2009 Zx6r low compression - ZX6R Forum
 
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post #1 of 8 Old 12-14-2019, 09:41 AM Thread Starter
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I have a 2009 zx6r that sat for at least 3-4 years I just took off the head and lapped all the valves replaced the springs, oil seals and shims, after that I cleaned up the top of the pistons and looked at the cylinders and they had beautiful crosshatching without any scoring so I didn’t bother splitting the case to check pistons or the rings “ big mistake lazy ass”
Then I put the engine back together and it wouldn’t start up so I ordered a compression tester that would fit it and these were the readings Cyl #1 70, #2 150 #3 70 #4 90, and with oil they all go up to 200 psi

Last edited by Bryan12x; 12-14-2019 at 12:44 PM.
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post #2 of 8 Old 12-14-2019, 12:17 PM
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Squirt a little engine oil into the cylinders and try again. If the numbers go up, rings are bad. If they stay just as bad, something in the top end is still wrong....

"Basic stuff fellas. Use your head for something other than to break your next fall."

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post #3 of 8 Old 12-14-2019, 01:44 PM Thread Starter
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Squirt a little engine oil into the cylinders and try again. If the numbers go up, rings are bad. If they stay just as bad, something in the top end is still wrong....
they all jump up to about 200 psi when I put oil in there. Can I replace just the rings? And is it possible they’re just stuck from sitting so long, because the engine sat for about 4 years
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post #4 of 8 Old 12-14-2019, 03:16 PM
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Hone the cylinders and new rings, minimum.

Riverszzr can tell you whether that's enough. Why did the bike sit for so long? Fuel tank is likely whacked as well, brakes and suspension, chain...... All highly likely to be problems.

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post #5 of 8 Old 12-15-2019, 10:15 AM
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The rings almost certainly had to have rusted to the cylinder wall, in order for all four of them to have failed. Wetting the walls with oil tells you without doubt that the rings are shot.

There has to be a ridge of corrosion byproducts at whatever point on the cylinder wall each of those ring sets stuck. That ridge will cause any new ring to fail to seal as well...... that's why they need to be honed. Just because you can see cross hatching doesn't mean that there is enough roughness to allow another set of rings to match to that surface. Odds are so close to zero of that, it's not worth the effort to find out.

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post #6 of 8 Old 12-15-2019, 06:46 PM Thread Starter
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The rings almost certainly had to have rusted to the cylinder wall, in order for all four of them to have failed. Wetting the walls with oil tells you without doubt that the rings are shot.

There has to be a ridge of corrosion byproducts at whatever point on the cylinder wall each of those ring sets stuck. That ridge will cause any new ring to fail to seal as well...... that's why they need to be honed. Just because you can see cross hatching doesn't mean that there is enough roughness to allow another set of rings to match to that surface. Odds are so close to zero of that, it's not worth the effort to find out.
ok I took the head off the engine again and seen that the head gasket was covered is oil and coolant, the gasket still had it’s spring, material and didn’t seem to be crushed so the loss of compression could be that the head gasket wasn’t sealing like it should’ve, somebody was telling me that the head bolts are torque yield and if you don’t replace them when putting the head back on it won’t seal right. Also I made sure my head wasn’t warped
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post #7 of 8 Old 12-15-2019, 06:46 PM Thread Starter
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Originally Posted by RJ2112 View Post
The rings almost certainly had to have rusted to the cylinder wall, in order for all four of them to have failed. Wetting the walls with oil tells you without doubt that the rings are shot.

There has to be a ridge of corrosion byproducts at whatever point on the cylinder wall each of those ring sets stuck. That ridge will cause any new ring to fail to seal as well...... that's why they need to be honed. Just because you can see cross hatching doesn't mean that there is enough roughness to allow another set of rings to match to that surface. Odds are so close to zero of that, it's not worth the effort to find out.
ok I took the head off the engine again and seen that the head gasket was covered is oil and coolant, the gasket still had it’s spring, material and didn’t seem to be crushed so the loss of compression could be that the head gasket wasn’t sealing like it should’ve, somebody was telling me that the head bolts are torque yield and if you don’t replace them when putting the head back on it won’t seal right. Also I made sure my head wasn’t warped
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post #8 of 8 Old 12-16-2019, 02:26 AM
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If the head gasket was bad, the oil in the cylinders would not have raised compression, same as if the problem was with the valves. Ring to cylinder wall contact, broken/damaged rings are about all that is left.

"Basic stuff fellas. Use your head for something other than to break your next fall."

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