Setting Idle
It is common that the cap is removed from the pilot screw for adjusting the setting. The book is just parroting the emission control laws of the time and is wrong. As soon as you change the exhaust system or the air cleaner you must adjust the pitot screw. Here are my notes ...
Setting The Pilot Screw on Your IronHead
If the carb is old and dirty the pilot screw passage may be gummed up such that you will not be able to "gently seat" the pilot screw reliably. If this is the case remove the carb from the bike and clean it up. Some guys try to do carb work with the carb in the bike. IMO this is a very bad idea.
In the pilot screw passage there should be, in this sequence: screw, spring, washer, o-ring. [Often POs have installed these parts in the wrong sequence; remember that the purpose of the washer is to protect the o-ring from being damaged by the spring]. The screw usually comes out easily. The other parts may require some work. The best technique is to stick a pipe cleaner in the hole, twist it around, and, like magic, out come the other parts on the end of the pipe cleaner.
EDIT: The above info on the pilot screw applies to 1979 and newer carbs. For 78 and older there is nothing in the passage except the screw itself.
1. You need to have easy access to the pilot screw, easy enough to reliably judge "screw it in until gently seated". Loosen the front fuel tank mount bolt; remove the rear fuel tank mount bolt; prop the rear of the fuel tank up on a piece of 2X4; on some bikes this will not be necessary.
2. With the engine cold [so you do not burn your fingers] turn the pilot screw in clockwise until it is gently seated. Count the number of 1/4 turns as you do it; write the number down. Back it out to the original setting. You may need to return reliably to this setting after experimenting.
The "normal" starting point for this process is 1,1/4 [according to the 79 - 85 FM] or 1,1/2 [according to usual practice] turns out.
EDIT: An old HotXL magazine article recommends for Keihin butterfly carbs between 1/4 and 1,1/4 turns out. My experience is that this works best. If you are more than 1,1/4 turns out your pilot jet is too small.
3. The engine must be at full warm up. It will have very hot parts; to avoid burned fingers have a well lighted, comfy place to work.
4. Set the engine idling at about 1000 RPM. You want it to be idling at the slowest speed that is consistent with a smooth idle so that you can hear or feel slight changes.
5. Turn the pilot screw in clockwise until the engine idle becomes worse; tending to stall. Count the number of 1/4 turns as you do this. Then turn the pilot screw out counter clockwise until the engine idle gets good, then becomes worse, tending to stall. Count the number of 1/4 turns as you do this.
6. The best setting for your bike will be somewhere between these two settings. The FM says to use the leanest setting [most screwed in] consistent with a good idle quality. Some guys say to go between the two settings.
It should be between 1/2 and 1,1/2 turns out from gently seated. If it is not within this range you should change the slow jet.
EDIT: I follow the advice from the old HotXL mag article - set it between 1/2 and 1,1/4 turns out.
7. You may have to adjust the idle speed.
8. Make sure that the spark plugs are clean, then ride the bike around your neighborhood for 10 minutes. Keep it under about 15 MPH so that you are on the "idle port", not the "idle transfer ports", the "mid range port", or the "main jet" [see carb diagrams in FM]. Hopefully the plugs will come out a nice medium gray or tan color. If they are too dark you can screw it in another 1/4 turn; too light screw it out 1/4 turn, and try the ride again.
9. If they are really light or really dark the problem may not be with the pilot screw setting. For example, too light might mean an intake or exhaust leak, and too dark might mean the slow jet is too large [among other possibilities].
10. My experience with this process is that after making a change i have to clean the plugs and go for a good ride [say, a half hour or more] before i can trust that the new results are reliable.
Setting The Pilot Screw on Your IronHead
If the carb is old and dirty the pilot screw passage may be gummed up such that you will not be able to "gently seat" the pilot screw reliably. If this is the case remove the carb from the bike and clean it up. Some guys try to do carb work with the carb in the bike. IMO this is a very bad idea.
In the pilot screw passage there should be, in this sequence: screw, spring, washer, o-ring. [Often POs have installed these parts in the wrong sequence; remember that the purpose of the washer is to protect the o-ring from being damaged by the spring]. The screw usually comes out easily. The other parts may require some work. The best technique is to stick a pipe cleaner in the hole, twist it around, and, like magic, out come the other parts on the end of the pipe cleaner.
EDIT: The above info on the pilot screw applies to 1979 and newer carbs. For 78 and older there is nothing in the passage except the screw itself.
1. You need to have easy access to the pilot screw, easy enough to reliably judge "screw it in until gently seated". Loosen the front fuel tank mount bolt; remove the rear fuel tank mount bolt; prop the rear of the fuel tank up on a piece of 2X4; on some bikes this will not be necessary.
2. With the engine cold [so you do not burn your fingers] turn the pilot screw in clockwise until it is gently seated. Count the number of 1/4 turns as you do it; write the number down. Back it out to the original setting. You may need to return reliably to this setting after experimenting.
