Having Starting Issue With my 91 Integra I have replaced the starter 3 times and I still have the no crank issue, I hear the solenoid on the starter actuate then wont crank. Sometimes it cranks sometimes it doesn't usually means bad starter but I have changed it 3 times and the same result after a couple months.

If your 2008 Polaris Trail Boss is not starting from the ignition switch but starts when you jump the solenoid, there are a few possible causes for this issue. Here are some troubleshooting steps you can follow:
1. Check the ignition switch: Even though you mentioned that you installed a new key switch, it's still worth verifying that the ignition switch is functioning correctly. Make sure it is properly connected and that the contacts inside the switch are not worn out or damaged.
2. Inspect the wiring: Examine the wiring harness connected to the ignition switch, solenoid, and starter. Look for any loose, corroded, or damaged wires that could be causing a poor connection or preventing the signal from reaching the solenoid when you turn the key to the "crank" position. Repair or replace any faulty wiring as necessary.
3. Test the solenoid: Even though you mentioned that the machine starts when you jump the solenoid, it's still worth testing the solenoid itself. Using a multimeter, check if the solenoid is receiving power when the key is turned to the "crank" position. If there is no power, the issue could be with the ignition switch, wiring, or a related component.
4. Verify the starter: Ensure that the starter motor is in good working condition. If the solenoid is receiving power, but the starter motor does not engage when you turn the key to the "crank" position, the starter motor itself may be faulty and need to be replaced.
5. Check the battery: A weak or discharged battery can also cause starting issues. Make sure the battery is fully charged and in good condition. Clean the battery terminals and ensure they are securely connected.
If you've followed these steps and are still experiencing difficulties, it may be helpful to consult a professional mechanic or a Polaris dealer who can diagnose and resolve the specific issue with your ATV.

Video below might help

key --ignition switch--solenoid --failure

Eliminate the battery as the issue first up.
Check if you can jump start the car from another vehicle with its engine running or at least have the starter motor kick over the engine. If it starts then you know your battery is the issue. Having lights does not mean the battery has enough cold cranking amps to turn over the starter motor.

2. If the starter cranks the engine over as normal with a jump start from another car but your engine does not start you have also eliminated the starter motor as the issue.

3. If it does not start and the starter motor will not crank the engine over either when you jump start from another vehicle, then there may well be a problem with the starter solenoid, the starter motor itself or with the wiring to the starter solenoid or to the starter motor. No power getting to the starter motor solenoid or to the starter motor and obviously the starter motor will not turn over.

4. So I need not write much more here, there is a very good guide to solving starting issues here which I suggest you might like to read.

No Start Problems

That clicking you hear when try to crank is the starter solenoid. Replace it and roll on.

sounds like you may have a starter relay issue or maybe the starter it self. also did you check any relays that are associated with the ignition? I am going to bet the relay or starter..good luck

Your starter solenoid is likely the cause of your intermittent starting problem.

The solenoid sometimes will develop an issue where it does not engage to allow current draw from the battery by the starter, which causes intermittent starting issues.

If you hear a "click", during the times that the engine will not turn over, this is the most likely culprit. Replacement of the starter will solve the issue.

The starter has always had a solenoid to conduct the correct current to crank. the click you hear from the solenoid activating to close the contact for the starter. However the contacts inside the solenoid are corroded due to arcing after several times of starting. When this happens, there is high resistance through these contacts hence low current to the starter not enough to crank. The solenoid needs to be replaced. If they don't sell a separate solenoid then you have to replace the integrated starter.

Thoroughly check the battery to chassis to engine ground system is properly connected and in good order.
Check/replace any solenoid control relay if fitted -(slave relay interfacing between ignition start sw and starter motor engage solenoid).
Check condition and connections of any fusible link (or in line Maxifuse).

This happened to me on a 95 Integra GSR and the entire starter did not need to be replaced, just the solenoid pieces. They get old and worn down and the plunger no longer makes a good connection with them, hence the "click". Replace the solenoid panels and sand the plunger and your good as new. You can find instructions for this on the net, just do a search for it.

It almost sounds to me like a timing issue. Did you get it timed properly after the distributer was installed? Another thing is the timing chain. Aim a timing light at the crank marks and see if they are staying in the same place, or jumping around. If they are jumping your timing chain may have jumped, or be badly worn, and will need to be replaced.