Compression test results
#11
10-22-2014, 10:13 PM
Join Date: Sep 2014
Location: Poke County, MO
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Ok, The fan makes since.
I could ride it around a little more out in the country. Carry the title with me to show I just bought it. Sheriffs around here are pretty good. I think they would let me go in the rare chance if I was to get pulled over. Just being a Truck Driver any tickets I get have to be reported to my Company. I'm pretty well known for not getting tickets. Would be embarrassing to get one.
I could ride it around a little more out in the country. Carry the title with me to show I just bought it. Sheriffs around here are pretty good. I think they would let me go in the rare chance if I was to get pulled over. Just being a Truck Driver any tickets I get have to be reported to my Company. I'm pretty well known for not getting tickets. Would be embarrassing to get one.
#12
10-23-2014, 07:43 AM
Since we are on the topic of compression tests, here are some reasons i do them regularly ...
When pushrods go out of adjustment they almost always get too tight; then the valves do not fully close and a compression test will read low on that cylinder. A compression test is much easier to do than a pushrod check. I do it at about the same frequency as oil changes. I do it immediately at the end of a ride.
If i get a low reading i set the bike up in the evening to adjust the pushrods, then do the adjustment first thing in the morning. This splits the job into two quick parts, and gets the adjustment done on a stone cold engine which is a requirement.
It is also good to be aware on a continuing basis of the condition of the engine. In addition to the compression test i do regular stethoscope tests. So i am always familiar with the way the engine sounds when nothing is wrong, and i can more quickly ID a problem.
I have put on about 40,000 miles in the three years since the top end was last rebuilt. The compression test has been more or less steady at 150F/150R. It has been as much as 8000 miles between pushrod adjustments. Each listening point sounds like steel parts rotating; the generator is the noisiest part of the engine.
Some notes ...
Cylinder Compression And Leakage Tests
A compression test should be done as part of each tuneup. Record the results and follow any changes over time.
A cylinder leakage test should be done any time you are considering taking down the top end. This test gives you useful information regarding what you should look for when you have it apart.
Each of these requires a tester which you can buy at an auto parts store. A compression tester could be found for about $40.00 more or less, and a clyinder leakage tester for somewhat more than that amount. With the cylinder leakage tester you will also need a small air compressor.
Use these tools once and they have paid for themselves, compared to paying $50.00 to $100.00 per hour at a shop. Buy a slightly larger air compressor [look for about 5 CFM @ 90 PSI] and you will be able to use it with air tools.
Compression Test
1. Ride the bike to get the engine up to operating temperature
2. Disconnect and remove both spark plugs; insert them into the leads and place them on the cylinder heads for grounding. Best to use a clip to attach them to the heads, especially if doing a kick start
3. Screw the compression tester into the spark plug hole for either of the cylinders
4. Hold the throttle open, and ensure the choke plate is also open [choke **** pushed in]
5. Crank the engine through several rotations until there is no further increase in reading at the tester gauge
6. Record the final reading
7. Repeat for the other cylinder
The difference between the two readings should not be more than 10%. A low reading on one cylinder indicates possible valve or ring damage to that cylinder. To determine which, pour about 1/2 oz of oil into that cylinder through the spark plug hole and repeat the test. If the reading returns to normal then valves are good, rings may be defective. If compression does not return to normal then valves may require service.
Cylinder Leakage Test
This test will tell you what to look for at the top end tear down: worn exhaust valves, worn intake valves, leaky head gaskets, or worn rings.
This test is usually done immediately following a compression test. So the engine is at or close to normal operating temperature, and the spark plugs have been removed.
1. Remove the pushrods to ensure that the valves are closed.
2. Set the cylinder to be tested at or near top dead center [TDC] as this is the wear area for the rings ...
a] rear wheel off the ground, shift to 2nd gear, rotate wheel until it clicks, repeat until you get to 4th gear. Now by rotating the rear wheel you are rotating the engine. Almost impossible with the plugs in; very difficult in lower gears. For the following it helps to have either a shop assistant or a wide "wingspan".
b] you can see in thru the spark plug hole, especially with a flash light. You can also try inserting something soft like a pencil and watch it rise and fall as you rotate the engine with the back wheel; but be careful it does not break or get stuck! You will have to hang on to the pencil with left hand while rotating the rear wheel with the right.
