1995 compression issues
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1995 compression issues
Purchased a 1995 f3 a few weeks ago. Actually brought a compression tester to the sale, but was unable to test (as I didn't realize these had a 10mm spark plug, So tiny!)
well, i got it home, I had low compression is all cylinders. (1-150, 2-50, 3-125, 4-150) so I did the valves. All of the intakes were very tight.
Valve job went well ans are not in specs. Compression jumped to 180psi in cylinder 1 and 4, but 2 is only 80psi and 3 is 145.
If I have to tear the case in half to bore these cylinders, is it even worth it!?
well, i got it home, I had low compression is all cylinders. (1-150, 2-50, 3-125, 4-150) so I did the valves. All of the intakes were very tight.
Valve job went well ans are not in specs. Compression jumped to 180psi in cylinder 1 and 4, but 2 is only 80psi and 3 is 145.
If I have to tear the case in half to bore these cylinders, is it even worth it!?
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Joined: Aug 2006
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From: South Florida, USA
I think it depends on a number of things. What is your goal with the bike? That low of compression seems like it wasn't very well maintained. What other things might be wrong with the engine? What would a known good replacement cost? Have you looked at the cylinder walls? How do they look? Maybe just bad rings.
Considering you can't use it as is, it probably doesn't hurt to split the case and see if there are any other expensive things to repair, like crankshaft bearing journals or others that would sway your decision one way or another.
Considering you can't use it as is, it probably doesn't hurt to split the case and see if there are any other expensive things to repair, like crankshaft bearing journals or others that would sway your decision one way or another.
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Joined: Mar 2011
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I think it depends on a number of things. What is your goal with the bike? That low of compression seems like it wasn't very well maintained. What other things might be wrong with the engine? What would a known good replacement cost? Have you looked at the cylinder walls? How do they look? Maybe just bad rings.
Considering you can't use it as is, it probably doesn't hurt to split the case and see if there are any other expensive things to repair, like crankshaft bearing journals or others that would sway your decision one way or another.
Considering you can't use it as is, it probably doesn't hurt to split the case and see if there are any other expensive things to repair, like crankshaft bearing journals or others that would sway your decision one way or another.
Cylinder walls looked perfect once I got in there luckily. Guess we'll hope and pray that the compression is saved once we get it back on.
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Joined: May 2011
Posts: 1,988
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From: Mesa, AZ
Could be carbon-buildup and clogged rings. Do hail-mary last attempt with piston-soak.
1. remove plugs,
2. spray 7-10s of PB-Blaster down each spark-plug hole
3. gently lay plug over hole and let sit for 2-3 hrs
4. add 2-3cc 50/50 acetone/ATF mix
5.gently lay plug over hole and let sit for 2-3 hrs let sit for 2-3 hrs
6. remove plugs, lay rag over opening
7. crank engine 5-10s to blow out excess fluid
8. re-test compression
I've brought lots of engines back this way due to clogged rings.
1. remove plugs,
2. spray 7-10s of PB-Blaster down each spark-plug hole
3. gently lay plug over hole and let sit for 2-3 hrs
4. add 2-3cc 50/50 acetone/ATF mix
5.gently lay plug over hole and let sit for 2-3 hrs let sit for 2-3 hrs
6. remove plugs, lay rag over opening
7. crank engine 5-10s to blow out excess fluid
8. re-test compression
I've brought lots of engines back this way due to clogged rings.
Thread Starter
|
Member
Joined: Mar 2011
Posts: 67
Likes: 9
Could be carbon-buildup and clogged rings. Do hail-mary last attempt with piston-soak.
1. remove plugs,
2. spray 7-10s of PB-Blaster down each spark-plug hole
3. gently lay plug over hole and let sit for 2-3 hrs
4. add 2-3cc 50/50 acetone/ATF mix
5.gently lay plug over hole and let sit for 2-3 hrs let sit for 2-3 hrs
6. remove plugs, lay rag over opening
7. crank engine 5-10s to blow out excess fluid
8. re-test compression
I've brought lots of engines back this way due to clogged rings.
1. remove plugs,
2. spray 7-10s of PB-Blaster down each spark-plug hole
3. gently lay plug over hole and let sit for 2-3 hrs
4. add 2-3cc 50/50 acetone/ATF mix
5.gently lay plug over hole and let sit for 2-3 hrs let sit for 2-3 hrs
6. remove plugs, lay rag over opening
7. crank engine 5-10s to blow out excess fluid
8. re-test compression
I've brought lots of engines back this way due to clogged rings.
I've heard "marvel magic mystery oil" and "seafoam" work well too, I guess I forgot to try those options before taking the head off! Someone also mentioned a "leak down test" that I should have done. Someday I'll know everything, but it isn't today
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