Polaris ATV Forum banner

1 - 7 of 7 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter #1
I picked up a scrambler for my son that was in pretty rough shape and I knew it would need some work but now I am stuck. I have replaced the carb, spark plug, fuel filter and put in a fresh battery. I know I have spark and fuel but it just wont fire. I am starting to think I have low compression and will need to rebuild it. Is there a top end rebuild kit that is recommended?
 

·
Registered
Joined
·
5,822 Posts
Check the compression before tearing the engine down - it's a two stroke engine -hold the throttle wide open and crank the engine over - if the compression is below 100 psi, take the top end apart and re-ring or new piston & rings or bore and new piston & rings.

A complete top end kit from Niche with a new cylinder is less than $40 on Ebay HERE - they are Chinese parts, but they are going on a Chinese engine - just check clearances and ring gap prior to assembly and assemble clean & dry (be sure to squirt a few drops of two stroke oil on the main and rod bearings), but put a couple drops of two stroke oil on the cylinder wall and spread it around with your fingers before putting it on the piston.
 

·
Registered
Joined
·
5 Posts
Discussion Starter #3
Checked compression last night and I hit a max of 60. Top end kit is on the way. Hopefully my son will be ripping it around the yard by this weekend.
 

·
Registered
Joined
·
5 Posts
Discussion Starter #4
Well I got the top end rebuilt and got it running but when I gave it gas there was no go. I rebuilt the CVT and the rear axle and still no go. I can hear the motor rev up when I push on the throttle and if I have the rear wheels up off the ground they spin faster with more throttle but won't budge when on the ground. I am at a complete loss at this point. I really don't want to have to take it into the shop but I think that is where I am at.

Any thoughts?
 

·
Registered
Joined
·
5,822 Posts
Describe "rebuilt the CVT" - does that include the variator, driven clutch and a new belt? The 50 can not be expected to pull an adult, and you might be able to hold it by hand without spinning the tires, but it might pull an adult if you kinda push off from a dead stop. They are not power houses. Obviously you didn't get it going by the weekend you were shooting for.
 

·
Registered
Joined
·
5 Posts
Discussion Starter #6
Describe "rebuilt the CVT" - does that include the variator, driven clutch and a new belt? The 50 can not be expected to pull an adult, and you might be able to hold it by hand without spinning the tires, but it might pull an adult if you kinda push off from a dead stop. They are not power houses. Obviously you didn't get it going by the weekend you were shooting for.
Yes, all new polaris parts. it won't even move with me standing next to it pushing the throttle. While i don't expect it to hit top speed with me on it it should be able to move with me on it, I'm only 160lbs. The bike isn't even moving unloaded though.
 

·
Registered
Joined
·
5,822 Posts
You might need to run it with the clutch cover off to observe the operation of the variator. If the rollers were inadvertently installed wrong, it will not work. It's also possible the parts are binding for an unknown reason. It's also possible the problem is in the clutch within the driven clutch. My initial thought is the variator is not closing and pulling the belt into the driven pulley.
 
1 - 7 of 7 Posts
Top