The "normal" starting point for this process is 1,1/4 [according to the 79 - 85 FM] or 1,1/2 [according to usual practice] turns out.
EDIT: An old HotXL magazine article recommends for Keihin butterfly carbs between 1/4 and 1,1/4 turns out. My experience is that this works best. If you are more than 1,1/4 turns out your pilot jet is too small.
3. The engine must be at full warm up. It will have very hot parts; to avoid burned fingers have a well lighted, comfy place to work.
4. Set the engine idling at about 1000 RPM. You want it to be idling at the slowest speed that is consistent with a smooth idle so that you can hear or feel slight changes.
5. Turn the pilot screw in clockwise until the engine idle becomes worse; tending to stall. Count the number of 1/4 turns as you do this. Then turn the pilot screw out counter clockwise until the engine idle gets good, then becomes worse, tending to stall. Count the number of 1/4 turns as you do this.
6. The best setting for your bike will be somewhere between these two settings. The FM says to use the leanest setting [most screwed in] consistent with a good idle quality. Some guys say to go between the two settings.
It should be between 1/2 and 1,1/2 turns out from gently seated. If it is not within this range you should change the slow jet.
EDIT: I follow the advice from the old HotXL mag article - set it between 1/2 and 1,1/4 turns out.
7. You may have to adjust the idle speed.
8. Make sure that the spark plugs are clean, then ride the bike around your neighborhood for 10 minutes. Keep it under about 15 MPH so that you are on the "idle port", not the "idle transfer ports", the "mid range port", or the "main jet" [see carb diagrams in FM]. Hopefully the plugs will come out a nice medium gray or tan color. If they are too dark you can screw it in another 1/4 turn; too light screw it out 1/4 turn, and try the ride again.
9. If they are really light or really dark the problem may not be with the pilot screw setting. For example, too light might mean an intake or exhaust leak, and too dark might mean the slow jet is too large [among other possibilities].
10. My experience with this process is that after making a change i have to clean the plugs and go for a good ride [say, a half hour or more] before i can trust that the new results are reliable.
Cylinder Compression And Leakage Tests
A compression test should be done as part of any 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 any 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. Should be able to find a small sausage style for under $100.00.
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. Run the engine to get it up to operating temperature
2. Disconnect and remove both spark plugs
3. Screw the compression tester into the spark plug hole for either of the cylinders
4. Lock the throttle open, and ensure the choke plate is also open
5. Crank the engine through several rotations until there is no further increase in reading at the tester guage
6. Record the final reading
7. Repeat for the other cylinder
The difference between the two readings should not be more than 10 psi. A low reading on one cylinder indicates possible valve or ring dammage 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 teardown: 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. The piston must be positioned such that both the intake and exhaust valves are closed. To accomplish this, set the cylinder to be tested precisely at top dead center [TDC] of the compression stroke, as follows:
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 here to have either a shop assistant or a wide "wingspan".
Keep a thumb pressed on the spark plug hole while rotating the back wheel. On the compression stroke you will definitely feel the air pressure working against your thumb.
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.
2. Turn on the compressor, connect the gauge to the air pressure, and adjust the gauge
3. Thread the adapter into the spark plug hole and into the gauge
4. The gauge now shows the amount of leakage
5. Listen at each exhaust pipe. Excessive hissing here indicates the respective exhaust valve is not sealing
6. Listen at the A/C intake. Excessive hissing here indicates intake valve[s] not sealing
7. Listen at the timing plug hole. Excessive hissing here indicates the rings are not sealing
8. Listen around the cylinder/head connection. Excessive hissing here indicates the respective head gasket is not sealing
Notes
The piston must be positioned so that both valves are closed
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.
There are many variables here [engine temperature, precise piston position, whatever] so the test results will not be consistent from one test to the next.
A compression test should be done as part of any 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 any 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. Should be able to find a small sausage style for under $100.00.
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. Run the engine to get it up to operating temperature
2. Disconnect and remove both spark plugs
3. Screw the compression tester into the spark plug hole for either of the cylinders
4. Lock the throttle open, and ensure the choke plate is also open
5. Crank the engine through several rotations until there is no further increase in reading at the tester guage
6. Record the final reading
7. Repeat for the other cylinder
The difference between the two readings should not be more than 10 psi. A low reading on one cylinder indicates possible valve or ring dammage 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 teardown: 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. The piston must be positioned such that both the intake and exhaust valves are closed. To accomplish this, set the cylinder to be tested precisely at top dead center [TDC] of the compression stroke, as follows:
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 here to have either a shop assistant or a wide "wingspan".
Keep a thumb pressed on the spark plug hole while rotating the back wheel. On the compression stroke you will definitely feel the air pressure working against your thumb.
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.
