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You're an evildoer.
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Discussion Starter · #1 ·
Long one guys...sorry I just want to give as much detail as possible.

I've run out of ideas on what the heck is going on here and would love some ideas on things to check next.

PROBLEM:

For no obvious reason the bike will foul both plugs out and it always seems to be on the way to work (Soot, black, dry) which is only 25 miles, at 40-50MPH with a few stop lights. No, The Choke is not on :whistle:

What I have:

'96 1340 EVO in a Fat Boy Stock CV Carb modifed with a 180 jet (stock was 170), Dynojet kit I think was used when the previous owner did the upgrades, 42 slow jet (Stock I beleive), clip on 4th ring, 3 washers above this. Has a Stage one breather and Phyton III pipes. It also has a SE Cam, but I dont know what the number is on it. Plugs only had 1000 miles on them, stock ones from HD. The idle mixture is currently 2 1/4 turns out, which I would think is lean.

STARTING PROCEDURE:

Pull the choke, start it, push choke in after about 20-30 seconds, and drive off keeping it under 2k RPM for about 5 miles.

How I am riding

Cruising, 4th or 5th gear - nothing heavy, minimal stop and go, just cruising along happy until I notice in the 1500rpm rage a little misfire, which then gets worse and worse and worse.

Needless to say, the bike ran fine for 4000 miles, had no drivability issues unless I was a dork and left the choke on one time but I learned my lesson on that. About a month ago, on the way into work, the bike started to foul up (had been running fine for 4 months). I figured it was the battery getting old, so I pulled over, put in a spare set of Champion plugs and finished my ride in. I gapped them to .040. The plugs are 404, whatever they say on Nightrider is the equivalent.

That evening I put in the new battery (The old one was almost 5 years old), and the next morning, the same thing happened. Pulled over, put in a new set of plugs. Finished my ride in. On the way home, had to pull over and put in another two plugs to get it home.

So now I am having plugs foul and did the following to TRY and resolve this issue:

Recharged the K&N filter, which didnt look dirty anyway.
Replaced the coil with a known good.
Replaced plug wires.
Verified the diaphram was good.
Verified idle was 950-1000.
Verified idle/trottle cables were adjusted right.
Verified the float was good and replaced the float needle.
Replaced gaskets up to the intake, but not the ones on the sides of the jugs. I did test for leaks with propane and couldnt find any (Its not running lean).
Drained tank, checked for debris, checked the filter, all seems ok - its getting gas.
Checked the enrichier cable, its working right.
Cleaned the carb, making sure nothing was clogged up.
Adjusted the Idle Mixture
Checked the charging system.
Checked for corroded connections in ignition system.
Replaced plugs countless times.

NONE OF THIS HAS HELPED! :hmmm:

The odd part - I've driven the thing for 500 miles for the same length of time, following the same path to work and had no issues at all and the next morning it goes crazy. I've driven in 20 degree weather to the dealership for new tires a week ago, then put 300 miles on them and not a single problem. This morning - it pukes out.

So, ideas on where to look next? I was going to check the VOES, timing and double check the vac lines and tank vent.

I can drive the bike for 45 minutes cruising at 40-60 with no troubles at all for 3-4 days.

Is it humidity? Is it just too cold? Should that really matter 30 minutes after going down the road?

This morning, 20 minutes after no traffic steady driving at 45 MPH needed to put in new plugs, 20 minutes later, it was fouled up again and I turned around and went home. I am in Chattanoooga, weather this morning was 30 degrees, humidity was 88%, It was a nice cool morning.
 

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This is just my opinion..don't take it as gospel...I'm not a big fan of Champion plugs..I'de go back to Harley plugs..they might be made by Champion but I think it's a better quality..also I'de put 2-3 ozs of Marvel Mystery oil in the fuel every other fill up.....
 

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could be a weak coil too. get one of your friends to let you try their coil and see if this clears it up.1500 rpm is lugging the motor,2000 is even slow,let it rev alittle.
 

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Discussion Starter · #4 ·
Coil was replaced with a known good, was actually the second thing I did after the battery was replaced. One thing I learned working on airplanes in the military, find something you know works - its alot easier and cheaper.
 

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Try a #45 idle jet and a #175 main. As for the needle, move it {the needle} down a notch at a time until you get consistant lean cough/split {with a warmed up ENGINE}, then move the needle up one notch. :chopper:
Verify the float level is where it shoud be. -2$en#e-
 

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I'm gonna powder his nose
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Make sure that the choke plunger is returning to the open position. (you will need to remove the carb to check this)

This is the ONLY variable (aside from ambient temperatures) that you do to the carburetor from day to day, the jet settings remain the same so if it runs fine most of the time it's NOT the jet settings.

Sometimes the choke plunger will stock open (especially with the poor choke cable routing on the fat boy) even though the choke knob is pushed in thus causing a rich condition and fouling the plugs.

I personally go through plug wires and plugs allot (every 3 races) and have isolated the chrome coil cover from the coil and it's wires to prevent shorting out or robbing the spark, I also isolated the plug wires to the cylinders from anything metal to retain good spark.

Hope this helps.
 

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Discussion Starter · #7 · (Edited)
Got home from work, put in the HD plugs that had fouled up when the battery was low a month ago (I actually marked them and saved them). They cleaned up rather easy and I verified gap was ok.