3. Turn on the compressor, connect the gauge to the air pressure, and adjust the gauge
4. Thread the adapter into the spark plug hole and attach to the gauge
5. The gauge now shows the amount of leakage
6. Listen at each exhaust pipe. Excessive hissing here indicates the respective exhaust valve is not sealing
7. Listen at the A/C intake. Excessive hissing here indicates intake valve[s] not sealing
8. Listen at the timing plug hole. Excessive hissing here indicates the rings are not sealing
9. Listen around the cylinder/head connection. Hissing here indicates the respective head gasket is not sealing
A mechanics stethoscope [with the probe removed for this test] makes a good listening device, as does a length of oil line hose.
Greater leakage results in a sound of lower pitch.
There will always be some leakage, especially past the rings.
Ironhead Push Rod Adjustment
Do this procedure with the engine stone cold. I usually do it first thing in the morning.
1. Remove the spark plugs. Remove A/C to make room to work.
2. Using a flat blade screwdriver pry the spring keeper off of each push rod; the bottom of the keeper pops out first, then the top. Alternately, use a 3/4" open end wrench to push down on the top of the spring retainer, then pry out the spring keeper with the screwdriver.
3. The lower push rod covers may be stuck tight against the bottom o-rings, but they can be loosened by pinching between thumb and finger [or carefully using a shop rag and a pliers] and twisting or rotating. Lift these up and secure each with a tall-S-shaped piece of 12 or 14 gauge household wire [not cable] [or a long piece of Plumbers solder such as 95/5 hooked over the rocker cover and under the push rod cover.
4. Jack up back end of the bike so that rear wheel is off the ground, shift to 2nd gear, rotate wheel until it clicks, repeat until you get to 4th gear. Now by rotating the rear wheel you are rotating the engine. Almost impossible with the plugs in; very difficult in lower gears.
5. To adjust a particular push rod, its valve must be fully closed [the valve spring is relaxed]. Valve position for a particular cylinder is determined by observing the corresponding push rod of the other cylinder. For example, when the rear cylinder intake valve tappet is raised [valve fully open, spring compressed], the front cylinder intake valve is fully closed, and the front intake push rod can be adjusted.
6. Check [and adjust if necessary] the push rods:
[a] use the rear wheel rotate the engine so that the rear cylinder exhaust push rod tappet is fully raised. The front cylinder push rod is adjusted correctly if it has no vertical or horizontal play, and you can just rotate the push rod between thumb and forefinger with no trace of binding or dragging.
[b] to adjust if needed: hold the adjusting screw in place with a wrench; with another wrench loosen the split locknut. Then turn the adjusting screw using fingers only until the pushrod's ball end is seated in the tappet with a "slight amount of play". Then tighten further as follows:
Option 1: Adjust on the tighter end of the range: There should be no vertical or horizontal play, and you should be just able to rotate the push rod between thumb and forefinger with no trace of binding or dragging.
Option 2: Adjust on the looser end of the range: Set the adjusting screw to finger tight so that you cannot turn the push rod between forefinger and thumb. Undo it a tiny bit so that it is just barely loose. Then loosen it 1 "side" for an exhaust or 1/2 "side" for an intake. "Side" refers to one side of the 6-sided adjusting nut.
EDIT: Experience here is that Option 2 is the better and most likely the correct choice.
[c] hold the adjusting screw in place with the one wrench; with fingers then the other wrench tighten the locknut.
[d] recheck the adjustment; it is common for the adjustment to go out as you do step [c], in which case [b] and [c] must be redone.
[e] repeat for the other push rods.
[f] rotate the engine checking each pushrod.
7. Use a flat blade screwdriver to push the upper push rod covers up, and seat them into the upper o-ring or cork washer that is in the rocker cover.
8. Install the spring keepers, top end first, by prying them in under the bottom with a flat blade screwdriver.
Using A Stethoscope
The "sound" can be quite disturbing, very much like the engine is going to blow up. Litterally like a tin can of marbles. What you need to do is to determine if it is the normal sound or if something is wrong.
The best way to do this is to listen with a mechanics stethoscope. You can use a screwdriver or a length of hose but the real tool is much better, and can be purchased inexpensively at Princess Auto or Harbor Freight.
With the engine at idle listen at ...
