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Discussion Starter · #1 ·
Ok got a 300 gave to me and didn’t have spark replaced the stator, cdi, pick up, regulator, and coil. Also has a new battery. Kick started ran great. I got a new starter put it in cranked real slow, then the solenoid stuck. Hurried and unhooked battery. Disconnected the starter and now I have zero spark??? Yes the ground is hooked up. It is the way it ran before I replaced the starter. But no spark at all!!!
 

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The ignition system is DC - it has to have over 9.5 volts from the battery to start

Here's the diagram and the trouble shooting guide from the service manual - let me know if this helps

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Would a sticky solenoid cause something to go bad to loose spark though?
Only if it's battery voltage related

Here's what can and does happen: a new battery is installed that is not properly activated when filled with electrolyte or is was activated and set for more than 30 days without being recharged - the charge decays with time and if the voltage is low (below 11.5 volts is considered dead) when the starter is used, the current draw of the starter motor increases as the voltage is lowered - now the starter motor draws upwards of 20 amps at 13.2 volts (voltage of a good fully charged battery) - as the starter motor runs, battery voltage drops and current rises.

Since Honda does not publish the wattage of the starter motor, I'll select the arbitrary value of 265 watts based on 13.2 volts and 20 amps to run the motor without a load (not cranking the engine).

The wattage requirement of the starter motor remains somewhat constant, but will change with heat generated by use and the resistance of the windings - the resistance will increase both with age of the winding and heat.

Put the starter motor under load (cranking the engine) and the current requirement rises - so now it needs 30 amps - to get 30 amps through a 265 watt motor, the battery voltage will drop to 8.8 volts - unregulated voltage drops as current increases. In practice, a good 12v battery will drop to appx. 11.5 when cranking the engine and extended cranking might reduce it to 10.5, but removing the load will allow the battery to recover somewhat, but it requires recharging to restore the charge fully.

Now the solenoid needs voltage to close and the contacts in the solenoid are designed for about 45 amps. If the battery is weak 12 volts or less and the starter motor is engaged, the voltage may drop to 10.5 volts - the solenoid may need 10 volts to stay engaged, so at the moment the starter button is pushed, 12v closes the solenoid, the starter motor draws 22 amps of current and the battery voltage drops as the motor runs - the battery voltage drops quickly (depending on the condition of the battery) - at 10.5v, the solenoid is on the verge of opening and the starter motor is now drawing over 25 amps - the starter button is released and as the solenoid tries to break the connection, there is an arc across the contacts welding them together and the starter motor continues to run dropping the battery voltage more and the amperage rises - if the weld across the contacts in the solenoid is weak, hitting the solenoid with a screwdriver may break the weld and the starter motor will quit running. The process may be repeated with subsequent attempts to start.

If the battery is sufficiently discharged, the solenoid may close and as the starter motor draws current, the voltage may drop below pull in voltage of the solenoid in which case the solenoid will open - as soon as the solenoid opens, battery voltage increases enough to close the solenoid and then drops and the solenoid opens and then it closes and the cycle is repeated - this results in what is referred to as the solenoid 'machine gunning'.

With all this described, the CDI needs a minimum of 9.5 volts to produce spark when the unit is new - it doesn't make any difference if the unit is laying on a shelf or being used in a running machine, the components within the unit age and as they age the voltage required to make it function increases. Now lets say the unit needs 10.5v to produce spark and the battery is at 11.5 v - engage the starter motor and the battery voltage drops to 10.2v - the engine will crank fine, but it does not start - sometimes, with the engine running at cranking speed and just as the starter is disengaged, the battery voltage rises and the engine starts - as soon as the engine starts, the charging system starts to work and all is well; except the battery.

What you need to do is put a meter across the battery terminals and check the voltage as the engine is cranking - this will aid in determining what the root problem is and it might be as simple as a poor connection or a battery that is not up to par.
 

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Discussion Starter · #7 ·
Ok I’ll check those later and see what I come up with thank you for the explanation
 
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