almost the same as the '74 thread. ive been slowly getting my '75 together and now im having problems with the rear jug overheating. i dont know how to work on this myself, so ive i had it to 3 different shops only to find no permanent solutions.

ive replaced plugs, wires, coils, oil. had shops replace points, had leakdown and had compression checked. the last work had it running the best. it didnt die on its own, but after i shut it off to fuel up, it wouldnt restart until i let it cool for 30 mins or so.

the last mechanic said what he could tell, the motor is as good as a 75 can be. could this be a simple problem(maybe a new oil cooler) or am i in for a serious payment for rebuild?

 

First of all, tell me this........
What makes you think the rear cylinder is getting hot?
How are you measuring the excessive heat?

I have to ask because myself, I would not be able to tell.
Plugs, coil, oil, wires, points, etc, etc are not going to make a bit of difference regarding the rear cylinder getting hot.
Ditto for the thought of installing an oil cooler. Don't waste your money as it will not make a dime's worth of difference.

So, let's go back to the beginning and tell us what problems you are having.
You say it will not start after it has warmed up? OK, that is one problem.
You say it will not shut off unless you turn off the gas? That's two problems.
What else?
If you are going to ride an ironhead you need to learn a few things regarding working on it yourself. Depending on shop mechanics is a hopeless situation, as they will bleed you dry financially and never get the bike fixed as well as you could do it yourself.
That's what this forum is here for.....to help.
So tell us what specific problems you have and we can take them one at a time and find a solution.
pg

 

+1 on everything that PG said in the above post.

If it will not start when it is fully warmed up the carb may be jetted too rich. This is not necessarily the problem, just a possibility. What carb is in the bike? What jets are in it? How many turns out on the pilot screw?

 

since my first post was to short for some, let me start from the beginning, sorry for the length but maybe you will better understand whats goin on.

i bought a 1975 sportster xlh less than 2 yrs ago. i was told the carb was messed up and timing was way out. the bike would not start. would turn over, which i figure was only because this bike is a kickstart, but wouldnt start. the bike didnt look like much but had potential to be sweet with a face lift and a lil tune up....not the case.

i knew a friend of a friend with a bike shop(harley cert mechnc). of course he mostly does tune ups on late model bikes but i give him a shot. he replaced coil, generator, wiring, plugs n wires and a rebuild kit on the carb.(which is a s&s super shorty) i paid for parts and a lil labor, not bad at all.

i take it home ride it around the nieghborhood a lil and it seems to do ok. next day i take it out for the highway. after a lil more than an hour i come back in town and pull up to a stop light and it dies. (luckily only a few miles from home) i pull to side sit for maybe 15 -20 mins, it fires up and i ride it home. the ride home it ran like crap. missing and died again a few blocks from home.

week or so later i call my buddy(not the harley mechnc, but he works on em a lil). he comes and looks it over. says i fouled the plugs. he adjusts the carb, i put in new plugs and it fires right up. i run up n down the road no problem. next day after riding through town a lil while it dies again. same process til i get home again. after several attempts by myself to adjust the carb(which i know nothing about) and replace the fried plugs, i decide to leave the motor alone for the winter and work on the stuff i know how to do.

winter comes and goes...nothing done to the bike

spring hits and i do a couple months work. pull th gas tank, fenders, oil tank, handle bars, head light, battery tray and take em to get painted. i find several bolts stripped or broken and headlight falls apart. got new brake plate cover, side mount tail light, new kickstand, new shocks, solo seat, battery cover, also have a new triple tree painted and rdy to put on. i get most of it back together and find out i cant getthe conversion kit for new tripl tree n i cant put it on. i bite the bullet and go to the harley shop. tell em i need new tree put on, new headlight, carb checked, oil lines checked, a few broken bolts pulled and replaced and of course get my bike running!

2 months later.....finally get my bike back and they say its running great! i pay them a ton of money and haul my bike home. after i get it home and take it for a short ride to a friends house(8 blocks away) and as i pull in his driveway it dies. i can feel the heat blasting off the motor. it doesnt start again for another 45 mins. i call the harley shop. they say i choked it to long when i started it. few days later i start over, replace the plugs, only use a little choke and close it as soon as it fires. same result, short ride and more fried plugs.

winter....

