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Couple questions. I recently bought a 1989 lt 500 quadzilla for 1700$. Thinking it was a good deal I jumped at it, I've always wanted one. I got it home and for the past two days I took it out 4 times. The last time i took it out, I had it driving along and all of a sudden it just quit. Looking around a little bit I noticed that there was coolant resting on the backside of the motor. Not thinking anything of it I went and started to kick it over. And I noticed that it has slightly less compression than it did before. Granted when I bought it it didn't feel like it had that much compression to start with. Is it suppose to be like trying to kick down a wall to start it or is it possible to turn it over by hand?
Any answers or pointers to shoot me in the right direction are greatly appreciated.
 

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2 stroke thinker
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I am far from a LT500 guru but it seems like a blown headgasket or there might be an issue with the rear mounting (rear ears of the cylinder) mounts being cracked or broken. Common issue with the LT500's
You said that there was coolant leaking. ?? Also check the waterpump weep hole.
The coolant leak is a sign of your problem.
If you have access to a cooling system pressure tester to hook up to the radiator, then that may help you.
Hafta start with the basics before you dive into something that may not be the issue.
Rule of thumb.. (K.I.S.S)..."keep it simple stupid" !
 

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A stock 500 in decent running condition should have around 190 psi from a compression test.
Kicking one takes a little effort. You need a heck of an arm to crank it by hand.
It sounds like you have very little compression.
And, as said, possibly a blown head gasket, since the coolant is leaking(could be coming from somewhere else though).
It's also likely that the top end is worn out and needs a rebuild, since you said it didn't have much compression to start with.
 

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^^^^^ WRONG
A STOCK (HEAD AND CYLINDER) 500 should be about 150-160 psi on a comp tester.
 

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2 stroke thinker
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I agree with Carl...190 p.s.I. sounds extremely high...especially for a stock motor.

If you can hand crank that motor, there's definitely a compression issue. but...figure out where the coolant is leaking from.

That is the first issue that I'd be looking at..Head gasket ? If it's blown, that could be your compression issue with the coolant leak .
 

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I'm with mgty. Try locating where exactly the coolant is coming from, although it wouldn't hurt to do a compression test.
 

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I'm not arguing(or claiming to know), only stating that 180 to 190 psi were the only specs for a compression test that I could find.
I also found them on the old Quadracer site a couple years ago, and wrote them down. As I was searching then for curiosity, because no where is it listed in the factory service manual(I have one of those).
I looked and found that the corrected compression ratio is just over 6 to 1, so yeah, 180 to 190 does sound high.
 

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Yes, super high since 150psi is close to 10-1 corrected. 10-1 corrected is a good pressure for pump gas.
It’s good to hear all of the input & enthusiasm from you new folks.
190 psi is 12.9-1, kinda high unless you’re looking for excess detonation. A good way to burn a hole in the piston.
 
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