Drove the exact same way I drove this morning, including the twisties and leans just in case float or something odd is off.

Not a single damn problem. So I turned around at work, drove almost home and stopped to fill up on gas - still no problem (Coming home was stop and go traffic like normal).

Pulled plugs they looked like they did when I put them in.

The only two differences are it was 27 degrees warmer, and the HD plugs. I think these are the 2.95 plugs, not even the gold.

Im going to try again in the morning, and see what happens. This all started when my battery started to take a crap and I changed the plugs after the battery didnt fix it. This always happens in the morning and has happened once in the afternoon.

If it works for a couple of drives in, I'll chock this up to 16 bad spark plugs over a month. I just find it very hard to beleive that plugs from Champion (who makes the HD plugs) which are RN12YC (I "think") could cause this for me. I have no qualms with buying these plugs I just figured it was the harley tax, nothing more.

On a related note, I verified the turns on the idle mixture, and with the engine running, warmed up, after my long drive - with it closed it didnt stall (yeah it ran a little rough). I would have expected it to completely crap out. Can that screw be removed to inspect that area for obstructions, and stuff?
 

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Discussion Starter · #8 ·
I also plan to check the choke cable in a bit, it MIGHT be binding, but I doubt it - when the choke is pulled on this bike, I cant go more then a few blocks before it sounds like the 4th of July.

Any tips on this one, I dont recall the service manual helping alot here.
 

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do you have a vacuum operated petcock? if so, fuel may at times seep past the diaphram and into the vacuum line.
 

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Discussion Starter · #10 ·
Interesting find, I was looking at the petcock (vacuum, its also recalled I think), and when checking its operation just now, when its in reserve, it leaks.

Since I 1. Never ran out of gas, and 2. never turn it off cause I'm lazy like that and knew it was vacuum operatred, I've never put it in reserve.

Regardless if its the problem, a leaking valve is bad.
 

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next question, ws your jetting done with a bad petcock? if so you will need to correct that also.
 

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Discussion Starter · #12 ·
Ok, The leak was not the petcock, it was the Mity-Vac hose dripping a little (a clear one from the kit I was testing the flow out with, not the one vacuum is applied to). I couldnt make it leak once I had the fuel line back on so I repeated the test and realized when I spun the valve to reserve the line moved.

I pulled the enrichier cable off the bracket and it was, in my opinion, twisted or cockeyed a little bit because when it came down, it also spun some (about half a turn maybe). Adjusted it and reinstalled it.

I dont want to change anything else for a few days, and the weather is looking crappy so when I can do a few early morning tests this week I will. May be able to sneak one in tommorow and leave work around lunch time. (Thunderstorms for a day or two).

Thanks for the ideas, it could have been the choke binding, and I created the problem myself back when the battery was bad and I just put in a bad plug. Thats the hardest part of working on things, you introduce variables yourself which can very well cause the problem.
 

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I used to have some plug fouling problems ('95 Fatboy) as well. My mechanic advised me to NEVER use the choke - never have had a problem since. Just crack the throttle open a tad and goose it a little for a minute or two before you ride off. You'll find that the choke was never necessary (just convenient) - and - I bet it is the source of your problems.
 

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tibs, I'm running a 44mm SE CV on a '96 80" and have never had a single problem with Autolite 4265's. A Champion in my bike just will not live very long at all.
 

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90 FXRS LOWRIDER
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champion plugs are good for one thing........lawnmowers. and i don't recall seeing any of us ridin those down the highways!
 

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re:plug fouling

Just as Ohiomotoxer state's it can only be in you enrichment system acts like your plunger is not seating (may need a new one if it is scored bad)especially since you can turn in you air mixture screw without the bike stalling. Good luck:Banadance
 

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Discussion Starter · #17 ·
I havent tried the screw since I checked the cable but I will.

I park the bike in my garage which never gets below 60s, so yeah I can start it without the enrichier. Its the 20 degrees at work thats going to make it a bit of a problem for me, I can always try though.

I'll pull the carb off and remove the cable and see how it looks.
 

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tibs said:
I also plan to check the choke cable in a bit, it MIGHT be binding, but I doubt it - when the choke is pulled on this bike, I cant go more then a few blocks before it sounds like the 4th of July.

Any tips on this one, I dont recall the service manual helping alot here.
open the friction nut and pull the knob out and push it back in. You should feel free play (about 1/10") when you pull the know slightly. If that works out, tighten friction nut and you are good to go. If not, take off carb and disassemble enrichener, clean the valve and check cable for binding. If there's a problem, replace the cable. Once the carb is off, a good cleaning maybe in order
 

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All good advice, but (as I said) treating the symptom not the disease.

Read this: http://www.rmh-d.com/service/enrichener.php

It's best to forget that that knob is even on your bike. Before you start dissecting your HD, change the plugs and forgo the choke for a few weeks. Your problem will be gone forever. I live in a colder climate than you do and I never use the choke.
 

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RickinColorado said:
All good advice, but (as I said) treating the symptom not the disease.

Read this: http://www.rmh-d.com/service/enrichener.php

It's best to forget that that knob is even on your bike. Before you start dissecting your HD, change the plugs and forgo the choke for a few weeks. Your problem will be gone forever. I live in a colder climate than you do and I never use the choke.
What he said
 
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