Trouble starting '93 XT600E
 

I've had my 1st bike for about 2 months, and ~1200 miles. In the last week it's been reluctant to start from cold. Needs a good bit of gas and two or three tries for the engine to catch, starter is cranking fine. Then it needs 15 or so seconds of choke and some revs (presumably get some heat in the system?), or stalls out when I close the choke. Once it's warm it catches easier, idles a little lumpy but ok. I'm worried about the time it won't start when I need it to.

A bit of looking online leads to maybe fuel delivery (filter, carb jet, ??), but it seems to have plenty of power once started...

I'm an absolute rookie as far as troubleshooting a bike. Any simple things to check to save the money of a shop visit?

Sounds a bit lean on the idle(pilot jet) circuit. I'd first clean the carbs good and make sure none of the jets are dirty/partially clogged. If that doesn't cure it going up one size on the pilot jet should help. The fuel mixture screw should also be adjusted, turn it out 1/2 turn and see if it gets better, if it does go another 1/2 to see how it runs throughout. If it keeps getting better that shows the pilot is too small.

When starting you shouldn't use any throttle, it slows down how much fuel gets sucked in the choke and makes it harder to start. The idle may need to be turned up a bit, I keep mine at 1500-1600 mostly, Yamaha technically recommends 1300ish but I feel they start/idle a bit better when cold a little higher.

besides what has been said , check you carb boot also if they have a leak it will lean your mix

++ on carb to head rubbers, thats often the cause (had it on a 43f and a 3tb xt's) of poor starting.

to change them you have to pull the carbs off anyway so get yourself a cheap fuel needle valve and gasket and oring set off flea bay (17 to 21 pounds) and as previous poster advises strip the carbs down and clean them out, use some carb cleaner and give a really good shot of this into every drilling, hole etc and pay particular attention to the jets, the emulsion tubes have many tiny drillings and they all need to be clear. Then put a fuel filter in line from tank to carb to prevent any cr@p getting in from the tank, its a 20 + year old bike and there is sure to be some silt in the tank that could find its way into the jets and drillings and give you problems after you have cleaned it all up.

Good luck

Further explanation of emulsion tube. That is the brass fitting the main jet is screwed into. Just unscrew if from the carb housing. You will notice a row of holes on each side of it. Clean carefully with a needle or pin taking care to NOT making the hole larger. I just push a pin thru and look at the pin for any crud, wipe it off and try again. Lastly I put the pin thru and spin the tube on the pin like an axle. Make sure the bore of the tube is clean, pipe cleaner or something soft will do it.

Clean other jets but take care to NOT make any jet hole larger by forcing something through it. There are rubber o-rings in various places, check their integrity and replace if in doubt. Yes boots can get hard and leak, there are o-rings under the flange where it bolts to the head. A little Yamabond #4 or similar non hardening sealer works wonders there. Same if you have a seeping gas valve on your tank. Put a bit of Yamabond #4 on the o-ring and the surface of the tank and no leak.... Yamabond should air dry for a couple minutes before mating the surfaces. Put a bit on both sides of the surfaces.