Discussion Starter · #1 ·
Newby here. I have an '85 Fourtrax that just won't take throttle. It idles perfectly and revs to a point if I feather the throttle. Seems to run better (not perfect) at 1/2 choke. History: Bought as a no start unit, found the fused harness disconnected under headlight. Fixed. Ran crappy so I cleaned carb (3X) and it is no better. Compression is 110 PSI with throttle wide open. Set valve clearance to .008 per manual still no better. Fuel flowing freely from petcock. Timing mark is lined up with the notch at TDC. When throttle is punched it feels like blowback from carb. This was purchased new by the farmer I got it from. Always garaged, plastics good, no cracks, just used to haul feed. It is really in excellent shape for a 30+ year old ride so I hate to have it useless. I know the compression should be 170 area but would the lower number cause my issue? I did squirt some oil in the cylinder to try to determine if the compression loss was valves or rings. Compression was same wet and dry so I assume valves are the culprit. Tried to provide as much info as I could, I hope it is enough for a guru to help me! Thanks for any help.