Polaris ATV Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
23 Posts
Discussion Starter #1
So I picked up an 04 sportsman 90 that was blown up. Previous owner didn’t have oil line hooked up n toasted piston, jug and rings. I put new top end on it. Has great compression. Bled the oil pump, machine fires up runs great for little while then it’s almost like it locks up or loses power because the machine just dies. If you go to kick it over right away it’s solid but after a minute it fires again but runs rough then dies. Let it sit and the cycle continues. To me it almost seems like the electric dies and motor vapor locks. I did notice when it sits fuel leaks out of over flow. Going to pull carb and clean tomorrow but didn’t know if these machines have the electric throttle cut off or what else I should look for.
 

·
Registered
Joined
·
8,562 Posts
Yes - it has a throttle switch - should be open when released

Dying and being solid (locked up) is not good - I would remove the cylinder to check for scoring or another possible problem
 

·
Registered
Joined
·
5 Posts
Just FYI, I was fixing up a 04' 90 Sportsman a couple of weeks ago. Carb kept overflowing and so I needed to rebuild it. I went online to get the kit and opted for a $14 aftermarket carb from Amazon. Works perfectly.

Sometimes it's just easier to get a new carb rather than try to fix an old one up.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #4
So just got back to working on this machine. Pulled head off again and piston and cylinder look great. No issues there. Pulled carb and tore it down and rebuilt it. Question I have now is air fuel screw was only backed out 75% of a turn.. almost every machine I’ve worked on it was anywhere from 1 1/2 to 2 1/2 turns out. What should this on be? Haven’t tried to start it yet since tore it back apart
 

·
Registered
Joined
·
192 Posts
One thoughtI had, is did you gap the piston rings before installing them? If not, they could be too tight causing it to seize.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #7
I fired it up but it seems like it’s not getting oil. I primed oil pump but no matter what it’s running real lean. If I switch to pre mix what would be a good ratio?
 

·
Registered
Joined
·
23 Posts
Discussion Starter #8
One thoughtI had, is did you gap the piston rings before installing them? If not, they could be too tight causing it to seize.
Oh shit I’m a bone head... nope I didn’t. I rushed and threw it together. I bet you’re right. It gets hot and expands and shuts it down. Looks like I’m pulling jug off
 

·
Registered
Joined
·
23 Posts
Discussion Starter #9
Pulled it apart and everything looks good and new thank god. Anyone know what gap should be set at?
 

·
Registered
Joined
·
8,562 Posts
Nominal end gap is about .012 - the service manual does not spec the end gap other than the service limit.
140146

If the gap exceeds .030, install new rings
 
1 - 11 of 11 Posts
Top