New issue off of my "dumb oil question" thread.

Background - changed the transmission oil and primary gasket. Figured it would be ready to go and as soon as I pulled the clutch in the bike died and I couldn't get it started.

I've checked the spark plugs (not in great condition, but working) and I've checked to make sure that a spark is coming through them. So I'm pretty sure the Ironhead is not running into any electrical issues.

As the engine was turning over but just not catching I decided to check the fule. My engine has a S&S super e carb with a visible oil filter on the fuel line. I checked the fuel lines and everything seemed fine.

However the bike won't start

Here is what I've done:

1. Taken the oil filter off and oil will run through the hose (stronger than a trickle, but not a gush).
2. Returned the carb to it's default settings.
3. Checked the rest of the line and there is not obstruction.
4. The filter will not fill up with gasoline anymore and when I bypass the filter gas flows out of the bottom of the engine.
5. With fuel in the line the bike will start, rev high (about 20,000 RPMS) then drop down and die.

I figure the issue is either a pump in the carb or perhaps the petcock in the gas tank is blocked. My next steps are to remove the gas tank and check the petcock... after that is there anything else you guys can think of?

 

I would check the float level of the carb and for dirt and crud in the float needle seat. It sounds like your engine is getting way too much fuel, I had a similar issue with my old keihin butterfly carb. It would pee gas all over once I turned the petcock on. After I "solved" that it would run only at a high idle of 1800-2000 RPMs and would bog at speed.

Are your spark plugs coated with a black soot? Does it smell like raw gasoline when you are turning the engine over? To me it sounds like too much gas rather than obstruction or lack of gas. When you remove the fuel filter it flows stronger, thus causing the fuel to exit via the overflow tube.

 

i would pull the float bowl and clean the needle and seat, you have something stuck in the needle, the filter wont fill all the way up,i think you are just flooded out thats why it wont start maybe go get a new set of plugs after you clean the carb

 

Wow, I never would have thought it was getting too much gas (I'm very new at this). I do smell fuel when the engine turns over, but I wouldn't say it's raw gasoline. The spark plugs are coated with black soot and I cleaned them off when I checked that they were sparking. I will check that out when I get back in town and update the thread. Thank you guys!

A couple of clarifying questions, so I can rationalize what's going on -

1 - If the float bowl is in the carb, then why is the filter not filling up with fuel?
2 - If it's a symptom of too much fuel, why aren't the spark plugs getting wet and the engine flooding?

 

If it helps, here is a picture that I took while everything was working:

http://www.flickr.com/photos/67696148@N04/6374156155/http://www.flickr.com/photos/67696148@N04/6374156155/ by http://www.flickr.com/people/67696148@N04/, on Flickr

 

sorry double posted again!

 

wow i really dont like the way that fuel line is ran,(may be ok when you have a full tank) but you cant have that big *** loop under the carb, as far as the filter goes it wont fill up if the fuel is goin right thru the carb ,when the carb is working right the filter still wont fill up, i would think that there i no way for the filter to vent air , mine is never more than 2/3rds full at any time, i hope this makes sense i still say if you puting fuel out on the floor you have a needle problem,no offence but i do not know much about the s&s carbs other than i use them for paper weights and trading stock lol

 

The fuel line should be OK routed like that - i have seen lots done that way. Not pretty but it works as long as it is below the tank.

The external fuel filter will not usually be completely full and this too is not a problem.

There may be a problem if there are two fuel filters. Run either the one that is attached to the petcock in the tank or the external filter, but not both.

You should not smell fuel while the engine is turning over.

Time to uninstall the carb and do a cleanup. Here are some notes; these are written for a Keihin so while the details are different the process is the same ...

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.

 

i have been runing the filter in the petcock and a in line filter in all 3 of my ironheads and all carb combinations for many years never had a fuel problem, clean the carb and you will be fine

 

Thanks a lot guys - while I do this I want to make sure I understand the problem and not just fix it. I do see a filter on the petcock as well, so I am running 2 filters, but my gas tank is pretty nasty inside. I guess when I clean the carb out my next step is to clean the tank out too.

I'm not a big fan of the S&S, but that's what was on it when I got it so I'll have to make due for now.