When to change to synthetic?

VERY ACCURATE

The absolute time to change over to synthetic oil is when your graph of gas mileage reaches a plateau, mesa, table, flat spot and it has effectively leveled off. then you should change over to pure synthetic. If you want to be thrifty, no matter what oil you choose to go with remember that the filter is the object that fills up with all the "stuff" in your oil. IF you were to just change the filter and top the oil off, you would be effectively changing 1/3 of your oil when you do it. IF it makes yo feel good to drain and change the filter both then go ahead. but if the ris a one or th aother then do the filter not the oil...the filter holds all of the contamanents...dust, metal, whatever gets into the engine...
You should, if you are very serious about your bike keep records mileage date, what was done, changed, bought , utneups, spark plugs, oil filters, yo may find that you actually get better fuel economy with differrent fuels, and as funny as it sounds even oils and filters...air filter cleaning and OILING is very important, changing the windscreen on a sport bike to a taller one should result in better fuel economy...tire pressure is VERY important to chnage and find the right pressure for your bike as well...

ACCURATE

IF you are keeping an accurate logbook or record of your bike then the answer is right there in your gas mileage. Not until your mileage has finally reached it's point of where it isn't getting much better. A lot of it would have to do with wear with your break in oil and the temperatures in which you are riding, and whether or not you are putting strains on your bike like hills or if you are on flat land all the time... Keeping a record/logbook is very important...I don't think some people on the FORUM understand how important because they don't even know when they last changed their plugs or cleaned their airfilter and reoiled it...The Maintenance Manual for your bike should be available at beartooth kawasaki, and you should have one...it tells you how to get to things and how to take things apart and put them back together... There is more information in the book than you could get of of the forum in a month of questions...and it is NOT expensive...