Help with engine miss.

[k9nut]

Sorry about the long post. I have posted this problem before but have not found a solution yet. I was hoping some of you could make a suggestion as to the problem.

I have been having an intermittent engine miss since last June. The bike runs great when it is cold. After warming up the exhaust note will start to change to a slight “popping” note at a constant RPM say 70 MPH. After two to three minutes of this the engine will lay down in power and start a “motor boating” sound. If the throttle is opened at this time the engine will pop through the air cleaner a couple of times and then start backfiring very loudly through the exhaust. The engine will also start surging at a constant throttle position. After stopping the bike the engine will idle OK and at this point and I can slowly start moving until just over 2000 RPM and then the engine will lose power and resume backfiring and surging. The engine will not go over 2500 RPM If I continue on the throttle at this point the engine will quit. In June I was able to ride 100 miles or so before the problem occurred. In Oct I was able get to Las Vegas (300+miles) before the problem started. The ride times before having the problem have been getting shorter each time. The last five or six rides I have only been able to ride about 30 miles before the problem occurs. Sometimes the problem will clear after a couple of miles and run fine for a few miles and then start again. Other times I have to shut the bike off for 45 – 60 minutes and then it runs fine for another 40 or so miles.

I have had the bike at 2 different Big Dog Dealers, 1 Big Dog Service center, 1 independent Harley shop and 1 local Chopper shop for a total of 18 weeks and $2500. None have fixed or found the problem. One said it was probably a fuel problem, another thought it was ignition and one said a valve sticking problem. The only thing we all agree on is it is heat related and is not spark plugs. I have one more BDM Dealer to try, Before that I was hoping to get some ideas from this group so I could have a “check list” to at least make sure everything is checked. If I knew the problem I would probably try fixing it my self. Most of the basic stuff like leaks, dirty gas, dirty filters etc have been done so I will not list all that stuff here.

I really do not know where to go with this. Perhaps tear it down and sell the parts on eBay. (Joke)

Thank you for any ideas you can give me. – Gary C

 

[N8KAM]

I looked at your other threads and found no mention of what has been done so far. so to keep from going in the wrong direction can you tell us what these 3 shops have done??
Sounds like a fuel starvation problem the way you describe it. Have you tried removing the check valve from the gas cap (if equipped) and then going for a ride??

 

[beast30]

Yeah a list of stuff the shops did would give a starting point for sure. I wonder if the Igniton Coil is heating up.

Sorta sounds like the problem I had last year with the ignition sensor. Would run fine then just quit or backfire and quit. Let it sit for 10 min or so and fire back up. The Nice thing is that they are fairly inexpensive I think mine was like 50 bucks from J&P. Not sure how to test it thou.

 

[Gas Man]

Yeah I think these boys are right...

Keep it simple first

Gas cap
jets
nozzle clogged
battery cables both tight and cable secure to the terminal
terminal connecting power to the ehc
coil

 

[k9nut]

Thanks n8kam: Yes I have even taken the gas cap off when it was missing and that did not fix the problem.

I have taken the gas tank off and flushed it, removed the shut off valve and cleaned the screen, changed the fuel line, cleaned the carb. I have checked the gas cap and the vent line. I have checked the intake manifold for leaks. I replaced the gas with new from the pump. The plugs have been replaced 4 times by me, the plug wires have been replaced. The electronic covers have been removed and all electrical plugs have been checked, dielectric greased and heat shrunk. The greasing and heat wrap I originally done at about 1000 miles so I removed and redid. That includes the connectors under the tank. The jetting was done when the exhaust was changed at 700 miles and has not been changed and the bike has +15K miles. The exhaust gaskets have been replaced and ports checked for carbon buildup. I have checked all nut and bolts for corrosion, checked battery connections, installed ground wires from the ignition module and EHC. Used my manual wiring diagram to trace all wires in the ignition circuit to make sure they were all checked, I have cleaned the crank sensor.

At this point I started taking it to professionals for help. I am not sure exactly what they all did but I know the carb was removed and checked, cleaned and manifold gaskets were replaced. They all changed spark plugs and they "read" good after test rides. I am sure the Big Dog Dealers hooked up the ignition module to the diagnostic program. The compression was checked. They all did a visual to the wiring etc. One of them did remove the gas tank to chech the screen. They all did the carb adjustments.

I did this list quickly so may have missed something. I hope this helps you think of something none of us have thought about. - Gary C

 

[Gas Man]

I would think it lies in the ignition and coil then.

Ever consider doing an overhaul on those. They're a worth while change anyway. You could probably change those both out yourself for the same price of paying some dealership to scratch their heads over the bike.

 

[REMorris]

I agree that it sounds like fuel starvation. Classic symptoms are max rpm and the motorboating sound.

You are getting enough fuel to make it up to a certain speed, and then your supply equals the demand.

This also jives with your cold performance being better. You simply haven't run it out of the fuel bowl yet. Probably within a block you will b noticing the problem.

