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Louie, Technician
Category: Motorcycle
Satisfied Customers: 12661
Experience:  25+ yrs. experience
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1986 susuki savage,backfiring in midrange and full throttle

Customer Question

1986 susuki savage,backfiring in midrange and full throttle gets worse while in neutral When observing plunger from back of carb,not really moving.Diaphragm appears to have no cracks,leaks.trigger coil and coil are new,head was removed and seems satisfactory.Compression is 150.Timing chain is tight and valve timing is rt on.Could diaphragm be stiffer and what are factory jet needle and seats .Have played with jet needle position and seats .above high idle it progressivly backfires and loses power bad
Submitted: 2 years ago.
Category: Motorcycle
Expert:  Louie replied 2 years ago.

Hi and welcome to JustAnswer,

Thank you for the question and your patience. Should you still need assistance for information purposes only...

Initially and if no (major) mods, then:

  • • re-check the sparkplug burn;
  • • if light brown to whitish, then lean (most likely);
  • • ensure integrity/seal of original air box/ air filter (element);
  • • of particular interest would be the coupling between air box and carb mouth;
  • • click HERE to reference carb specs.

Proposed further checks (if have not been done) on the possibility of over/under-voltage, regulator/rectifier and/or stator issue. With a volt/multi-meter, determine the battery voltage when:

  • • ignition OFF and then when ON;
  • • when starting the engine;
  • • engine at idle;
  • • when attempting to rev the engine.

Please post back results / observations of the above once tried.

Customer: replied 2 years ago.
The checks u asked me to do already have been checked. The timing on this savage is controlled by the igniter coil slash cid box. Upon hooking up a timing gun ,the timing does not advance I installed a new cdi box There's a coil ground and 2wires for trigger from stator and a ground. There's another 2 wires. What are they for. If the timing stays base then it would fire late and fire through exhaust and miss at full throttle.
Expert:  Louie replied 2 years ago.

Appreciate the information on "what has been tried"

Though the above was based on the contents of what were posted initially. Of particular concern was "...observing plunger from back of carb..." which lead me to suspect that the air box was not even installed.

Perhaps another member could provide a second opinion / alternate approach to your concern. The question would be re-opened as I would be opting out.

Please do not post back an immediate reply so as not to lock the question back to me.

Still, good luck with the Savage.