Polaris ATV Forum banner

1 - 20 of 61 Posts

·
Registered
Joined
·
72 Posts
Discussion Starter #1
Hey guys i just replaced the camshaft on my 01 scrambler 500 and now it barely cranks over. Timing is set right and valves are set at .006. have any of you had this problem and what was the cause? it cranked over great before changing the camshaft. any help is appreciated. Thanks guys.
 

·
Registered
Joined
·
10 Posts
if it has the auto decompression feature it will have a steel ball bearing looking dude on the cam shaft with a little centrifugal weight and spring on the side and if it is not functioning correctly the ball bearing will not protrude from the cam causing it to NOT decompress the cylinder leaving you with hard turnovers....if it is working correctly the ball bearing will be protruding from the cam about 1/16-1/8” and as soon as the cam picks up speed the rotational force will pull the little weight outward causing the ball bearing to be flush or recessed in the cam no longer decompressing the cylinder
 

·
Registered
Joined
·
72 Posts
Discussion Starter #3
yeah i actually odered one that didnt work and had to reoder another one because of that exact problem. This one is good.
 

·
Registered
Joined
·
10 Posts
The cam can have the decompression ball and all associated part in tact but if the spring is facing the wrong way it will not decompress the cylinder (I ordered one a while back and it came assembled backwards from the manufacturer and caused exactly what you are describing)
 

·
Registered
Joined
·
72 Posts
Discussion Starter #6
So went back in a checked the compression ball on the camshsft and it is good. the ball is all the way out at resting position. one thing i did notice though is that the timing chain is really tight and i actually had a hard time getting the sprocket on the cam even with the tensioner out. is this normal for polaris or could the timing chain be binding?
 

·
Registered
Joined
·
10 Posts
The cam chain guide (not the tensioner side) but the front one just sits in a little cradle behind the stator plate and when you had the cam gear out there would have been enough slack to allow the guide to come out of the cradle causing your symptoms ie. tight chain and hard turnovers....if it falls out of its keeper it ends up between the keeper and crank gear puting extra tension on the chain and extra resistance when turning over
135747
 

·
Registered
Joined
·
72 Posts
Discussion Starter #8
Thanks this would explain it. i will be checking it tonight. Im thinking it has to be something with the timing chain. It seems like a large amount of stress on the camshaft if its that tight without the tensioner on.
 

·
Registered
Joined
·
7,461 Posts
Braaper don is right, but if you have told the complete story, it is not a concern. The guide cannot be removed or dislodged from it's seat unless the head was removed and head removal is not required to replace the cam, but the chain should not be real tight with the tensioner removed either. How easy does the cam rotate with the sprocket removed from the cam?
 

·
Registered
Joined
·
10 Posts
On my sportsman 500 engine it is able to come out of its keeper with the head still on and the cam gear off, it is just not able to come out of the engine....i just recently had this issue
 

·
Registered
Joined
·
7,461 Posts
There is a nub on the upper end of the guide that sets into a notch in the top of the cylinder. The guide cannot be removed or unseated from the lower cradle without removing the cylinder head. It is the same for the Scrambler and Sportsman. If you can move the guide (any more than just perceptible movement) without removing the head, the guide is damaged and should be replaced.
 

·
Registered
Joined
·
72 Posts
Discussion Starter #12
Thanks for the responses guys. i will be looking into this today. im thinking it has something to do with the timing chain. When you guys put on the cam gear was it difficult or should it go right on with the tensioner released?
 

·
Registered
Joined
·
7,461 Posts
There is slack in the chain - gear goes on very easily - then the tensioner device is installed - if I have to roll the engine over and I don't want to install the tensioner, I stick a finger, socket extension or whatever is handy to push the tensioner blade into the chain (the slack is on the back side of the chain and I just want to assure a worn chain does not jump the sprocket), but if the chain has enough slack to jump the teeth on the sprocket, it is worn out and needs to be replaced anyway.
 

·
Registered
Joined
·
72 Posts
Discussion Starter #14
Ok thanks. So im thinking this is my problem. mine is tight even with the tensioner out. in order to get the gear on i actually had to push up on the gear to get it on. mine was very difficult to put on. Ive never had this problem before and this is the first polaris I've done. Shoulve realized there was something wrong.
 

·
Registered
Joined
·
72 Posts
Discussion Starter #15
The cam chain guide (not the tensioner side) but the front one just sits in a little cradle behind the stator plate and when you had the cam gear out there would have been enough slack to allow the guide to come out of the cradle causing your symptoms ie. tight chain and hard turnovers....if it falls out of its keeper it ends up between the keeper and crank gear puting extra tension on the chain and extra resistance when turning over View attachment 135747
 

·
Registered
Joined
·
72 Posts
Discussion Starter #16
  1. hello h
  2. On my sportsman 500 engine it is able to come out of its keeper with the head still on and the cam gear off, it is just not able to come out of the engine....i just recently had this issue
    hello how did you go about getting the guide back in the keeper. Im pretty sure this is whats going on. i cant get the cam gear on the camshaft because theres not enough slack in the chain even with the tensioner out. Thanks.
 

·
Registered
Joined
·
7,461 Posts
You have to remove the cylinder head to get the guide in the cradle - there is a nub on the top end of the guide that sets in notches in the cylinder and the head holds the guide in place.

I'm wondering if the chain is not meshed with the crank sprocket causing it to be tight.

135755
 

·
Registered
Joined
·
72 Posts
Discussion Starter #18
Well im still at it! Im not sure how but i managed to get some play inn the camshaft with the tensioner on but its still not right! Its still cranking really hard and it will break your hand trying to pull start it. ive tried other batterys to see if its the battery and no luck. The only way ive got it to turn over at a descent speed is by jumping the battery with my truck. BUT the truck has to be running or else it will wear my truck battery out too pretty quick. oknce i start the truhck up the battery the bike willb. turn over good. Something is definatly wrong and I'm not sure what. im al.ost to the point that i don't want to turn it over anymore because of the possibility of stretching the timing chain or messing up other things. I was thinking it could be a bad starter but its the same differance when trying to pull start it. I'm thinking its got to have something to do either with the new camshaft or timing/valves but ive triple checked all of it. Sorry for the long story but I'm getting frustrated. All i needed to do was change the camshaft and rockers and it turned into a shit storm!!
 

·
Registered
Joined
·
72 Posts
Discussion Starter #19
Well im still at it! Im not sure how but i managed to get some play in the camshaft chain with the tensioner on but its still not right! Its still cranking really hard and it will break your hand trying to pull start it. ive tried other batterys to see if its the battery and no luck. This thing will drain a fully charged known good battery in a few seconds. The only way ive got it to turn over at a descent speed is by jumping the battery with my truck. BUT the truck has to be running or else it will wear my truck battery out too pretty quick. once i start the truck up the bike will turn over good. Something is definatly wrong and I'm not sure what. im almost to the point that i don't want to turn it over anymore because of the possibility of stretching the timing chain or messing up other things. I was thinking it could be a bad starter but its the same differance when trying to pull start it. I'm thinking its got to have something to do either with the new camshaft or timing/valves but ive triple checked all of it. Sorry for the long story but I'm getting frustrated. All i needed to do was change the camshaft and rockers and it turned into a shit storm!!
 

·
Registered
Joined
·
10 Posts
Late bird is right cause i was having the tight chain and loose chain guide so i pulled the head just now and this is what i found: pic #1 is what i found and pic #2 is how it should be and like he said if it is in properly there is no way to move it
135788
135789
 
1 - 20 of 61 Posts
Top