Greetings HD Forums,

I have a problem that has plagued me for months and cost me some money and a lot of time. I am really hoping you geniuses can help me. I will start by describing the problem, then list everything I have done.

Symptoms:
While riding by myself (I'm a big guy, 300lbs), when I hit a good size dip, I will feel a quick loss of power to the wheel, like the belt slipped a tooth, the engine will rev for a split sec then stutter like it is going to stall, even has stalled a couple of times. With two riders, add another 150lbs, the problem is much worse and can even stutters from take off. And when I say stutter, I mean a jerk, just like a tooth slip and when the next tooth reengages it jerks, but then causes the engine to stutter and possibly stall.

Troubleshooting:
1) Tried to adjust the belt, but found it was already adjusted all the way out, but it is close to what it should be. There is very little room for adjustment on the '04
2) My first advise from the Harley Parts Counter was that the ethanol eats the fuel hoses. I figure she has a good it of miles on her, wouldn't hurt to freshen up the fuel system, so I replaced lines, filter, everything in the tank but the pump. No change, but I kind of figured that.
3) Going back to the belt, I went ahead and replaced the drive belt. After seeing mixed reviews, but mostly good, I went with the Falcon belt. After a few busted knuckles, the new belt is on, adjusted to proper tension and everything is glorious. She is running great, no stutters with two people, perfect! Then after a couple of hour rides, we hit a good size dip, and boom, stutter. After a bit of cussing, I measured the belt tension and sure enough, it is loose. Adjusted the axle out some more and everything seems OK again. (Yes axle nut was tight, adjustment screws didn't move, it is like the belt stretched) Shortly after that, after a couple of short 20 min rides to work with both of us on it, it started again. This time the adjustment screws went all the way out. I'm back in the same boat I was with the old belt. Seemed OK for a couple of more 20 min rides to work, and now it is stuttering again. After measuring the belt tension, it is just barley out of spec this time.

Could this belt just be crap? What belt is recommended for a heavier load? Or is something else going on that I am not thinking about? Any help is greatly appreciated before I go through changing the belt again.

 

Did you use loctite? (I had an Indiot (indy idiot) that was allergic to the stuff, so now I don't assume the basics.)

Did you buy the bike new? This is easier to keep track of all the mods than buying used.

What size front, rear and belt is on the motorcycle now? (If you bought new, this saves you from counting the teeth on the front and rear pulleys.)

When was the last time the clutch plates were replaced?

Primary chain tension good?

 

Thanks for the reply.
Yes on the Loctite, and when the belt is loose again, the adjustment bolts are still in the same place. Right now, I know that for sure because they are adjusted all the way. So it really does appear the belt is stretching. I did find a review of this Falcon belt talking about stretch, so I just ordered an S&S belt that is said to be stronger and even less chance of stretch that an OEM.
I bought the bike from my brother who bought it stock, so I know what mods have been made and it is still running a 70T pulley, so the 1 1/8, 135T belt should be the right one, and it does seem to fit in the beginning.
The clutch plates are still stock, I am sure. I thought briefly about that, but the clutch acts perfectly. If I pull the clutch before hitting a dip, then I can avoid the stutter. Would the clutch plates still be suspect?
Yes, I checked the Primary chain each time I adjusted the secondary belt, just to make sure.
We shall see what this S&S belt does, I just wanted to see what you guys thought so I don't keep pulling the primary off to change the belt. Thanks for the ideas, if the S&S belt does it again, then I will certainly look into the clutch plates. Something's gotta give.

 

OK, got back home and measured a little better. The belt has NOT stretched this time, but it certainly tried to stall with my girl and me on it. Something else we noticed on this last ride was that when going up a hill, it would do it every foot or so, sometimes balk a few times. The way it acted up the hill, I am not so sure it is a belt slip anymore. It was more like it kept trying to stall under the heavy load. Note this is after about 15 minutes of ridding fine.
First thought is plugs, but that was actually the first thing I replaced when this all started, along with the fuel parts. This bike is EFI, so could it be an injector? or something more simple?
While looking everything over good this last time, I noticed a small oil leak looking like the a rocker box gasket, but that wouldn't cause this.... would it?

 

Does it backfire thru the intake? My guess is the fuel line inside the tank has cracked or has pin holes. Common problem with 2000-2007 v-twins EFI. It happened to my 02 Fatboy last year with about 21,000 miles. My indie told me ethanol is the culprit.

 

It has backfired a couple of times. HD Parts guy told me the same thing about the ethanol, so I did replace all the fuel lines and everything inside the tank except the pump itself. I am considering running an injector cleaner through it.

 

I have to wonder if the front 32t pulley has been changed out for a smaller one. That would explain why you are reaching the end of the adjusters right away.

Try this the next time you remove the outer primary:

Remove the compensating nut (40392-91) and add a .030 spacer shim (43290-82) because there was a service bulletin stating that the nut was too long.

 

I have read this thread and am puzzled about the belt running out of adjustment so quickly. Pulley,s are all stock and I was starting to question the swingarm or bearings ? I had a outer primary bearing go bad and with the bike on the lift rear tire in the air ,spin the wheel backwards and you could here it grind, the tech told me usually if the belt was to tight that this would happen. Just a shot in the dark here but I would check the swing arm . Good luck .

 

Thanks guys. I will check.
The front pulley is stock. The only upgrades deeper than pipes is upgraded cams, high flow oil pump, and a Power Commander.
I finally found the diag instructions to check error codes and came up with the P0373 CKP Sensor Intermittent EFI. I don't know if the stall is causing the error, or the CKP Sensor is causing the stall, but for $50 and 10 min, I will try replacing it as well.
Captain Itch, I had suspected the swing arm as well, but I was told the shocks hit the wall before they are too far to cause a problem. With both of us on the bike, there is still some play in the shocks. I am unsure about the outer primary bearing question, might you have a link describing it more?

 

Your shocks maybe worn, or not enough pre-load on them. This will allow the bike to sag too much resulting in the swingarm to effectively move too high and thus shorten the distance between the final drive pulleys, which can cause belt slip. Have someone check and set belt tension with and passenger are sitting on the bike, then check with the bike unloaded to make sure it's not too tight.