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Hey Guys. I'm pretty new to this Forum, never posted any threads yet but frequently visit to figure out issues on my atv. I have a 2011 Sportman 850XP EPS with 80hrs on it and my issue is when I start to accelerate from a standstill, it almost feels like the back wheels spin. Its hard to explain but i just noticed this recently. It sort of jerks 2-3 times before it takes off. Would this be an issue with the drive belt?

Also, my handbrake pumps very frequently without actually engaging the brakes. I press the brake and it goes all the way in without applying any pressure. When I try it again, it works fine. Ive noticed this is more frequent when i have the wheels turned. Any suggestions?

- Chris
 

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Sounds like you have flat spotted your belt. In simple terms, the clutch will slip on the flat spot until the rpm's are high enough for the clutch to grab the belt tight enough that it won't slip anymore. Don't have an answer for your brake issue.
 

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Also, my handbrake pumps very frequently without actually engaging the brakes. I press the brake and it goes all the way in without applying any pressure. When I try it again, it works fine. Ive noticed this is more frequent when i have the wheels turned. Any suggestions?

- Chris
99% of the time no brakes then pump and have brakes like you described is a bent brake rotor.
 

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first the simple things
air in the brake lines have them bleed
and yes probably have a bad spot in the belt
 

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Discussion Starter #6
Hey guys thanks for the response. I've bled the brakes and this did not resolve the problem. Would this have anything to do with bad brake pads? I def need to replace them. It seems mostly like the brake is not pumping when I have to wheel turned left. The brake rotors seem fine.
 

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If one rotor is warped it will force that caliper to open farther than it should which will take a pump of the handle to make up the space before it touches the rotor. If your pads are shot I would replace them too. But it's not likely the problem.
 

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Hey guys. I looked at the belt, it seemed ok from front and back. Im going to take it off totally this weekend when i get a chance. Any other thoughts of what it could be besides belt? I was changing my brakes and rotors today and the front wheel hub was cracked when I took it off. Not sure if it broke when i was taking the rotor bolt off or it has been cracked. I though this might be it too. But ill take a look when I put the new hub on.
 

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Hey Guys. I'm pretty new to this Forum, never posted any threads yet but frequently visit to figure out issues on my atv. I have a 2011 Sportman 850XP EPS with 80hrs on it and my issue is when I start to accelerate from a standstill, it almost feels like the back wheels spin. Its hard to explain but i just noticed this recently. It sort of jerks 2-3 times before it takes off. Would this be an issue with the drive belt?

Also, my handbrake pumps very frequently without actually engaging the brakes. I press the brake and it goes all the way in without applying any pressure. When I try it again, it works fine. Ive noticed this is more frequent when i have the wheels turned. Any suggestions?

- Chris
Seems like you're already working out the brake issue.

As for the belt, what kind of terrain are you riding it in? If you're going up a steep hill you should be using low gear. If you're going under 10mph for extend periods you should be low gear as well. Not running the proper gear will put the CVT system into a range where the motor is not spinning the primary fast enough to force the weights to pinch the belt tight enough.

That leads to the clutch "slipping" on the side of the belt, creating flat spots as you partially described feeling as jerkiness. The slipping ALSO creates lots and lots of heat that will glaze the face of the belt that contacts the face of the clutch sheaves, which will give you that feeling that the wheels are just spinning yet they aren't and you're not moving.

In simple break down, the primary (smaller clutch) spins faster and faster forcing the weights outward to pinch the belt. While in the secondary the belt has to be pulled tighter and tighter to force the secondary to open and thus giving you less torque multiplication and a better ratio for high speed riding. So if the side of the belt has been glazed (looks very shiny) then it makes the CVT work even harder to gain enough friction between the belt face and secondary sheave face. IE you have to have higher RPMs in order to get it to do the same amount of work at the low end of the range and at the top end.

Attached is an example pic with the dull black one as a new belt and the shiny one as the old stock one I took off after running about 500 miles with bigger, more aggressive tires and not clutched properly for it.

While you have the CVT cover off, have the rear jacked up, remove both rear tires, chock the front tires, ensure you have it in 4x2, set it in park. Slowly advance the throttle and see if you can visibly see is something going wrong.
 

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I had a hub crack to where the splined part breaks off the rest of the hub from my awd engageing when rear tires were spinning fast from a dirty plug at the 4x4 adc switch and when it cracks it allows the rotor on the outside of the hub to wobble in the caliper witch would cause your jerkyness and haveting to pump the breaks mine also happened the the front right (speedo sensor) causeing my speedo to go crazy .....replaced hub and brake pads all problems fixed...,hopefully this helps
 
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