If a pushrod is too loose you may hear a louder click sound at its lifter block. If you adjust the pushrods according to the looser option in the Sticky you may hear this click on the exhaust pushrods, slightly louder than at the intakes.
It is worthwhile to do this process a couple of times a year, just to keep track of stuff. It is a very good idea to do this when the engine is running well so that you know what running well sounds like thru the stethoscope.
When pushrods go out of adjustment they almost always get too tight; then the valves do not fully close and a compression test will read low on that cylinder. A compression test is much easier to do than a pushrod check. I do it at about the same frequency as oil changes. I do it immediately at the end of a ride.
If i get a low reading i set the bike up in the evening to adjust the pushrods, then do the adjustment first thing in the morning. This splits the job into two quick parts, and gets the adjustment done on a stone cold engine which is a requirement.
It is also good to be aware on a continuing basis of the condition of the engine. In addition to the compression test i do regular stethoscope tests. So i am always familiar with the way the engine sounds when nothing is wrong, and i can more quickly ID a problem.
I have put on about 40,000 miles in the three years since the top end was last rebuilt. The compression test has been more or less steady at 150F/150R. It has been as much as 8000 miles between pushrod adjustments. Each listening point sounds like steel parts rotating; the generator is the noisiest part of the engine.
Some notes ...
Cylinder Compression And Leakage Tests
A compression test should be done as part of each tuneup. Record the results and follow any changes over time.
A cylinder leakage test should be done any time you are considering taking down the top end. This test gives you useful information regarding what you should look for when you have it apart.
Each of these requires a tester which you can buy at an auto parts store. A compression tester could be found for about $40.00 more or less, and a clyinder leakage tester for somewhat more than that amount. With the cylinder leakage tester you will also need a small air compressor.
Use these tools once and they have paid for themselves, compared to paying $50.00 to $100.00 per hour at a shop. Buy a slightly larger air compressor [look for about 5 CFM @ 90 PSI] and you will be able to use it with air tools.
Compression Test
1. Ride the bike to get the engine up to operating temperature
2. Disconnect and remove both spark plugs; insert them into the leads and place them on the cylinder heads for grounding. Best to use a clip to attach them to the heads, especially if doing a kick start
3. Screw the compression tester into the spark plug hole for either of the cylinders
4. Hold the throttle open, and ensure the choke plate is also open [choke **** pushed in]
5. Crank the engine through several rotations until there is no further increase in reading at the tester gauge
6. Record the final reading
7. Repeat for the other cylinder
The difference between the two readings should not be more than 10%. A low reading on one cylinder indicates possible valve or ring damage to that cylinder. To determine which, pour about 1/2 oz of oil into that cylinder through the spark plug hole and repeat the test. If the reading returns to normal then valves are good, rings may be defective. If compression does not return to normal then valves may require service.
Cylinder Leakage Test
This test will tell you what to look for at the top end tear down: worn exhaust valves, worn intake valves, leaky head gaskets, or worn rings.
This test is usually done immediately following a compression test. So the engine is at or close to normal operating temperature, and the spark plugs have been removed.
1. Remove the pushrods to ensure that the valves are closed.
2. Set the cylinder to be tested at or near top dead center [TDC] as this is the wear area for the rings ...
a] rear wheel off the ground, shift to 2nd gear, rotate wheel until it clicks, repeat until you get to 4th gear. Now by rotating the rear wheel you are rotating the engine. Almost impossible with the plugs in; very difficult in lower gears. For the following it helps to have either a shop assistant or a wide "wingspan".
b] you can see in thru the spark plug hole, especially with a flash light. You can also try inserting something soft like a pencil and watch it rise and fall as you rotate the engine with the back wheel; but be careful it does not break or get stuck! You will have to hang on to the pencil with left hand while rotating the rear wheel with the right.
3. Turn on the compressor, connect the gauge to the air pressure, and adjust the gauge
4. Thread the adapter into the spark plug hole and attach to the gauge
5. The gauge now shows the amount of leakage
6. Listen at each exhaust pipe. Excessive hissing here indicates the respective exhaust valve is not sealing
7. Listen at the A/C intake. Excessive hissing here indicates intake valve[s] not sealing
8. Listen at the timing plug hole. Excessive hissing here indicates the rings are not sealing
9. Listen around the cylinder/head connection. Hissing here indicates the respective head gasket is not sealing
A mechanics stethoscope [with the probe removed for this test] makes a good listening device, as does a length of oil line hose.
