I have a 1980 ironhead sporster that I just finshed completely rebuilding from the frame up. I put new jugs (well new to me, they are oem 80 jugs that came with pistons that were bored .020 over) on it with new rings. I got a used set of heads for her as well, also oe tjeu are 83, I also put a new primary chain and primary chain tensioner as well, I have an s&s super "e" shorty carburetor and intake, it also has an ultima digital ignition with a crane cams single fire coil. Now that I got the bike togather and running, im haveing a problem with the front cylinder showing signs of burning oil (oily residue inside the exhaust pipe) and ocasionally some white smoke, but the smokeing problem has started to go away, and for the first few days that I rode the bike I had no smoking problems, then I took it to this guy I met who has a shop, asked him to cheek the timeing and adjust the carb, and thats when the smoke problem started. He says its rings, but they are brand new, had a good break in and on top of that the smokeing is starting to stop, im just worried ill have to go threw my topend again. I recently reset the carb to factory settings and am going to adjust it myself (just the bikes out of gas and I have to go fill a can to get gas in her again) but when thats done im confident that I can get the carb set but as to the okay do you knowwhite smoke what could it be? What should I do? Thanks for the help

 

you say there are new rings in it, did you put them in? if so who did the hone on the cylinders? if you did not have a good hone put on them there is your problem, cant just throw rings in they will never seat right,also you say you got a used set of heads, were the guides and valves checked out? these things can be very hard on valve guides witch will lead to smoke, also i would take that super paper wheight of a carb and e bay it and get a carb thats easier to deal with lol maybe a cv conversion? your ignition set up sounds good,ill bet you will be doin the top end again

 

How do the plugs look? My indie told me that if it was running rich it would produce white smoke...leaned mine out no white smoke.

T-Ron

 

I bought the heads and pistons as a set, they came pre bored and honed, I put the new rings in according to the book, tomorrow im going to tune out the card, but it only smoked on me for about two or three days then it stoped, was told by a local shop that they think its a valve not seating properly, the spark plugs are brandnew NGKs, I gaped them according to the book, the heads wernt cheeked, didnt have the funds to do it, but was told they were on a running rat bike, but that can only get me so far, kinda rolled the dice hopeing they were as good as my old ones, (old ones didnt fit the new,jugs, found out the,old heads and jugs were 71-e72, I put 80 jugs back on the 80 motor) im makeing 120 psi of compression on bolth cylinders. Im thinking I got a faulty valve guide on the front cylinder.but not 100% on that trying to narrow,it down to what it could be before I tear it down that is if I have to

 

I wonder if the smokong, since it has stopped, was from assembly lube?

Spark plug gap should be .040 for electronic ignition or .030 for points ignition.

120 compression is minimum for a good engine but is OK, especially if both cylinders tested about the same. The cylinder compression test must be done with the engine at full operating temperature and with the throttle fully open [and with the choke plate fully open as well - the **** pushed all the way in]. If not done correctly the readings will be low and actual compression will be much higher.

I am not trusting the guy who checked the carb and the timing. I would check these both myself. Here are some notes ...

Setting The Ignition Timing on Your IronHead

1. Checking vs Setting the Ignition Timing

You can check the timing without changing anything. Changing the timing can be done by one person but is easier with two. The ignition module or points is on the right side of the bike, the timing hole is on the left side. Easier with one person on each side than to go back and forth. Standard advance for the 1980 XL is 40`. I have mine set at about 35`. At 38` i get pinging.

2. Equipment That You Need

You need an induction timing light which you can buy at any auto supply store. Best to get the "dial back" type. These allow you to set a number [like 35`] into the timing light and then adjust the ignition module/points backplate until you are there.

If you have very well insulated spark plug wires the timing light may not sense the signal thru the wire. If this is the case then open the gap on the spark plug to 050 or more. Reset it to your normal gap [030 for points or 040 for electronic] when done with this procedure.

