P500 Riding with a bad top end?

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Gotduhka

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Nov 25, 2024
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  1. 500
I noticed today the air filter on my 500 has whitness marks from where the PO didn't get the back on all the way. I looked down the intake after the filter and it was a little dusty. Mind you this is with the thing on a trailer to go on a hunting trip in 2 days. I pulled the spark plug and there is oil on the threads but the tip is dry and doesn't have any more carbon build up than a rich mixture might make. I get 100 psi compression which is the max we can read with the decompression valve. I have enough power to never complain and if I am burning oil the cat converter must be taking care of the smoke. My plan is to ride it on my hunts this winter and rebuild the top end in Feb but am curious what other people think about riding it like this for a little while? Also, how common is it for a dusted engine to need a lower rebuild, and will I be able to tell after pulling the cylinder off if I need to go that far with it?

There don't seem to be any walkthroughs on rebuilding these lowers that I can find. What special tools would be needed and how much time should it take a first timer? I have never done a lower rebuild on anything but have done a few Subaru head gaskets and bike top ends. I think if the lower needs anything I might just have to suck it up and pay the dealer because where I live, there aren't really any other options. Very curious what that would cost.

I plan on snorkeling it after the rebuild.

Thanks.
 
906UP

906UP

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Is it running bad? Burning oil? Smoking like a chimney? What makes you think it needs a rebuild? Compression sounds OK. A little dust in the intake track isn't anything to worry about, it happens but these engines are very forgiving. Run it!
 
DRZRon1

DRZRon1

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May 11, 2019
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If it’s running good and doing nothing stupid run it dont worry about it.
Agree, if it runs good, not burning oil - IMO - if it ain’t broke don’t fix it.

I’ve dusted/screwed up many 2/4 stroke top ends - just new liner/nikasil/cylinder/etc. with piston and rings and never even thought about the bottom end.
 
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G

Gotduhka

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Nov 25, 2024
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Colorado
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  1. 500
Thanks everyone. I think it is burning oil, there is oil on the spark plug, it is not enough to cause wet fouling of the contacts however, just wet at the edges and on the threads and you can see deposits caking on the piston from the spark plug hole.

I'm going to run it. The more I use my old mitsubishi tractor the more I realize how crazy anal I have been about my vehicles all of these years.
 

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