2. Turn on the compressor, connect the gauge to the air pressure, and adjust the gauge
3. Thread the adapter into the spark plug hole and into the gauge
4. The gauge now shows the amount of leakage
5. Listen at each exhaust pipe. Excessive hissing here indicates the respective exhaust valve is not sealing
6. Listen at the A/C intake. Excessive hissing here indicates intake valve[s] not sealing
7. Listen at the timing plug hole. Excessive hissing here indicates the rings are not sealing
8. Listen around the cylinder/head connection. Excessive hissing here indicates the respective head gasket is not sealing
Notes
The piston must be positioned so that both valves are closed
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.
There are many variables here [engine temperature, precise piston position, whatever] so the test results will not be consistent from one test to the next.
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 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.
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.
8. Install the spring keepers, top end first, by prying them in under the bottom with a flat blade screwdriver.
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 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.
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.
8. Install the spring keepers, top end first, by prying them in under the bottom with a flat blade screwdriver.
Do things in this sequence ...
1. adjust pushrods - must! be cold engine
2. set pilot screw - must! be fully warmed up
3. check cylinder compression - must! be warmed up
4. check ignition timing - warmed up probably better
1. adjust pushrods - must! be cold engine
2. set pilot screw - must! be fully warmed up
3. check cylinder compression - must! be warmed up
4. check ignition timing - warmed up probably better
Road Captain
Joined: Oct 2010
Posts: 566
Likes: 3
From: rural ontario
+1 on what everybody said....I slept in this morning and didn't get a chance to jump in on this (dammit), and I don't think there is anything else to add.
I think I shall add this thread to my fav's it reads well for others with similar issues.
I think I shall add this thread to my fav's it reads well for others with similar issues.
Thread Starter
|
Cruiser
Joined: Oct 2010
Posts: 165
Likes: 0
From: Houston Texas
Will do
IRONGEAR-IRONMICK-SCOTTFISHER.
I have downloaded all instructions and will start doing this some of it today, i will only report when i have something meaningful to say, but it will all be done.
Thanks for the info, it is so much good stuff am not sure we have people at dealers here that have this wealth of information.
I have downloaded all instructions and will start doing this some of it today, i will only report when i have something meaningful to say, but it will all be done.
Thanks for the info, it is so much good stuff am not sure we have people at dealers here that have this wealth of information.
Thread Starter
|
Cruiser
Joined: Oct 2010
Posts: 165
Likes: 0
From: Houston Texas
Finding Carb rebuild kit locally
I went to the near me beautiful Harley Dealer, not many customers there because of very cold weather. walked up to the counter. parts guy is a helpfull 21 year old kid
I-Hello, i need a carb rebuild kit for a 1981 Harley Ironhead sportster.
Kid- WOW looked at book briefly then said i have to go back there and look.
I -looking around for about 5 minutes and kid came back
Kid- I found one kit that says 1976 on it, you want to look at it?
I- yes let me see... Hmmmm. there are some parts here that look like they work so i take it.
Kid- When you said 81 am thinking we dont have anything like that.
I- Yes she is older than you are, laugh
The kit is not for my bike specific, it has at least 4 gaskets that are for other models, but i was able to replace all the o-rings, gaskets and diaphragm with it. ( the parts i used are identical to my parts )
I-Hello, i need a carb rebuild kit for a 1981 Harley Ironhead sportster.
Kid- WOW looked at book briefly then said i have to go back there and look.
I -looking around for about 5 minutes and kid came back
Kid- I found one kit that says 1976 on it, you want to look at it?
I- yes let me see... Hmmmm. there are some parts here that look like they work so i take it.
Kid- When you said 81 am thinking we dont have anything like that.
I- Yes she is older than you are, laugh
The kit is not for my bike specific, it has at least 4 gaskets that are for other models, but i was able to replace all the o-rings, gaskets and diaphragm with it. ( the parts i used are identical to my parts )
Good story.
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Thread Starter
|
Cruiser
Joined: Oct 2010
Posts: 165
Likes: 0
From: Houston Texas
Pilot screw setting
I took out the pilot screw again and made sure it was ok, i screw it in all the way and back out 1 1/4 turn, the passage is clean and all the way in it kills the engine, so no change.
I got the bike ready to check timing, but at this point i refuse to get sprayed with oil while i try to look for something am not used to look for.
So i wait for little sight glass to come in before proceeding.
I got the bike ready to check timing, but at this point i refuse to get sprayed with oil while i try to look for something am not used to look for.
So i wait for little sight glass to come in before proceeding.
Road Captain
Joined: Oct 2010
Posts: 566
Likes: 3
From: rural ontario
The thing I find funny about you and your bike, Neal, is that I have an '81 dodge Ram and I never think of it as old. I have a newer Jeep Cherokee that I use daily but the Ram is still used; it is just the 'truck'. My kids drive, so, I keep it for them to use or 'just in case' for me to use. My wife hates it and won't get into it. (she drives the h..o..n..d..a..)
My bike is '61 and I am just starting to feel it is getting old now after having difficulties getting parts as I was re-doing it.
My bike is '61 and I am just starting to feel it is getting old now after having difficulties getting parts as I was re-doing it.