Greater leakage results in a sound of lower pitch.
There will always be some leakage, especially past the rings.
Ironhead Push Rod Adjustment
Do this procedure with the engine stone cold. I usually do it first thing in the morning.
1. Remove the spark plugs. Remove A/C to make room to work.
2. Using a flat blade screwdriver pry the spring keeper off of each push rod; the bottom of the keeper pops out first, then the top. Alternately, use a 3/4" open end wrench to push down on the top of the spring retainer, then pry out the spring keeper with the screwdriver.
3. The lower push rod covers may be stuck tight against the bottom o-rings, but they can be loosened by pinching between thumb and finger [or carefully using a shop rag and a pliers] and twisting or rotating. Lift these up and secure each with a tall-S-shaped piece of 12 or 14 gauge household wire [not cable] [or a long piece of Plumbers solder such as 95/5 hooked over the rocker cover and under the push rod cover.
4. Jack up back end of the bike so that rear wheel is off the ground, shift to 2nd gear, rotate wheel until it clicks, repeat until you get to 4th gear. Now by rotating the rear wheel you are rotating the engine. Almost impossible with the plugs in; very difficult in lower gears.
5. To adjust a particular push rod, its valve must be fully closed [the valve spring is relaxed]. Valve position for a particular cylinder is determined by observing the corresponding push rod of the other cylinder. For example, when the rear cylinder intake valve tappet is raised [valve fully open, spring compressed], the front cylinder intake valve is fully closed, and the front intake push rod can be adjusted.
6. Check [and adjust if necessary] the push rods:
[a] use the rear wheel rotate the engine so that the rear cylinder exhaust push rod tappet is fully raised. The front cylinder push rod is adjusted correctly if it has no vertical or horizontal play, and you can just rotate the push rod between thumb and forefinger with no trace of binding or dragging.
[b] to adjust if needed: hold the adjusting screw in place with a wrench; with another wrench loosen the split locknut. Then turn the adjusting screw using fingers only until the pushrod's ball end is seated in the tappet with a "slight amount of play". Then tighten further as follows:
Option 1: Adjust on the tighter end of the range: There should be no vertical or horizontal play, and you should be just able to rotate the push rod between thumb and forefinger with no trace of binding or dragging.
Option 2: Adjust on the looser end of the range: Set the adjusting screw to finger tight so that you cannot turn the push rod between forefinger and thumb. Undo it a tiny bit so that it is just barely loose. Then loosen it 1 "side" for an exhaust or 1/2 "side" for an intake. "Side" refers to one side of the 6-sided adjusting nut.
EDIT: Experience here is that Option 2 is the better and most likely the correct choice.
[c] hold the adjusting screw in place with the one wrench; with fingers then the other wrench tighten the locknut.
[d] recheck the adjustment; it is common for the adjustment to go out as you do step [c], in which case [b] and [c] must be redone.
[e] repeat for the other push rods.
[f] rotate the engine checking each pushrod.
7. Use a flat blade screwdriver to push the upper push rod covers up, and seat them into the upper o-ring or cork washer that is in the rocker cover.
8. Install the spring keepers, top end first, by prying them in under the bottom with a flat blade screwdriver.
Using A Stethoscope
The "sound" can be quite disturbing, very much like the engine is going to blow up. Litterally like a tin can of marbles. What you need to do is to determine if it is the normal sound or if something is wrong.
The best way to do this is to listen with a mechanics stethoscope. You can use a screwdriver or a length of hose but the real tool is much better, and can be purchased inexpensively at Princess Auto or Harbor Freight.
With the engine at idle listen at ...
- all 4 rocker ends, both sides of the engine
- all 4 pushrods, top, middle and bottom
- all 4 lifter blocks
- all 4 cams, listening thru the gearcase cover
- both ends of the generator
If a pushrod is too loose you may hear a louder click sound at its lifter block. If you adjust the pushrods according to the looser option in the Sticky you may hear this click on the exhaust pushrods, slightly louder than at the intakes.
It is worthwhile to do this process a couple of times a year, just to keep track of stuff. It is a very good idea to do this when the engine is running well so that you know what running well sounds like thru the stethoscope.
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