87 FLH Sport,,,with 96" S&S motor,,,,,runs great but lately it will just die while riding,,i pull over and it starts right back up,,not losing any electric,,no warning light on dash till oil pressure falls ......all lights and stereo stay on just lose motor ...i checked coil resistance and it's 10800 which is great,the ignition is compu-fire elite 1 ,,i went back to dual fire a couple months ago when i had to change coils and i had a dual
fire on the bench,but coil is testing good and none of the wires are crispy,,please help i'm riding to the beach in 3 weeks,and i'd like to figure this out before i go,,any help much appreciated
I had the exact same issue on my 111. These big inch motor do not like dual fire. I switched to a single fire and problem solved
A break in the white wire that gives power to the coil?
I would wiggle the wires around, check near tie wraps as well.
Why did you change coils- that sounds suspiciously like your ignition is going bad?
everytime the bike got washed ,it wouldn't start,,,,,,so i got a spray bottle,and wet the coil to check,and that was it,,,,and i just had the other coil as an extra for my shovel sittin there so i used it,,and changed the setting on ignition to dual fire and it was fixed,,,,,it ran a lot harder with the single fire ...but its still fast
i pulles the tank to get to the coil,the wires look great connectors solid,,but i also pulled the petcock,and it looked like a lot of "Potty mouth" on the screen,,,got a new 45 a couple months ago and was putting rounds thru it,,and a bullit ricocheted into the garage,and hit the tank of my FLHS,,so i had to get a used tank off EBAY,,and it wasn't as clean as i thought
Part of that post helps.
I don't know where to go with the last part.
Check the insulation on the ignition wire coming out of the back of the nosecone for short to ground
Quote from: Hossamania on June 14, 2020, 06:39:56 PM
Part of that post helps.
I don't know where to go with the last part.
:hyst: yep
Quote from: misfitJason on June 14, 2020, 05:15:21 PM
I had the exact same issue on my 111. These big inch motor do not like dual fire. I switched to a single fire and problem solved
Never heard nuthin like that!!!
New twin tech kit,ign,coils and wires are well worth the money,it will serve you well. Fore a long time.
could the float be set too low and the carb bowl run out of gas at higher speeds?
Quote from: Racepres on June 15, 2020, 05:24:33 AM
Quote from: misfitJason on June 14, 2020, 05:15:21 PM
I had the exact same issue on my 111. These big inch motor do not like dual fire. I switched to a single fire and problem solved
Never heard nuthin like that!!!
I know right! I chased everything. Talked with the boys over at Daytona Twin Tec and in about ten seconds they told me what he problem was. Apparently the wasted spark on large displacement motors has a tendency when the conditions are right to ignite what's left in the fill area and spit back through the Carb. It was very intermittent and only at decel and idle. Changed to single fire and fixed the problem immediately
Quote from: misfitJason on June 17, 2020, 08:26:34 AM
Quote from: Racepres on June 15, 2020, 05:24:33 AM
Quote from: misfitJason on June 14, 2020, 05:15:21 PM
I had the exact same issue on my 111. These big inch motor do not like dual fire. I switched to a single fire and problem solved
Never heard nuthin like that!!!
I know right! I chased everything. Talked with the boys over at Daytona Twin Tec and in about ten seconds they told me what he problem was. Apparently the wasted spark on large displacement motors has a tendency when the conditions are right to ignite what's left in the fill area and spit back through the Carb. It was very intermittent and only at decel and idle. Changed to single fire and fixed the problem immediately
Very Odd indeed... must be the Cam they are Using...I have a 114 cubic inch Sportster...and it runs just Fine on DualFire..Depending on Fuel/Timing/Compression...
During a discussion in another forum one time, I went through the whole timing calculations thing and without doubt, if there is enough BTDC timing on the intake cam lobe (rear I believe), with dual fire the plug is firing while the intake valve is open. On tame cams, probably not an issue. With hot cams, it is possible there is enough exhaust scavenge to pull some intake charge into the cylinder when the wasted spark fires, igniting what's in the intake manifold. And I don't think that is specific to big inch motors, a stock displacement motor with a hot cam would have the same concern.