It also helps to have a throttle lock as the timing should be checked/set with the engine at 2500 RPM.

You will need a piece of rubber oil line hose about 1 inch long. Press one end up against the side of a stone grinding wheel [or whatever] to make sure it is perfectly flat.

3. Front Cylinder: TDC Mark vs Advance Timing Mark

The TDC [Top Dead Center] mark is used with a dial back timing light to check the timing, or to set the timing at a specific degree, such as 37`. The advance timing mark is used to set the timing to the factory setting, such as 40`. Best is to use a dial back timing light to check or set timing.

4. To Identify Your Front Cylinder TDC Timing Mark

Remove spark plugs. Rear wheel off the ground, shift to 2nd gear, rotate wheel until it clicks, repeat until you get to top gear. Now by rotating the rear wheel you are rotating the engine. Almost impossible with the plugs in; very difficult in lower gears.

You want the front cyl to be at TDC. You can see in thru the spark plug hole, especially with a flash light; you can 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. Helps to have a good wingspan, or an extra person.

With the piston at precisely TDC look in thru the timing hole. You should see a drilled dot or a line. That is your front cylinder TDC mark. Once you know for certain what the TDC mark looks like you can check the timing.

5. Procedure, Checking The Timing

Begin with the engine at operating temperature. Remove the timing plug from the left side of the engine. Insert the 1" hose smooth end first, right tight up against the flywheel. I use a needle nose plier and twist it in there as firmly as i can. If it is not smooth and tight against the flywheel oil will spray out while you are working.

Start the engine, have it at about 2500 to 3000 RPM [it will be extra noisy with the timing plug out], set the timing light at 40`, aim it into the timing hole thru the hose. Click it down one degree at a time while you look for the timing mark. If you don't find it you may have to work up from 40`.

If it is in the 35` to 40` range and there is no pinging then you may wish to leave it as is. With pinging on acceleration you may want to retard it by about 1/16 of an inch or less [see Math below].

6. Procedure, Setting the Timing

Remove the points cover from the right side. You will be rotating the back plate so first mark it so you can get back to the current position if needed. Make a scratch mark or use a permanent magic marker, or better still a small bright red or whatever color paint mark.

To change the timing loosen the two standoffs holding the points/ignition module and rotate the backplate. Clockwise advances [larger degree number] counter-clockwise retards [smaller degree number].

7. Some Math, How Much to Rotate

The backplate has a 3" diameter = 1.5" radius.
The circumference = 2 * pi * radius = 2 * 3.14 * 1.5 inches = 9.42 inches
The circumference = 9.42 * 16 ~= 151 sixteenths of an inch.

One rotation of the backplate corresponds to two rotations of the engine, so it is like a circle that has 2 * 360 = 720 degrees. 720 / 151 ~= 5

Therefore a rotation of the backplate by about 1/16 of an inch results in a timing change of almost 5 degrees!

 

These is written for a Keihin butterfly style carb, but the princilpes are the same for all carbs ...

Cleaning a Carb

1. Removing it from the bike should be straight forward. First thing when it is out is to check the pilot screw setting. Turn it all the way in until gently seated counting the number of 1/4 turns; then write this number down; then reset it.

2. I put mine in a vice to remove the screws, and for much of the following work. Wrap in a shop towel; close the vice gently taking extra care with the choke and throttle linkages. The vice is a needed extra pair of hands.

EDIT: A better choice than a plain vice ...


Better one ...



3. You must be very careful handling the float so as to not change the level. You should have the official specs for setting the level as in the FM, and check it, every time you dismantle the carb, as the last thing before putting it back together.

4. The jets are made of brass, a soft metal that is easily damaged. Use an exact correct size screwdriver. I ground a medium flat blade screwdriver down to exact size on my bench grinder to access the slow jet.

5. The general appearance of the inside of the carb is not necessarily a good indication of its condition. It can look spotless and have clogged jets, or look cruddy and have clear jets.

