So does your CDI look like this:



If so (check for 5 pins - not 4), then your ignition system is powered totally off moderately high voltage generated by the stator when the engine is turning. In that case the ignition system doesn't know nor care whether the engine is being turned by a starter motor, or by push starting. The only difference is that push starting may be turning the engine at a faster speed. Obviously faster is better if the engine has problems, and this may explain your results.

You have spark while cranking, and the quad runs fine once it does start up. That exonerates the ignition system. The quad cranks fine. That exonerates the starter motor and battery. There isn't much left as far as electrical stuff goes.

If you have a 4 pin CDI (DC powered ignition) then that raises some more issues (albeit very unlikely long shot ideas...).

As far as timing being affect by the starter button, perhaps you could measure that. Do you have an access screw plug in your side engine cover that allows you to see into the flywheel area (I don't know your engine specifics)? This is there to allow a timing light to shine into the hole and check the timing while the quad is running (or cranking).

 

Yes it does have the 5 pin.
I switched the motor from the m the running one into the not starting one. It ran for half a day now it is doing it again. I am starting to think it has to do with the rectifier wiring. I can unplug the rectifier while it runs and its still runs. the voltage does not increase much when I rev it.
what do think.

 

Rectifier/regulators have one purpose: Keeping your battery charged up when the engine is running. They have nothing to do with spark, spark timing, or keeping an engine running.

They can keep a quad from starting if they cause the battery to eventually go flat, and the starter motor can't turn the engine fast enough to start up. But you have stated this is not the case. Are you *sure* the starter isn't cranking a bit slower on the quad that has now had two engines in it? One sure way to tell is to use jumper cables to your car. If your quad battery is partially discharged the car battery will prop it up enough to eliminate that possiblility.

Your charging system should put out 13.5 to 14.5 volts on the quad battery terminals with the engine running at medium fast speed with the headlights off. If it isn't doing that then you have a battery charging problem - but again I need to emphasize that this has *nothing* to do with your quad not starting as long as your battery is fully charged (or jumped to your car battery).

So out of curiousity has your first non-starting engine been installed in you other working quad?

 

It is better now. It will start after it has been running.
I still have to jump it or push start it at the start of the day but after that it is good.
The engine do overheat tho when worked hard.