my buddies xplor was running fine, then all the sudden there was a nocking sound inside the engine so we shut it off, it will start right up, but still makes this god awful clunking noise, i am going to look at it tomorrow and take it for a spin to see whats wrong any suggestions? broken ring, burnt piston, smashed skirt, i have rebuilt 2 and 4 strokes, do you think i sould pull the jug, and look at the cyclinder, and the rod to see if there is scoreing or looseness.

 

can anyone think why this thing is doing this?

 

If it is still running good take the clutch cover off and check the buttons in the primary clutch efore taking the motor apart.Had a knock in one of mine one time and it turned out to be the clutch was wore.

 

thanks, i am going to just pull the bike in my shop, and start eliminateing problems, it is not the belt, could it be a bad helix or clutch weights, and then if the tranny is not at fault then there goes the motor, one more thing the thing makes this noise when the tranny is in neutral, do the polaris belts spin when revved in neutral?

 

Sounding more like a bad primary clutch.The slide buttons and bushings.But if its not that it could be piston slap.Time for topend.

 

would the thing do anything when driving it such as skip(the tranny), or anything else? someone else said it could be the wristpin slaping around in the motor, he replaced it, and the noise went away, oh well guess i will just pull the tranny cover, and then the top no big deal.

 

There are two "transmissions" on these things. The cvt with the primary and secondary clutches connected by the belt. Then there is the actual gearbox with forward, neutral, reverse and low if you've got it. The cvt does indeed spin when the "tranny" is in neutral. Take the belt off and run it. That eliminates everything except the motor and primary clutch. Go from there.

 

thanks guys

 

fixed the problem, it happened to be the headpipe, was not sitting against the engine, i do tho have to replace the belt, because it is slipping really bad, already know how to do this, done pleaty of sportsmans to last a lifetime [img]i/expressions/face-icon-small-smile.gif[/img]

 

Glad to hear that it was some thing simple and CHEAP to fix.