HarleyTechTalk

So my bike, a 2006 88" EFI Softail Fatboy, now at 29k miles, had vibration issues while on a long trip from Wisconsin.  First a little history.  The bike was running perfectly fine around my area until my local dealership in Madison installed an S&S hydraulic chain tensioner upgrade 10 months ago, when I IMMEDIATELY noticed a bit of vibration that wasn't there before (like, out of the parking lot noticed it).  Not terrible, just made my hands numb after 20 miles or so, it just felt different and I knew with no cam or other changes the bike SHOULD run the same.  However they couldn't find anything, and ended up tuning the vibration out, which smoothed things out until about 65mph and above, which made it tolerable in my area.  However after thinking about it, I doubt they spent 10 hours taking everything apart a 2nd time to actually check their work.  That's a lot of company time.

So onto my story.  From Wisconsin I made it to Kansas when I started noticing vibration, and after hitting Amarillo TX and west to Albuquerque NM the vibration was getting worse to the point I aborted my run.  I was stopping every 30 miles or so to let the bike cool because at the time I thought it was heat related as it was 100 degrees in the area at the time.  After many miles of experimentation I found it wasn't the speed I was being forced to run (typically 85mph posted EVERYWHERE) as it was the rpms.  Usually around 2800-3000 rpms is when the vibration was getting pretty intense, feeling it most in the foot pegs and seat, less in the handlebars.  The vibration when starting the day cold would be fairly minimal up until about 5 to 7 miles (when the engine got up to temperature, which is why I thought it was temperature related).  However, in Wisconsin the elevation is about 1,000 feet....and in Texas and New Mexico it was about 5,000 to 7,000 feet.  Now I want to imagine the EFI injection SHOULD compensate for this.  It definitely wasn't in the wheels, as the vibration immediately vanished upon pulling in the clutch.  Seems everybody's first thought was an unbalanced wheel everywhere I went.

Dealership in Amarillo TX found a loose top mount bolt loose, but that ended up changing nothing and onward west I went into Albuquerque dealership, who gave me a couple possibilities- both rather expensive, their first thought was the internal balancers, or the compensator.  I have since scratched off both these as possibilities as I have no rattling in the primary for a compensator, and I'm told the internal balancers would make the bike vibrate ALL the time, immediately upon starting and all.  Not to mention that it would be unaffected by elevation.

So onto my elevation subject.  Upon abandoning my run west I headed straight north into Colorado, which was a great reprieve of the 85mph speed limits and let me take it easier at the slower mountain road speeds.  Despite the elevation of 10,000 feet the bike was performing well at lower rpms and speeds of under 60mph.  The local dealership, Avalanche, was absolutely fantastic btw as they were the first dealership to really listen to what I was saying, but again came up empty on a solution other that for me to trade in my bike    .  I entered South Dakota and started making my way east on the interstate at 80mph, at the time trying to make miles for the day.  However at 80mph, the vibration was almost tolerable.  Not the having to stop every 30 miles it was in the south.  And as I went further and further east through Minnesota the vibration lessened, effectively back to normal as it was back home.....and that's when I noted the elevation of 1700 feet and dropping.

So when I got into Wisconsin again after over 4,000 miles, I pulled the plugs I had just installed before my trip began and I found the rear spark plug was white, and the front was a tannish brown.  So the rear is running lean.  Now being at high elevation I would think both would be running a bit funky with the thin air, but having one plug vastly different from the other is a big red flag that something is wrong.

I get back home and immediately ride to the dealership that caused the vibration issues in Madison, and the service supervisor is yet again scratching his head.  He's thinking it's the compensator and not the internal balancer (thank god it's not the internal balancer) however with only 30k miles he still has his doubts it's the compensator...and I haven't had any compensator rattling issues.  I am convinced it's something they messed up when putting in the S&S cam tensioner setup, maybe they didn't line up the rear cam correctly?  If I can get them to open it up and check their work without costing me anything that would be nice.  I'm thinking of ways for them to do it, I'm considering ordering them to check the crankshaft runout to force them to open it up again.  I'd like to know what it is anyways, I forgot to have them check that the first time.  Or I may have it dyno tuned somewhere, maybe I'll find answers there?

