Battery is brand new and tested charged. When attempting to start the bike it has a slow crank which has been an intermittent challenge occuring more frequently. Lights are strong and I even tried bypassing the Clutch switch to remove it from the list.

It sounds like a bad starter. You can have the starter tested at a place such as Auto Zone or Advance Auto, but it needs to be taken off the vehicle.

should not be 15 volts 14v - 14.30v max 15 volts wile running is over charging the battery. and you dont want that as over time the battery over heats and can go bang. check the voltage regulator...

You need to check your charging system, if your stator is bad your battery will not charge. As far as it shutting down while riding that sound like you have an intermittent ground, so check all wire connections.

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bike will not start or stay running on a full charge battery/bought brand new battery, still same promblem,jump bike off,will crank ,ride bike for 30 min. park bike, leave bike...

How long is the bike setting between when you park it and when you try to start it again? When you get ready to ride it, did you put a battery charger on it and bring the battery to a full charge?

When thinking it's getting to be time to ride, I recommend charging the battery with a charger disigned for ATV'S/motorcycles. When the battery is fully charged, take the charger off and test the battery with a load tester. If it passes the load test, attempt to start the bike. If it starts, and there is no further problems, Enjoy the ride till you park it long term again. I might suggest putting a battery tender and very slow trickle chat=rge on during storage

Hope this helps you

if the voltage is too low it may just be engaging the starter solenoid but not spinning the starter itself. which would make a clunk noise.

sounds like the problem is your battery is not charging when you are riding. The most common cause is a faulty regulator / rectifier. Contact a motorcycle wreckers for these parts, or your yamaha dealer.
Easy way to test is, when your bike is running, and the lights start to dim, before the bike shuts down, using a volt meter, test the voltage at the battery terminals, should be about 14V. If faulty rectifier,no charge going in to your battery, then the reading will be low, about only a few volts. If you dont have a volt meter, then any mechanic shop can do this test for you. best to have this done before buying any parts.

Sounds like the oil is thick. Do you know what weight oil was installed last? If there was 40 weight put in and its getting colder out it get thicker. You can change the oil to a 30 weight and change the filter to see if that helps.

I can think of 2 possibles,it could be a bad battery cable or an intermitent short in the starter solenoid, check or have the battery cables and there connections on both ends first not only are they a cheaper fix but the problem you describe sounds like a current flow issue.Test them with or have them tested with an ohmmeter they should show o ohms resistance,and while not attributed to the problem I do not reccomend using Bosch spark plugs of any variety,the best plugs for any Japanese vehicle are NGK's,this comes from my personal experience with them and other techs that I have worked with.

Don't rely on on whether the bike will start at a gas station to determine if the charging system is working. Get the multimeter out and do a proper test. Should be getting about 14.5 volts @ around 3K RPM. It's too easy of a test to to just skip. If it is charging then start looking for something else. Was the new battery properly charged to begin with? Loose battery connection? I suppose the GPS could be too much but you said that it was dying last november, so I would suspect something else. P.S. you need a properly charged battery to get an accurate reading for the charging test.