So, my guess is the problem is somewhere in the float valve (in the carb) to the shutoff valve (in the tank). Personally, I would take the shutoff valve off and disassemble it, (or if you can shine a light through it, no need to disassemble it). Put a new hose from it to the carb. Last, pull the carb off and start looking for obstructions.

Richard

 

[lee]

see if you can borrow a known to be good carb and try it out - I'm guessing if fuel is the problem its likely to be the carb and you can't argue with a substitution test. Also check that you have no intake or exhaust leaks, which can cause the popping you describe. Clean your air filter. It could also be your cam sensor getting hot and fucking up the timing. Also make sure you have no corrosion in the EHC - pull the plugs (EHC) and dielectric grease it. Did the 06's have the TP rocker boxes?

 

[MARV]

could be the bowl vent screw in the carb.

needs to be taken out with certain type of intakes.

 

[Vegas]

Crank sensors usually work or they don't. Seems strange it would take so long for the carb to act up. They get warm with the engine. I am leaning towards a connection at a terminal at the EHC or ignition module, or ignition module, EHC, Coil. Unplug them and look for a spread terminal. There needs to be some drag on the terminals. If it's been apart that many times by differrent folks a spread terminal is a real possibility. Pull on wires with it running to see if it dies. If you have a wire that is close to an open circuit it will create heat and eventually cause problems. Look at places where it could rub, get hot, hit by road debris. I would also check the petcock for restriction.

 

[k9nut]

Thanks for all the help guys. I will keep you posted on the fix when I find it.

Gary C

 

[N8KAM]

Crank sensors usually work or they don't.

For what it is worth..... Unless a bike is different... i run into cam and crank sensors that fail when hot quite often on autos and trucks... cool down and there ok again till hot again..

The heat relation has me wondering.....

I might try a coil if you have one handy...

Now just kind of thinking out loud here..... if you look at the ignition module with the bike acting up do you think it would be possible to see a fluctuation in the led flash if it was the ignition dropping out?????? Opinions anyone??

 

[RRRUFF]

I am betting "ignition module".

 

[mcgroom]

I would start with the carb. You mentioned it had been adjusted but has it ever been apart since the pipes were added?

With nearly 10% Ethanol in the fuel today, it is fucking up all kinds of stuff. And a lot quicker than what you would think.

Pull the bowl, clean it up, replace the jets and see what happens.

The smallest piece of debris can shift around in a jet and reek havoc.

Just my 2 cents.

 

[beast30]

For what it is worth..... Unless a bike is different... i run into cam and crank sensors that fail when hot quite often on autos and trucks... cool down and there ok again till hot again..

The heat relation has me wondering.....

I might try a coil if you have one handy...

Now just kind of thinking out loud here..... if you look at the ignition module with the bike acting up do you think it would be possible to see a fluctuation in the led flash if it was the ignition dropping out?????? Opinions anyone??

N8KAM....your right the autos and such do it quite a bit with the crank sensors heating up then puking.

My Husky did this same shit last year..... Run great then after mins on the road it would sputter then come back then sputter....on and on for. then it would just die completely.

I let it sit for ohhhh say 7-10 min. Fire right back up just like nothing ever happened. Then start riding again and I could only get a 5 min. down the road before it would act up again.

Ended up changing the sensor......GOOD TO GO. Second 1 I've had to replace in 6000 miles.

 

[Vegas]

I was just thinking it was weird that it would start missing then gradually get worse if it was a crank sensor. Hate those intermittent problems....they are the toughest. Definitely would take it out and get it hot and check the crank sensor. It's been a long time but should have AC voltage but would have to check the manual for specs.

 

[coach]

Some time you have to think out-of-the-box. A buddy of mine was go crazy with a similar problem with an in-board ski boat. Did all the things you have done, twice, including flushing the gas tank. These boats sit for a couple months during the down time in the winter and gas additives along with winterizing is common.......he had done all the right stuff........Bottom line..after replacing ignition module, plugs and wiring, carburetor, gas lines, filters......sure I left out a couple things. The problem turned out that a Bee/yellow-jacket crawled in the over flow for the gas tank. I guess flushing the first time didn't turn up anything.....second found it in the feed line screen in the bottom of the tank. :bang:

Just an experience that came to mind. In his case, he would have preferred investigating the obscure before replace so many expensive components. Good Luck and keep us informed with your progress in solving this.

 

[reloaderbmg]

to check if its heet, use wifes hair dryer on sensors [one at a time] to find the bad on if there!
also pull line of carb and let flow check volume, make shure you have no air bubble in that line, [air will slow gas flow and starve engine.

 

[Th3InfamousI]

Now just kind of thinking out loud here..... if you look at the ignition module with the bike acting up do you think it would be possible to see a fluctuation in the led flash if it was the ignition dropping out?????? Opinions anyone??

If it's an electrical issue you will definatly be able to see the LED flash on the ignition module when it acted up. Would be a worthwhile and easy check if he lets the bike warm up in the garage to see what happens.

Also, he has an 06 (according to his info next to his post) so no cam sensor just a crank sensor.

 

[pknowles]

Did I miss something or is this a two and a half year old problem