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drummerdave

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Reply with quote  #1 
Hi Guys. 
I just bought a bit of a fixer-upper 2004 Predator 500.
It is actually a pretty clean machine, except for the ugly plastidipped plastics, horribly worn out chain (equipped with missing teeth on both sprockets).
The biggest issue is it has a top end knock throughout the rev range.  It does it at all rpms when cold, and when it warms up it stops at idle after a few seconds (like it settles down), and starts again as soon as I touch the throttle in the least.  

It does start super easy - the moment you hit the starter in fact, so I dont think it's a case of tight valves.
Seems to run well with good power.

I suspected it might be a stretched cam chain or bad tensioner. 
I pulled off the exhaust and the cam chain tensioner.  It works correctly, so it's not the tensioner.
I read on one of these forums that if you can put the tensioner back in without backing it off, your cam chain is stretched.   I was not able.  I dont recall exactly, but IIRC I'd say the chain held it out between 3/8" and 1/2".    Is that a valid test, or is there a better way to tell if it's stretched without taking it out and measuring between the pins?  
Next I plan to take the tank and valve cover off and see if anything looks amiss in there, but aside from pushing on the valve springs to make sure none are broken, and checking the valve clearance, and looking down the spark plug holes to see if it looks ok inside the combustion chamber, is there anything else I can check?
Are any of you familiar with what will cause those symptoms?


Everybody likes videos.  Here you go.   The knock doesnt stand out as much in the video as in person, but you can hear it. 
Predator 500 Top End Knock


Oh, and as an aside, I bought a cheap chinese ebay chain and sprocket set for it.
The rear sprocket doesnt want to fit on the carrier, like the sprocket was made just a little too small.  Should I assume that is a result of it being a cheap chinese ebay chain and sprocket set, or is there some trick to putting those on that Im missing?


Thanks!


redpred

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Reply with quote  #2 
YEAH I WOULDNT RUN THAT UNTIL YOUR RE-SHIM THE VALVES AND CHANGE THE CAM CHAIN.... BUT LOOKS LIKE YOUR ON IT! 

CHEAP CHINESE SPROCKET LOL [fighting0010]

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Kmack

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Reply with quote  #3 
Hard to tell from the video sound but if it is pretty worn, and if someone let the chain and sprocket get like that you can assume it was rode hard and put up wet, so somewhat abused and neglected. The noise could be piston slap or a loose wrist pin. Does it sound like it's coming more from the top end or bottom end?
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drummerdave

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Reply with quote  #4 
It definitely sounds like it's coming from the top end.

I think the last owner abused it, where the previous did not.   It's clearly been greased and things like brake pads kept up with.  

Is there a way to tell if it's piston slap/wrist pin issues without tearing down the top end?

Any thoughts on my "test" on cam chain tightness?    Should I just spend the $50 and put a new one on it regardless?


Kmack

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Reply with quote  #5 
If unknown, and with the bad upkeep on other items like the chain and sprockets, it would be a good idea to change that cam chain. if it were to break it would likely cause a lot of damage. run a compression check, if the cylinder is worn bad enough for piston slap you might have lower compression. this will not tell you for sure if is piston slap or a wrist pin but give you more info to decide whether to pull the top end, but likely you be going there anyway. Especially if you're gonna do the cam chain, its not that much more work from there. And the good thing is, then you'll know what you got, no more guessing.
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From: Artesia, New Mexico

BE POSITIVE - Because, if you think you CAN or if you think you CAN'T, you are right!

2009 Outlaw 525 S
2008 KTM 525
2004 KTM 525 EXC Dual Purpose Bike
1998 Yamaha 600 Grizzly - Elk Hauler
redpred

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Reply with quote  #6 
"CHAIN"     ID REPLACE THE CHAIN... SPARE NO POSSIBILITIES 50 BUCKS NOW CAN SAVE HUNDREDS LATER
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gen3usa

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Reply with quote  #7 
more then likely the valves need adjusting, pretty bad too! it as well as the chain....
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drummerdave

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Reply with quote  #8 
Compression tester on order. . . 
I think I might go ahead and order a cam chain too, but Im debating if I should wait until I pull it apart or if I should risk placing 2 orders and double the shipping costs if I need additional parts.
drummerdave

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Reply with quote  #9 
I still have no real info on the cause yet, but I did find a video on youtube of a Predator that had the same noise (except theirs didnt stop like mine did.  Their idle did sound higher than mine which could explain that.)  Of course the poster never commented on the several people's questions of what the cause of noise was because they had the same.
But one commenter did say that they had the same issue with theirs and it was the compression relief valve. 
Im just adding that info here for posterity.  I'll check that once I tear into it to see if it appears to be operating correctly.
fastkill

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Reply with quote  #10 
where you ever able to find out where that noise is coming from? my 04 is doing the same thing.  