a few weeks ago, take it to a local shop that builds choppers, i dont know em but what the hell. guys says $100-$1400. i say do it. week later he calls and say compression good, leak down good, put in new points, new plugs, new seals for front forks(started leaking over winter), also traded for some sweet chrome wire wheels and had rims painted black and put on. guy charged me next to nothing for the work. bike is lookin better than ever and i ride it home from the shop(only a few miles) when i get there its still running, sounds great. i take off through town for close to an hour. still running and sounds great, i decide to stop for gas before i test it on the highway. when i turn off the key at the gas station it almost burns my fingers. once again i sit for at least 30 mins. it starts, i ride home, park in garage. plugs black as night.

so now i sit here typing away, hoping that someone understands my situation. i dont know how to work on motors or carbs, but i know i can find people that do. i really like the way my bike looks now, its exactly what i want. but if it dont run, its no use to me and its gone. so if anyone can help, it is much appreciated. thanks

 

Did you shut the fuel petcock off when you stopped to refuel? Could be a mis-adjusted float or leaking needle and seat in the carb letting the gas into the intake while she sits, making it flood out when you go to start it.

What are you running for an air cleaner? If it is overly restrictive, that would make it run rich at high rpms.

I have never played with a S&S carb before, but I think you are running rich, I would check the jet sizes, and probably start with dropping the main jet one size.

Was the ignition switch itself hot when you went to shut it off, as in hot from too much electrical resistance? That can cause scarry problems if left unattended, it is hard to get all the magic smoke back inside wires once it has been let out...

 

could have a couple of problems, i second the out of adj float for the times it wont restart , but lean makes heat, ,maybe a re tuning of the carb is in line?i have never been a fan os the ss line, but maybe you still have intake leaks?

 

PG; I don't think he said he had to cut the gas to get it to shut down. So his only problem it running hot. That would me it hard to start.

What carb are you running? Shorty E? You can find manuals on S&S site. http://www.sscycle.com/modules/tuning/index.php. Find out what size main and intermediate jets you are running. Instructions are in the link. I don't remember what size I run but someone here will know.

What plugs are you running? I don't believe this is the problem but there are hotter plugs. Doesn't hurt to rule it out.

You can also swap the spark plug wires, a cracked coil could cause one cly to miss. I guess that could cause the other to over heat.

You also need to forget about thinking in terms of it running better than before or after so and so worked on it. There is running right and there is running bad. IE It should not stumbling when cruising, even if you don't' think it is so bad compared to how it was running. It is still useful information. You don't have to compromise just because you have a IH.

So I would.

1. Make sure one Cyl it hotter than the other. Can you tell just by putting your had near it on the left side?
2. Make sure my carb has a good baseline per the link above.
3. Make sure the right plugs are being used.
4. Do the wire swap test.

 

The short story is that, regardless of what has been fix or replaced, it will not re-start when the engine is warm. And the plugs come out black. Are they black but just real sooty? or are they black and wet?

The key on my bike does get hot on long runs - not burn my fingers hot, but more than just warm. So i am unsure about this symptom.

It is important to know the carb settings: jet sizes and pilot screw setting. I am not familiar with S&S carbs myself but the tuneing info is available on the S&S website. I think we need to know if the carb is a B or an E or whatever. Anyway, tune up instructions are here ... http://www.sscycle.com Look under TechnicalInformation, then Carb Quick Guide, Instructions, and Tech Tips.

Here are some of my carb notes: Carb cleaning and pilot screw setting. These are written for Keihin carbs but the principles are the same. These notes will get you started doing the work yourself.

After you have the carb off, have confirmed its condition and settings, we can look at other possibilities. When re-installing the carb we will pay particular attention to getting it very very well sealed, and mounted with a support bracket.

Carb Cleaning

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.

3. You must be very careful handling the float so as to not change the level. You must 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. Ignore any advice that says to soak or boil the whole carb in carb cleaner. Rather, 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.

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. [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.

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 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 more] before i can trust that the new results are reliable.

 

Just another thought, maybe the exhaust is restricted. If you run with a restricted exhaust, the plugs are gonna turn black AND it's gonna create too much heat in a hurry(ask me how I know). The first think i'd do is pull the exhaust and make sure it's clear all the way through, and if you have baffles, try running it without them or try a different exhaust.

*edit* - the first thing I would do is use a infrared thermometer to check the head and cyl. temperatures. If you don't have one, you can probably get an inexpensive one at any hobby shop that sells r/c cars that run on nitro (I think I paid $10 for mine) and if your head temps are over 300, then i'd pull the exhaust.

 

thanks guys, ill check out the s&s site and get back here when i can, my schedule is weird so i have limited time to do work on it.

mick when the plugs come out they are black and dry