This isn't a new topic but I'm not seeing any other posts with similar issues: I've been rebuilding my 2002 YZ 426 over the last few months and, until lately, it's been running great. Over the last few weeks, however, it's been starting on the 1st kick, running for maybe a minute and then slowly dying. It will start again after a few more kicks then dies again until eventually it just won't start at all. (Yesterday, however, it ran all day with absolutely no problems?!). Today the same symptoms appeared again. I've checked spark, replaced spark plug, performed leak down test and installed an inline fuel filter. I've also (today) drained the float bowl and replaced the pilot jet. The valves and timing are in spec and engine oil and air filter are both good. Any ideas?