I have a 1987 LT 500r and was wondering how much the power valve should rotate on its axis? 5°, 45°, 90°? I know that at 4500rpm the power-valve should rotate seen though the sight glass on the jug. I have seen virtually no movement. The quad is not sluggish just a little raspy at the top end. This leads me to believe that the power valve has little effect on performance. It doesn’t make sense to me. I would think it would run like crap. Any comments are appreciated. Thanks

 

The power valve should rotate somewhere near 90* closed to wide open. I've got a '87, and an '88 and can usually blip the throttle and see the valves open thru the sightglass. One thing on these is you ocasionally have to pull the jug and clean the valves due to oil/gum build up. I run both my 500's on Maxima 927 and 108 fuel, and it seems to burn cleaner than most of the oils I've tried. If yours is not opening at all, It might be time to pull and clean, good time to re-ring also. Hope this helps.

 

I have an 87 and I was running belray and it was just not running clean enough so I switched to the maxima and it has ran fine since. Also when I bought my quad the previous owner had it rebuilt and it blew up when I got it. The problem that we found out that was wrong was that the exhaust valve has a screw that goes up through the bottom that holds it in place. Well this screw was either never put back in or it fell out. Well good luck