6. Clean each individual part. Do not allow any solvents to contact any rubber parts [tip of needle, o-ring seal for bowl]

7. Make a list of all of the jets and passages for your carb using the carb manual or the FM for the bike. Then ensure that you can blow either compressed air or carb cleaner thru each one.

8. Remove the pilot screw and clean the parts and the passage. The passage contains in this sequence: pilot screw, spring, washer, o-ring. These are very small parts, especially the washer and o-ring. Usually the spring will easily fall out. One time i thought the spring was not in there because it would not fall out; i obtained a new spring and could not get it in! The technique for removing the washer and o-ring is to use a pipe cleaner: stick it in the hole, twist it around, remove it - you should see the washer and o-ring on the end of the pipe cleaner.

EDIT: the washer and o-ring are part of the pilot screw assembly for 1979 on. They are not in the 1978 and earlier Keihin carbs.

Remember that the purpose of the washer is to protect the o-ring from the spring and you will always get them back in in the correct sequence.

9. Dismantle the accelerator pump assembly noting carefully the sequence and orientation of the parts. Clean and inspect the parts. Replace the diaphragm if it is cracked.

10. Check the float level then carefully put it back together. I personally find it very confusing trying to decide which way to bend the tang if it is not correct. If the fuel level is low is the float high or low? Do i need to bend the tang up or down? On the bench the carb is usually upside down, adding to the confusion. Sort all this out before making an adjustment.

Best to replace the original Phillips screws for the bowl with stainless steel socket head screws.



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. Occasionally 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: Some carbs, noteably 1966 to 1978 Sportster carbs, do not have the o-ring and washer in the pilot screw passage.

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. I usually go for a half hour or so ride outside the city, then ride home with the last 10 minutes at city riding speeds [so that it is 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 is not with the pilot screw setting. For example, too light might mean an intake or exhaust leak, and too dark might mean the pilot 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, an hour or so] before i can trust that the new results are reliable.

 

I got the carb set up good today, the motor doesnt smoke on start up, or running it after warm up, however while sitting at an idol if I crack the throttle it will push a poof of white smoke out of the front cylinder. There is also an oily residue in the front exaust pipe, the rear is good thoe, I do have the spark plugs gaped at .040 I am about to go set the timeing on it then recheek the carb settings. And the cimpression test done on the bike was not done like you said, he just pulled bolth plugs, screwed in the gage, and the turned the key and 120 was what he came up with, like I said, I dont trust the guys knowlage on this bike. It thook me 5min to set the carb up with the proper instructions from s&s and hes has never got it right, id rather do the work on the bike myself, I built her I want to finsh her, but when im not sure on something its nice to have the expert advice, but for my first compleat rebuild of an old harley I think im doing ok lol

 

I am not expert on this so listen to others also ... The smoke after idling will be from some oil leaking down either thru the valve guides [less likely] or past the rings [more likely]. Neither is a serious issue. Can be taken care of next winter or whenever.

Yes, best to do the work yourself. When something is beyond your knowledge, skill or tools ask here forsr then go to a mechanic or machine shop with some knowledgr.

It might be useful to do a cylinder leakage test ...

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. 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. Ride the bike to get the engine to get it 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
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 psi. 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. Excessive hissing here indicates the respective head gasket is not sealing


Notes

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.

 

I would say the poof of smoke when you crack into it is a valve leaking by some. The sudden change in vacuum sucks a small amount of oil into the cylinder, (you are going from 800 to 1200 rpms let's say in a split second.), not a big deal but I'd carry an extra set of plugs with me. One rainy weekend or this winter, pull the rocker boxes and put in a new set of seals.

 

Oops, no valve stem seals in an IronHead engine. Some guys do put them in. Apparently does no harm in the intake sides but must never be installed on the exhausts.

Standard seals require machine work. Floating/umbrella seals can be installed directly.

I never have them in my IronHead.