99 DT150 intermittent starting problem????

[stevenbeaudet]

Have a 99 Suzuki DT150 that fires up and runs great after it's been sitting a week or longer. Problem is when I take it out and run a couple hours. Sit 3-4 hrs it doesn't want to start. Just turns over. Replaced plugs, gear counter coil, ignition timing coil. Took it out yesterday after they told me this fixed it and same problem. Pulled the first plug wire off and checked spark with an extra plug and it fired up on second bump while looking for a spark. Put plug wire back on and fired up every time after. Made it back to the ramp. This problem started last summer and got worse. Just got it back after having a horrible time locating parts and it's still not right. Please help! Any suggestions would be greatly appreciated. Also when it sits while we're out the motor is trimmed up. Bulb holds pressure throughout the day while it's sitting. Thanks.