Anyone thing that could be the cam decompression mechanism?
drummerdave

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Reply with quote  #11 
Not yet. 
I've got a new cam chain for it, but havent had time to tear into it and see what's up.

Bad timing really... I just bought a house, and we have to remodel it before we move in, which means pretty much every minute of my spare time is being spent over there working on the house and not my Predator.

But if you figure yours out before I get a chance to, could you post up in this thread to help out the rest of us with this noise?
drummerdave

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Reply with quote  #12 
Hey guys,
I finally got a chance to open the top of my Predator up and see if I could find the source of my knock.

I will say I did NOT get to check the valves.  I falsely assumed by buddy would have a feeler gauge. 

But, physical inspection shows my decomp cam is flopping around all over the place, and everything else looks perfect.



Looking inside the hole on the side, there doesnt appear to be a spring in there at all.

So Im about 90% sure that's my issue.  Would you agree?
Team Bricktucky

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Reply with quote  #13 
no I would not 100 % agree , my 560 pred has very old web cams and the decompressor is just as sloppy as yours . it isn't making any noises . Id check the valve lash , replace the cam chain and check for the sound again. when checking the lash check the valve springs , see of any are real easy to push down. it could be a sign of a broken spring. you also may not have any issue other then the valve lash on that exhaust valve, it maybe out of spec. anytime I had a ticking coming from that decompressor the valve lash was off , TOO LOOSE. if the noise you have is more of a rattle sound it could be a start of a sloppy piston or rod bearing, but id say the chain is loose ,the lash is out of spec and the tensioner isn't set right or wore out... I really need to hear you engine in person to really know. if you have a bore scope camera look inside the cylinder , see if the valves are seated and check the cylinder walls for piston slap scraping

then again who knows you could be right, guess it could be that sloppy lobe. I just feel its a chain issue or valve train, springs , valves or tensioner
drummerdave

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Reply with quote  #14 
Thanks for replying Bricktucky.

Ill tear it down this winter and replace the cam chain and adjust the valves.   I'll probably ride it a couple times before then.
I will say, now that I have the (drive)chain replaced, the thing pulls HARD. 
It definitely doesnt feel like it's got low compression. 

It's interesting you're thinking a loose exhaust valve.  That's pretty uncommon isnt it?
If it were a broken spring, that would cause that condition Im guessing?


Oh, and I finally got all the plastidip off the plastics.  They're actually in really good condition.  It looks 100x better already.
Team Bricktucky

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Reply with quote  #15 
I had a broken valve spring afew times, every time if happened the engine ran fine but had a rattle tick up top. the predator valve springs are a two spring set(one inside another) the inner spring can break and your valve may still stay in spec but have very little tension. this can be found out by pushing down on your valve buckets under the cam lubes. if you can push one down very easy , that is the one with a broken or wore out spring. im not saying that is your issue for sure but worth a check. heads aren't cheap. also a valve can get hung up with crud carbon, which can cause the valve lash to be loose or cause the valve to be kissing the piston. valves smacking the piston happens a lot with these predators . that's why its important to check the valve train in spec. if you can get ahold of a bore scope camera , stick in the spark plug hole and check for piston contact or hanging valves.
drummerdave

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Reply with quote  #16 
On another note, I've been riding it a little, and have a few things Im wondering about.

The gas in this thing is old, and it was killing out at idle sometimes.  Im guessing it was the old gas causing this, because I know it was at least 3 months old, if not older.
So I turned the idle up a bit and put some new gas in.

Now, after riding it a bit over the last few days (10-15 mins total), I've noticed it's acting a little weird.
If I quickly hit the throttle (in Neutral), the rpms will jump, as expected.   But the revs will hang for a couple seconds before coming back down to idle.
Its been a while, but I seem to recall that means it's running rich, or running lean, one or the other.

I did take the baffle out of the stock exhaust, so it makes me lean toward lean, but the plug looked rich when we had it apart the other weekend.

Any ideas? 
Team Bricktucky

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Reply with quote  #17 
I bet the cv carb slide is hanging up. those slides are prone to getting dirty . id check and clean the slide . its under the gold cap on the top of the carb. I bet there is dirt up there or gunk.
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