Fouling plugs

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dave51fl
Posts: 11
Joined: Fri Jul 13, 2007 8:56 pm

Fouling plugs

#1

Post by dave51fl » Sun Nov 12, 2006 9:54 pm

Hi Guys,

I was wondering if anyone could help me with the following problem. I’ve just finished putting my Pan together and been out for a couple of runs and I can’t seem to get anymore than about 50 miles out of it before the plugs foul.

The low idle jet is set properly, the float level is set properly, and the fixed high speed jet has number 17 stamped on it which is correct as per Palmers book. Regardless of how far down I screw the fixed jet trimmer the bike runs exactly the same.

Any help would be much appreciated.

Thanks

Dave



panhead
Site Admin
Posts: 2471
Joined: Wed Dec 12, 2001 9:17 pm
Bikes: 1954 FL
Location: Holland

Re: Fouling plugs

#2

Post by panhead » Sun Nov 12, 2006 10:46 pm

Have you used new plugs?

Cotten
Posts: 6791
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: Fouling plugs

#3

Post by Cotten » Sun Nov 12, 2006 11:06 pm

First, let us check out all of the possible things it could be that are not carburetion:

Are you by any chance running resistor plugs or wires with a conventional points ignition?

Timing and valve adjustment have been double-checked dead-on?

Is the battery keeping a charge?

And of course, a manifold pressuretest is mandatory, or you might just chase your tail. Better snoop the headgaskets and plugs while you are at it.

After those considerations:
Are both plugs exactly the same?
Can you see fouling? Does it extend deep into the insulator?
Do they appear wet or dry? If wet, do they dry out quickly under a heatlamp or hotair gun, or stay greasy?

If they are not oiled, and all of the above conditions are inspected, then we can address the carb.

...Cotten

keys55
Posts: 29
Joined: Sat Jul 14, 2007 8:51 pm

Re: Fouling plugs

#4

Post by keys55 » Mon Nov 13, 2006 12:55 am

I was wondering what brand of plugs you use. I was wondering if any of the members had a favorite, through trial and error.I know they are all not created equal. [copper, copper plus, platinum,splitfire, u groove, fine wire, etc.]

caschnd1
Posts: 589
Joined: Tue Apr 25, 2006 3:45 pm
Bikes: 1949 FL Chopper

Re: Fouling plugs

#5

Post by caschnd1 » Mon Nov 13, 2006 3:12 am

I simply use plain old Autolite plugs. Nothing fancy. No split electrodes, no platinum. Replace them every year or about 10,000 miles.

-Craig

Tricky

Re: Fouling plugs

#6

Post by Tricky » Mon Nov 13, 2006 7:57 am

On the needle assembly there is the needle, spring, adjuster screw and screw to keep it all together. I once made the mistake of fitting the spring over the needle, rather than behind the needle....this meant the needle was never close to its correct position. Amazingly it ran, and gave the symptoms you talk of.....just a thought.

dave51fl
Posts: 11
Joined: Fri Jul 13, 2007 8:56 pm

Re: Fouling plugs

#7

Post by dave51fl » Mon Nov 13, 2006 10:03 pm

Hi All,

Thanks for your quick response. I'll try and answer the questions as I go.

Panhead & Keys55 - I've put several new sets of plugs in and all different brands.

Cotten - I have a repro coil on the bike and I'm using the leads that came with the. I've checked these with my local harley expert and he thinks they are OK. His website if your interested is http://www.hddev.com.au

I will double check the timing but it seems OK.

Its a brand new battery with a rebuilt generator and that seems to be OK.

I will double check the manifold.

Both plugs are the same and it seems to extend down into the insulator.

When you take them out they appear damp but dry out very quickly when out of the bike. Once dry if you wipe them with a cloth they clean up.

Doing some more research last night it says early 51's had a #17 jet and later 51's had a #19. Would this make a huge difference?

I didn't mention in my first post that it starts well; idles well and goes well. Until we get to 50 miles and then it starts missing and it ends in tear.

Thanks again gents.

