I recently bought a 1995 polaris xlt 600 triple with slp pipes and triple air filters. It sat for around 15 years so that give you an idea of what things look like. After cleaning out the gas tank thst the gauge had rusted in and soak cleaned carbs and doing fuel and oil lines I got it running. Put some oil in with the gas and some sea foam to really clean it out. Left the old spark plugs in it as I put a little 2 stroke oil in the cylinders because I knew it woukd take alot of pulling dry. It fired off just the oil then pulled until it ran. It was back firing when let off after higher rmp on the stand so changed out to new plugs. It stopped backfiring now itll rev up to about 3800 rmp and drop down to 1000 and idle then die after about 15 seconds. Adjust the idle screws and took it for a little ride. When given throttle itll run fine but once you let off to idle it dies. Currently has 230 jets in it. Not sure why it does this and if I should change jetting or what.