Ive got 2 problems with my 76 ironhead sportster, and I am looking for some good advice 1st - when I try to start it and it doesn't start right away, about 1/2 cup of fuel pees out of the tube coming off the bottom of the carb onto the floor, and sometimes when I shut it off after running awhile? 2nd------ The starter will not always stay engaged long enough to start the bike, it will crank a few times then disengage and wine to a stop. I know on older cars it is the bendix spring in the starter. Any ideas---------------HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!1

 

Your float operated needle valve in the carb fuel bowl is leaking through. It is dirty or worn out and possibly the float level is a bit out of adjustment. 1/2 cup of gas on the floor is a lot!!
The starter coming out of engagement is strange it should only do that if the engine starts and the ring gear starts spinning faster than the pinion gear. Possibly you have an intermittent open in the starter circuit that in effect shuts down the circuit just like letting go of the starter button.

 

possibly on your first problem you may need to adjust tour fuel bowl float to a lower level. As far as your starter I have a kick-only.

 

It is odd that just 1/2 cup or so of fuel spills out. Usually either it does not overflow or it does not stop until the tank is down to reserve. What may be happening is that there is a piece of crud in the bowl keeping the valve from closing. When fuel starts to flood out the crud gets moved. Here are my notes on cleaning a carb ...

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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.
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The starter will not run reliably unless the battery is fully charged. It is not sufficient to just charge the battery overnight and assume it is fully charged. Some of the large batteries take 24 hours or more to come up to full charge. Best to use an automatic charger [Battery Tender or whatever], or for a liquid filled battery do a specific gravity test. Best also to use a charger of 2 amps or less.

If it still fails with a fully charged battery then it is beyond my knowledge; others will chime in on it.

 

as far as the carb goes, give it a good cleaning as Iron Mick said. For the starter problem, your bendix gear itself may be bad. It has a one way bearing built into it, and it may grab for a little bit, and then start to slip and just free spin. That's what mine did when it failed.

 

Sounds like the 2 problems i have, fixed leak by just cleaning the carb, crud under needle
valve, get yourself a new bendix gear,custom chrome have a six roller instead of the usuall 5 roller gear which i think would have to be better.