is running pulling the lanyard sends a ECU pin to ground telling it ignore the Pulser (trigger coil and does not send signal to the CDI box and high voltage coil.

When the bikes running and in gear when you put too much load on the back wheel at low rpms it stalls the engine.

When the bike stalls the AC trigger coil no longer ses a rotation AC pulse going in the ECU box so it kills the bike. 

This scenario can be the same on a 2T carbed trials bike. Too low an RPM  in gear and a heavy sudden load can cause a mechanical stall of the bike as it does not see any AC voltage coming from the alternator and pulser trigger coil to the ECU unit. 

I still think it is weird logic Jimmyl is stating.

I do agree stopping the bike I gear with the clutch is a bad thing to do but purely from a mechanical stress level. 

Montesa .png

Edited by billyt
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