F head fouling plugs quickly

As many of you know I just bought a 55' with an f head. The plugs were fouled last night pretty bad (first time I have started it) I replaced the plugs last night and today they are pretty sooty again. I have never owned an f head, so this engine is new to me. I have replaced the oil filter cartridge, cap, rotor, plugs, fresh gas. The coil states "no ext regulator needed" so i assume the correct coil is in there. The motor itself sounds very very quite with no ticks, clicks, knocks, etc I was actually very amazed. however there is some sputtering from the exhaust. The choke is opening all the way, and I have not yet checked timing. any ideas?? The plugs after just 15-20 mins of idling and a quick 5 sec run up the road are already black again. not oily, just real sooty

 

Did you get a chance to see if the coil is correct yet, This can contribute to the sooty plugs.

Lets see, Oil bath air cleaner serviced and oil level in cup correct? an overfilled cup is equivalent to having the choke partially on.

When you serviced the air cleaner did you remove it from the firewall, and when the cup was off turn it over and look between the inner and outer housings and make sure oily dirt has not built up between the two housings under all the little round intake holes, effectively restricting or possibly choking off completely the air intake. This condition is quite common on neglected oil baths.

 

Brian, the coil states "external regulator not needed" so i assume i am good there. as far as the oil bath filter goes, it was really sludgy in the botom and the upper can is soaking in kerosene right now. will aggitate it tomorrow the best i can. Could a really dirty oil bath filter be causing this??? I did drive it back int he agrage with no oil bath filter on at all and it still sputtered, but the plugs were already fouled so that might be why.

 

Hmmm.......Float level to high?, Pump diaphragm starting to leak under high manifold vacuum? If this rig sat for a long time ..........especially without being run the pump diaphragm could be partially dried up and leaking. I would consider the diaphragm a good suspect if the air cleaner is known to be completely clear.

Based on the slight blubber at idle and the sooty plugs I would recommend,

1 double ck air cleaner, 2 replace pump diaphragm, 3 double check coil for correct application.

 

Sounds like the coil is ok and the air cleaner will be clean..........you may need to make a small metal scraper to get between the inner and outer housings to get all the oily cacked on dirt out if its been neglected.

I would head straight for the pump diaphragm in the carb based on your symptoms. When they leak it will let fuel directly into the intake manifold below the throttle plates as the bottom of the diaphragm is directly exposed to manifold vacuum.

And yes, a very dirty neglected oil bath air cleaner can cause/ be a major contributor to this.

 

My local NAPA carries the pump diaphragm as a separate component, its an Echlin 2-4218. I have had good luck with those diaphragms, they are supple and seem to last reasonably well.

 

the oil filter was very nasty and i did not clean it before i ran the new plugs, could the nasty filter have caused this issue???

 

A dirty oil filter should not contribute to the dry sooty plugs

 

Brian i think my lack of wording has confused myself or you. The oil filter is fine, the oil bath air filter was very nasty when i took it apart today. This was After I had already fouled the new plugs. I do know the carb was rebuilt a couple years ago due to me finding reciepts the PO had in the tool box. However, it had sat for about 6-9 months before now. Maybe a rebuild of the carb is in order or just replace what you have said. Either way the motor seems to run great, just wish i could get things smoothed out. I do not have a tach for this so i need to get one to set timing at 600 rpm. Thanks again brian you have been a huge help

 

Good points, I assumed timing was checked but did not ask.

 

patrick, the compression seemed good, but i think my meter is acting up right now, i think it is leaking by around the hose and one of the connections. Dwell is something i have never had to check due to always running an upgraded ignition. I have a new condensor and points i just have not installed them yet, a little hesitant on doing new things (I know you never learn until you try) timing might be off, she seems to be idling higher than 600 rpm per the fsm. i need to get a tach and then check that out.

 

After you give Patrick's comments consideration, I have noticed that there is nothing you can do to smooth an F-Head out once the diaphragm starts leaking ( assuming everything else is known to be ok ), mysterious on and off rough idling thatyou cant keep adjusted is one of the symptoms.........I keep a spare on hand and an extra with me in my "trail kit"

 

Just for peace of mind, a carb rebuild kit is under twenty bucks, and not hard to do. It would seem like a good investment, for you to know that everything is ship shape. No telling if the previous owner did it right.

An F-head I just got had a half inch of sludge and corrosion in the float bowl. I got a kit from Krage and got everything clean and adjusted. Now it starts and idles like new even at zero degrees.

 

Dry black plugs mean the engine is running too rich, like the choke is closed constantly. If it were oil, the plugs would be tarry not dry. "Fouling" typically means oil-fouled, and the fouling causes the plugs to not fire. The engine runs ok when you first put the clean plugs in, but as it runs more, it starts misfiring.

I'd look at the fuel system first - adjust the carb, look inside, rebuild, new carb, whatever it needs.

A compression tester is $10 at Harbor Freight, IIRC.

 

thanks tim, i already ordered the rebuild kit. I assume these are just as easy as the stock 2 barrells on the dauntless? All i need is a new fitting for the end of my tester.

 

Also, on an engine where the history is unknown and isn't running right, I'd go ahead and replace the cap, rotor, wires and plugs. Keep the originals for spares, if they look ok. Pull a plug wire and check the spark color. It should be blue-white and jump at least a 1/4" gap. If you don't know how to keep from shocking yourself while doing this, ask. A coil is a good spare to have, if you want to replace that too.

You are going to have to change the points eventually ... a dwell meter is handy http://www.amazon.com/Actron-CP7605..._1?ie=UTF8&s=automotive&qid=1234618017&sr=8-1 - I don't have this one, but I have something similarly cheap and it's worked fine for decades.

You could instead put in the Pertronix kit now, and skip the points altogether. You'll still need to set the timing and idle speed though.

I'll let the F-head guys answer questions about rebuilding the F134 YF. I presume so - apparently there's a lot of difference in the brand of kit. If you search you'll find some discussion about which kit to get.

 

The YF is an easy carb to work on..........The F-Heads are waiting :twisted:

 

Again, thanks this is a whole new animal to me. I have the new points just no clue what I am doing. Just gonna take ny time, this is getting stripped down anyway
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