Dave

jellero
Ex-member
Posts: 131
Joined: Tue May 23, 2006 1:25 pm

Re: Fouling plugs

#8

Post by jellero » Tue Nov 14, 2006 12:47 am

you didn't mention where you are, like elevation? i am at 7,000' and had a #19 (#45 drill size, .082"). i could get 50-60 miles before fouling out. i worked my way down by taking out main jet, soldering it and re-drilling four times in steps, ending up with a drill size #54, .055". plug looks right, bike runs great. i used to get a black smoke when revving engine and pipes were black. i also bent float down 1/8" because the 1/4" figure is for a cork float and i have a brass float, much heavier. i also had the high speed trimmer all the way in, meaning too rich, can't be adjusted here. after re-jetting the final time, i took bike out and it wouldn't go over 30 mph until i backed out the trimmer and it took off just like twisting the throttle. j

Sidecar
Posts: 248
Joined: Tue Apr 17, 2007 9:21 pm
Location: Southwestern, Pa.

Re: Fouling plugs

#9

Post by Sidecar » Tue Nov 14, 2006 2:02 pm

"Until we get to 50 miles and then it starts missing and it ends in tear."

Your coil is bad !!!

I had two of these Repro coils do this EXACT SAME THING to me.
After the third one died I went to a round canister style one with no problems. Later I changed to electronic ignition and had to take the canister coil off and get a Dyna coil.

jellero
Ex-member
Posts: 131
Joined: Tue May 23, 2006 1:25 pm

Re: Fouling plugs

#10

Post by jellero » Tue Nov 14, 2006 10:25 pm

if the bike will even run one mile with the trimmer turned in all the way tells me it is jetted too rich. it isn't even using the high speed jet. plus the black gas fouled plugs... where do you live dave51?? j

dave51fl
Posts: 11
Joined: Fri Jul 13, 2007 8:56 pm

Re: Fouling plugs

#11

Post by dave51fl » Wed Nov 15, 2006 2:12 am

Hi Jellero,

I live in Melbourne, Australia so i don't think altitude is an issue.

I think you're right that jetting is an issue so I'll replace the float and get a smaller jet and see what happens.

Cheers

Dave

Cotten
Posts: 6791
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: Fouling plugs

#12

Post by Cotten » Wed Nov 15, 2006 2:30 am

Dave!

What float are you running?
If it is an original and your fuel has not soaked it, it should be serviceable at book spec.
I used to weigh them, then place them under the hot sun or a heatlamp for a while, and then weigh them again. If there is no change, your float is fine.

(That's assumeing your fuels are not digestive like in the USA!)

Changing the jet is an option, but please only change one variable at a time.

By "Until we get to 50 miles and then it starts missing", do you mean 50 miles distance, or up to 50 MPH?



....Cotten

jellero
Ex-member
Posts: 131
Joined: Tue May 23, 2006 1:25 pm

Re: Fouling plugs

#13

Post by jellero » Wed Nov 15, 2006 2:55 am

melbourne... got me there. do jets wear? get some numbered bits and measure it? i didn't find any jets available that were much leaner, that's why i filled & drilled mine. but like cotten said, you don't want to go too far at one time.
hey, maybe the high speed needle/seal is bent or worn letting fuel through?? have you pulled the needle? that would be an easy fix and make some sense. good luck, j

stevo

Re: Fouling plugs

#14

Post by stevo » Wed Nov 15, 2006 5:11 pm

I was not told resistor plugs bad in points distributor panhead??
Oh Oh.

dave51fl
Posts: 11
Joined: Fri Jul 13, 2007 8:56 pm

Re: Fouling plugs

#15

Post by dave51fl » Wed Nov 15, 2006 10:01 pm

Hi Guys

Once again i really appreciate your help.

Cotten
The float is a brass float and I've left in petrol overnight and it hasn't sunk or sprung a leak so it seems OK.

Your suggestion of one variable at a time is a great idea and I'll start with the jet and see what happens.

The 50 miles is in distance and doesn't really seem to matter if its round town or highway work.

Jellero
Melbourne is the second largest city in Australia behind Sydney. That another good point you've mentioned which I'll investigate while the carbie is apart.

I've just stuck a picture of her on the site so you can have a look.

Cheers
Dave

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