All I did was change Air filter and oil + filter..

Dang, don't know what I did to upset her (TE510) exactly but she doesn't want to run now. A few nights ago I changed out the dirty Moose air filter with a brand new pre-oiled replacement and changed the oil&filter. I started it up after the oil change and it ran fine, although it was still warm from an earlier ride. Today I hop on it, crank it with the bypass knob pulled open, as usual when cold, and it runs for 30 secs, gives a slight gasp and dies. Restarting resulted in it running for maybe 5 secs with further attempts not lighting off at all. It pops a little while cranking but won't commit. Battery is fresh and strong, gas is fresh premium. I pulled the plug, which is wet and black with carbon, cleaned and gapped it with the same results.

Think the plug may be bad? Need to get another one to try, my tool kit spare is rusted

1800 miles on ODO, valves checked at approximately 1000 miles. 105 hrs on engine. I don't ride it hard into the high rpms. Pump is priming like normal. No rags left in intake or exhaust. Exhaust outlet is black.

What happened?

i have you checked for spark you didnt mention it.

I'm not in any way an expert so this free advice is probably worth exactly what it cost you, but:

If it runs for a while then dies like that I'd suspect something on the fuel side. For one thing, try running it with the gas cap loosened off to make sure you're not building up a partial vacuum in the tank if your vent is blocked (happened to me once on a road bike when I had a tank bag over the vented gas cap and rain got the padding wet and made a good seal). I'm not sure whether this would be so much of a problem with an EFI bike due to the pump, but it's an easy one to check.

Also I've had starting problems which were due to the water temperature sensor failing. It hadn't failed completely so it didn't bring up a "Fail" message or register in iBeat as an error, it was just reading the wrong temperature which of course made the ECU throw the fuel mixture off. From cold I could only start it with the cold start turned off even on very cold days. iBeat showed that it thought the water was hot even when the engine hadn't been running. My symptoms weren't exactly the same as yours but it might depend on what temperature the sensor is stuck at. I'd certainly try starting it from cold without the cold bypass just to see what happens.

The only thing I can think of directly related to the work you did is if there's something wrong with the air filter; not seated properly or over-oiled?

Good luck with it anyway - I know how frustrating it is as mine's just gone in the shop for the starting problem a second time but this time it also had a corrupt display and the "Fail" message showing. Probably all just dirt/water in a connector and/or the display but it was almost due a full service anyway so they're doing it all at once.

Sounds to me like a bad plug, i bet if you check the spark while the plug is out it is sparking up inside the plug and not at the bottom of the electrode. Cracks in the procelin after a while cause this. With colder weather it takes a bit to get fired up and if you dont have a perfect spark it aint happening.

i've encountered this on 2 bikes and it ended up being the Ready Race brand pre-oiled air filter not letting it start.

get a twin air filter and do a light coat of PJ1 oil

too much oil on the air filter ... like running with the choke on

I'll try a new plug 1st. If that is a no-go, i'll loosen the filter. Had very good luck with these pre-oiled Moose filters in the past. Definitely makes sense, though. Thanks guys.

Twas the Plug!

Acquired a new plug after work today. Kablaaaam! Runs like herself again. Still am thinking it's time to get the iBeat on it and check the valves again. Sure can't hurt. Once again, thanks for all the suggestions!

Old plug---------