-JW
I think guys over analyze and read too deep between the lines around this.
I'm not going to say it doesn't happen, but I will say it is highly unlikely. And in 40 years of dicking around with HDs I have never seen such.
But I have heard many who claim they can feel a difference between single and dual fire, which I also feel is a :turd: steaming pile of conjecture.
My bet is they are feeling a properly tuned motor, not the difference between single and dual fire.
I have a huge amount of experience in this area on many different types of motors and have never seen any negative affects from either single or dual fire.
The big advantage of single fire is the ability to time the rear cylinder separately to make up for mechanical differences between the front and rear cylinders.
So the rear cylinder can be as dialed in as the front to eeek out that last iota of power for a dyno shootout, or tuning a boosted motor set on kill.
Another advantage of single fire is that the coil has more dwell time available, but HD motors don't spin high enough RPM to really see a benefit from that aspect.
For street use I don't recommend tuning on kill, its an air(oil) cooled motor and there are too many variables in pump gas to run a street bike that close to the edge.
And that is a real edge, with gas you are dancing on a razors edge between max power and detonation.
I'll accept slightly less power for consistent performance and longevity of my pistons.....
My original standard 1987 pistons in my 100k mile FXR will attest to this tuning theory.
Not many guys who ride as hard as I do can say they are still running their original pistons!
Quote from: Burnout on June 18, 2020, 09:32:15 AM
But I have heard many who claim they can feel a difference between single and dual fire, which I also feel is a :turd: steaming pile of conjecture.
My bet is they are feeling a properly tuned motor, not the difference between single and dual fire.
I've never been able to tell a difference I could feel after a single fire installation. Maybe a could dyno could have measured something before vs after; but nothing I could measure via the seat of my pants. What I have noticed, however, is times when the bike started better after a single fire install. Nothing else changed. Just the ignition system. Some times when the bike did obviously start a little easier.
Personally I don't think there is any noticeable difference either between single and dual fire. My earlier post was just an engineering geek exercise to confirm that on paper, with dual fire you get a spark event with an open intake valve. That is fact. I didn't say, nor believe, it makes any difference in the way the motor runs. That said, if I have a bike with an ignition module that has single fire mode, I ALWAYS set it to single fire. Why? Makes a hell of a lot easier to see the timing marks on the flywheel with a strobe light!!
-JW
Tech talk aside on this, the subject line creeps me out every time I see it.
The preferrable going in Ponderosa horseriding times, was with the boots on, wasn't it? :hyst:
Agree, Hoss. Not the most tasteful subject line I've ever seen either.
-JW
Quote from: Hossamania on June 18, 2020, 11:30:29 AM
Tech talk aside on this, the subject line creeps me out every time I see it.
Me as well. Lost a friend last week. Ran off the road and hit a pole. Coroner said Cardiac event and was probably gone before he ran off the road
Do you have any access to an Oscilloscope to view the Secondary Ignition Wave Form? That would eliminate the Coil, Wires, and Plugs - Just blip the throttle a few goo times.
"Personally" I would look to fuel delivery first. Solid State Parts do go Tits Up, but not as often as one would think in my experience. In fact, if it is electronic, i would bet the Signal Wire is where the issue will lye and not the Coil if it within specs.
I like subject lines as this - Get's attention for your post. JMO
I'm a the Pirsch, check fuel delivery. Have you checked the gas cap for proper venting (one way, in)? What type of petcock, has the screen been checked? Also as mentioned, has the float level been checked?
Does the bike have the fuel vent check valve? It's a valve that locks vapors in the tank but lets air displace fuel used. The fuel cap does this but I have found at times the cap isn't enough. I had a bike go through a flood and mud blocked the valve rendering it useless also had a spider build a nest in off season causing a blockage. Try running without the cap.
In regards to dual fire/single fire. I prefer to use single fire. I feel it keeps the harley "cough" to a minimum and it cuts down on vibration.
I serviced a 124 build with big cam and compression. It came originally with DynaS dual fire. Another shop in their infinite wisdom replaced it with a non Dyna single fire. It ran like crap. I spoke with the original builder and reinstalled the D/F Dyna s and never looked back.
MIKE