So full details of my bike, for reference:
88ci engine
6 speed screamin' eagle transmission
Master Tune II tune
S&S intake
V&H ProPipe
203 Screamin Eagle camshafts

I've found the sprocket on the pinion shaft, that is used to time the 2 counter balancers moved on the shaft.
John

You said they originally managed to tune the vibration out when it showed up? Do you have the original tune before they worked on it?  How about you download what it's doing now and compare cylinders.  It may be possible to determine by timing and AFR changes if the rear cam is off.  Ideally you would want the dealer to pull the timing cover and find the problem so you don't get blamed for monkeying with it and finding an abnormal tune characteristic may be what it takes to get them to check.

As John Sachs says the soft pinion bolt can shear when reused also. Either way, IMO it's look inside time.

Quote from: jsachs1 on July 20, 2022, 01:46:14 PMI've found the sprocket on the pinion shaft, that is used to time the 2 counter balancers moved on the shaft.
John

That was a topic of discussion at the Avalanche dealership in Denver.  I didn't fully understand it at the time, but I wrote it off because one, I don't believe it was something affected by the cam tensioner swap job, and it wouldn't be something that comes and goes with elevation.  I'll bring it up to my dealership tho, I don't think they thought of it yet.  I'm thinking it could be a part of the problem tho, as I could be looking at a couple small problems that are adding up to be a larger problem.

Quote from: kd on July 20, 2022, 01:56:12 PMYou said they originally managed to tune the vibration out when it showed up? Do you have the original tune before they worked on it?  How about you download what it's doing now and compare cylinders.  It may be possible to determine by timing and AFR changes if the rear cam is off.  Ideally you would want the dealer to pull the timing cover and find the problem so you don't get blamed for monkeying with it and finding an abnormal tune characteristic may be what it takes to get them to check.

As John Sachs says the soft pinion bolt can shear when reused also. Either way, IMO it's look inside time.

Couldn't agree more kd, I'm not touching anything so I don't get blamed for a problem that I didn't cause.  I don't know what kind of records of tuning the dealership keeps but tuning is definitely on the table.  Too bad they don't have a dyno tune there tho.  I don't know how to download the tune at all at home, I really should learn how. 

Oh btw, I didn't find any head gasket leaks or anything like that in the rear cylinder that would explain the lean condition.

It didn't vibrate before they worked on it.
Now it vibrates immediately after they worked on it.
I'm just throwing spitballs here, but I'm thinking it might be something that happened when they worked on it.

Quote from: Hossamania on July 20, 2022, 02:09:38 PMIt didn't vibrate before they worked on it.
Now it vibrates immediately after they worked on it.
I'm just throwing spitballs here, but I'm thinking it might be something that happened when they worked on it.

EXACTLY MY THOUGHTS!  I think the local service manager is tip-toeing around this to avoiding it.  I kept bringing this up to the dealership service departments in other states but oh no no no....it's the internal balancer...no no no...it's the compensator.  So aggravating when people don't listen to me because I'm just another stupid customer.  That's what made Avalanche HD in Denver really nice, they actually listened to me.

I'm not sure how they "tuned" out the vibration, but my guess is it may be off a tooth.
It should be pulled apart and double-checked.

Quote from: SmokyOwl on July 20, 2022, 02:05:00 PM

Quote from: kd on July 20, 2022, 01:56:12 PMYou said they originally managed to tune the vibration out when it showed up? Do you have the original tune before they worked on it?  How about you download what it's doing now and compare cylinders.  It may be possible to determine by timing and AFR changes if the rear cam is off.  Ideally you would want the dealer to pull the timing cover and find the problem so you don't get blamed for monkeying with it and finding an abnormal tune characteristic may be what it takes to get them to check.

As John Sachs says the soft pinion bolt can shear when reused also. Either way, IMO it's look inside time.

