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· Registered
5 Posts
Discussion Starter · #1 ·
Hi guys. New here and Polaris driver for 2 years now.
Bought a used Predator 500 from 1st owner, 2005 with first tires on it.

Driven for 2 years - approx. 200h and 15-20 oil changes - flawlessly.
Approx. 2 weeks ago while shifting to 4th lost the gear, a little rattling for few seconds in that gear - but no changes whatsoever on power or other gears.
As I was 8km from home decided to drive home - used all gears except 4th (5th worked fine).

Got home and knew I would have to tear it apart.
Drained oil and found some metal filings inside. :sad
Torn the engine almost apart - got to the cylinder and piston with some visible damage.
Waiting for tools to arrive (magnet puller) taken the pictures available HERE

First I'll need your opinion on the state of the piston + cylinder - should I replace both? FYI, the cylinder is only visibly scratched, while the piston skirt has some damage that can be felt with "fingernail" test.
Secondly I'll need further info with the gearbox as soon I get there.
Third - I got to the clutch basket, but unable to unscrew the screw - any tips?
Forth - what do you suggest, any other mods or renewals at this point?

I'll get back with info and pics as soon as I get into it.

BR, Kenny

· RIP 3/16/20
3,999 Posts
I am not a predator expert, but I do know engines. I would take the piston and cylinder to a machine shop to have it measured. Unless you have that knowledge and the right tools. The is really the only way to know if you need to have it bored oversize or replaced. The cylinder can get out of round and barrel shaped from top to bottom with use so the measurements have to be done in certain places in the cylinder.

I haven't looked at the photos, but my feeling is that as long as you have it torn down, might as well go all the way and get it done right. That way you know it will last as long as you do.

· Registered
5 Posts
Discussion Starter · #4 ·
Decided to replace piston and cylinder. Still in the process of disassembly of the "gearbox".
I'm having troubles getting the clutch basket of (I simply cannot unscrew it). Will have to fix the engine from moving and then try harder. ;)

Meanwhile I "lost" one part - basically I found the part by disassembling but have no idea where it belongs to. I've added the pics to the gDrive in my first post.
Any idea? I think its from the decompression cam, but how did it get out and how to check and insert back - as far as I know the decompression cam is not serviceable.
Look at the attachment bellow.

THX, BR, Kenny


· Administrator
20,553 Posts
Since I do not have the parts in hand, I'm guessing it is from the decompressor as you seem to indicate you think it is from - if it is from the decompressor and you have the tools and expertise, you might disassemble the cam and reinstall the part. If you fail, you will still be buying a new cam.

Where did you find the part? Are you sure it is not a locating dowel from the cam hold down or a roller out of a bearing?

· Registered
5 Posts
Discussion Starter · #8 ·
Hey guys. My engine is finally rebuilt.

Got a spare tranny, changed and put together a month ago.

Already had a 10h maintenance. No issues except the clutch working at the very end - the oposite of a worn clutch. Set the screw to max, still barely working. Like the push rod would be shorter or something like that.

Ordered a new shaft - first diagnose is a worn or somehow damaged shaft.
Otherwise proud to have succeded and driving around with a smile.

Oh! The misterious pin was the pin from the shift drum - neutral indicator pin for the switch on the left side.

Thx to all!
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