so recently i purchased old blue a 96 polaris magnum 4x4 425 ran ok not so great at full throtle but for 750 bucks i wasnt gonna complain took it home decided me being a genius would clean the carb and do a tune up changed the spark plug the whole 9 yards well when i was trying to get the carb out the choke cable guide broke so i had to order a new one wound up buying a new seat and valve just to be safe so i get the parts put everything back together and back apart and back together and ........... you get the point i have went through this thing a million times it seems checked float level made sure inlet valve was not stuck open or closed made sure choke was opperating correctly 2 new spark plugs an oil change a gearcase oil change and about 2 hundred dollars worth of nuts a bolts later my atv runs like crap horrible knocking sound when throttle engaged at any speed but idle it idles like a champ lol couple of strange things idle adjustment screw makes no difference in rpm at all strange i know as far as i can tell im getting spark gap is good it will run at idle but just doesnt want to stay running for very long on top of this the starter switch was already bad because you have to wiggle it back and forth between off and on to get it to start so i changed the bushings in the starter case (what the previous owner said the problem was with the starter) and no luck still have to wiggle it just a little less now. the knocking is awful it is a real low deep knock and is slow in speed to me it sounds like the piston smacking but im not a mechanic as im sure you have probably figured out by reading this post lol any help at all would be greatly appreciated!

 

wow man that sucks

If your idle screw inst doing anything, id think the carb is toast somehow

maybe somthing to do with valves, timing, or cam?

blown head gasket?

spun bearing?

 

i thought maybe a head gasket too but with it running i sprayed carb cleaner around the seal to see if there were any leaks you know listening for rev ups or downs and nothin thanks for the post though. i dont think its too serious like a cam only because before cleaning the carb the quad ran fine it just was a little slow at wot.

 

wrong sparks plug..too long hitting the piston?

 

tried that one too made sure it was correct spark plug and gap. thanks though for the post .

 

I think you need to adjust your valves.

 

would thats just start though after cleaning the carb? no to familiar with valve adjustments on 4 strokes ....

 

It shouldn't have just started then unless it's a coincidence. But the valves will tighten up over time and cause problems. They can even break if they aren't adjusted, but I don't know how to do it.

 

Is there a new type of 2 stroke that I've never heard of that uses cams and adjustable valves? lol

 

its a 4 stroke luda