I have an 98 savage with 9k miles. The bike runs and sounds great, but it has an intermittent problem of instantly dying. It can happen at full throttle or at idle. If I play with the fuel value and/or choke (Im not sure if this actually helps), it will eventually start and runs for either hours or minutes before it happens again. The previous owner installed an inline fuel filter which is typically half full. When the engine quits, its bone dry. Any suggestions?

Yes based on what you said so far, the inline fuel filter is bone dry, Your correct in the fact your not getting gas.  

to test:

remove fuel line from the petc0ck, grab an old coffee cup or container for gas, turn your petc0ck to prime and see if gas comes out the tank

I would only try this when you see the inline fuel filter is empty, cus if it happens to be working when you test it you will get a little messy and mis-leading results

If you get no gas on the test then your culprit is the petc0ck, try removing and cleaning it out as rust and other debris can clog the filter screen on the petc0ck. If cleaning doesnt fix that replace it with a raptor everone talks about.

HTH

Thanks for the advice. Does anyone know the specific part name and number for the Raptor replacement?

Also, I recently spoke to a mechanic who suggested that the gas gap could be causing the problem by not letting the tank pressurize. Sound reasonable?

Yup,... like Routy says,... could be that too....

This is the Raptor part no.  5LP-24500-01-00
2003 Yamaha Raptor 660 YFM660R
http://www.ronayers.com/browseparts.cfm?SearchString=5LP-24500-01-00&adv=5&kw...