Melted vent line question

So I have been doing battle with my 04 TC450 now for a week. She would not start one day last week so I immediately thought valve play check time. So I did the valve checks and found the exhaust valves seemed a bit tight (could not quite get the .008" feeler in there). Changed shims now three times and am back to original shims. After some head scratching and brain straining, I looked elswhere for problems. A quick visual inspection revealed one of the carb vent lines had somehow rubbed up against the exhaust pipe and completely melted. Here are the start/running symptoms I have.
She will not start normally (no choke).
If I choke her, she'll start but only idle with no throttle
As soon as I twist, she'll cough and flame out.
If I start her with choke and then cut the choke, she'll just die out instantly.
Could the carb have sucked up some melted hose spooge and gummed up the carb ?
Help please
signed
chief head-scratcher
Jerry

Clogged up carb vents will make 'em hard to start. Are you sure the one that melted is now open to atmosphere and there's not a melted glob internal? We just had a similar incident at a mud-fest MX race where most of the vents became partially or completely stopped up with mud. The bike became very hard to start hot or even when it cooled down. When I cleaned out the vent tubes.... bingo! Your symptoms also sound a lot like a clogged pilot jet as well.

Check to see if the vent on the gas cap is clogged.

Thank you Columbia510, you called it. It was the fuel cap !