Sticky valves?

[earthbound14]

My bike has been a little rough to run in cold weather and has decided it won't start at all when it's really hot. In the cold it seems to take forever to warm up but when it's hot out it will turn over and over but will not ignite.

I replaced the spark plugs and they are a little carbonned up but nothing terrible. When it starts during warm days, it runs just fine. The carbs seem to be in order more or less and my mechanic decided it was the valves.

Unfortunately I live in South Korea and my mechanic doesn't speak English, nor does he do proper test before saying things like "The valves need to be done". Drives me nuts. I had the valves done 4 years ago and had a compression test done on the bike. I assumed I would only need a tune up this year.

Has anyone else experienced sticky valves? How did you diagnose it? What were the symptoms? Did you have problems with the engine turning over but not starting?

[prawny12009]

not stating when hot can be incorrect float hieghts/ pilot mixture settings.

when was the last time the carbs where cleaned and balanced?

[prawny12009]

starter motor brushes on the way out cause high cranking loads which can cause hard starting because the electric ignition can't produce a big enough spark at anything below 10v or so whilst turning the motor over.