Couldn't agree more kd, I'm not touching anything so I don't get blamed for a problem that I didn't cause.  I don't know what kind of records of tuning the dealership keeps but tuning is definitely on the table.  Too bad they don't have a dyno tune there tho.  I don't know how to download the tune at all at home, I really should learn how. 

Oh btw, I didn't find any head gasket leaks or anything like that in the rear cylinder that would explain the lean condition.

It is possible they tuned one or the other cylinder to balance the firing somewhat.  If the tune is real lean on the rear that's a  it of a red flag.  If it's real lean the fact the tuner left it like that is troubling too.  Going on a trip and experiencing elevation could have been fatal.

If you want to try to download a TTS tune you can go to the Master Tune site and download the suite of apps they have.  One of them will give you instructions on how to do it and save it for viewing.  You can also follow the instructions on interpretation of the saved info. Your dongle might have the original tune in the saved history also for comparison.  Who knows, something may show up as way different between the front and rear cylinders.  Do a compression check and if they are close their tune should be too.  A little different is no biggie and somewhat normal. 

BTW You will need the cables Mastertune names but they are Harley and it may even be possible to borrow a set if you know anyone that may use them.

I like kd's idea of doing a compression test, a very simple test to at least start the diagnosis.

A minor difference found in compression, 154psi in the rear, 160psi in the front.

Quote from: SmokyOwl on July 21, 2022, 11:19:09 AMA minor difference found in compression, 154psi in the rear, 160psi in the front.

Not too much difference to worry about. Leads one to think that the cams are not off. Test was done with strong battery, throttle plate held open?

Quote from: Hossamania on July 21, 2022, 11:25:03 AM

Quote from: SmokyOwl on July 21, 2022, 11:19:09 AMA minor difference found in compression, 154psi in the rear, 160psi in the front.

Not too much difference to worry about. Leads one to think that the cams are not off. Test was done with strong battery, throttle plate held open?

  Battery is fine, I didn't know about the throttle plate being held open tho    what difference does that make?  I'll have to try it again late tonight if it's really important.  I did two readings on each cylinder, both had about 1psi in difference after 8 cycles. 

I think since the spark plug replacement they've had about 500 miles on them; the rear cylinder looked a touch leaner than the front but it's really difficult to judge with such few miles on them....and I am predispositioned to look for that lean condition too now.

Holding the throttle open (be sure the plate is opening) will raise your compression readings as the cylinders can pull as much air as possible. It may show a greater disparity in readings between cylinders, but will give a true reading.

  Absolutely true.

Going by the motor specs provided, the cranking compression should be about 158 psi,  +/- 5 psi.

Assuming the 88 inch is stock compression and head gasket.


88ci engine
6 speed screamin' eagle transmission
Master Tune II tune
S&S intake
V&H ProPipe
203 Screamin Eagle camshafts

So there IS a notable difference between holding the throttle open and not: 

Holding the throttle open:  Rear- 165psi  Front- 162psi, a noticeable difference in the rear cylinder from the previous 154psi reading when not opening the throttle. 

I noticed sometimes I would get about a 5psi increase from these findings in both cylinders on occasion, I'm assuming this is from some kind of unique position of the piston in the cylinder when starting to crank or possibly just a glitch reading in my equipment.  But other than that I was getting very consistent pressure readings.

I do now recall when talking with the service manager about the sprocket and pinion shaft, I'm pretty sure he mentioned that it cannot move out of position because it's locked in place with a keyway.  Maybe he was referring to something else, my mind gets fuzzy in the memories.  I'm unfamiliar with these components and what they do, I tried looking them up but I'm still a little confused.  It doesn't look like a part that would be touched when doing a cam tensioner swap?

Quote from: SmokyOwl on July 22, 2022, 01:02:06 PMSo there IS a notable difference between holding the throttle open and not: 

Holding the throttle open:  Rear- 165psi  Front- 162psi, a noticeable difference in the rear cylinder from the previous 154psi reading when not opening the throttle. 

I noticed sometimes I would get about a 5psi increase from these findings in both cylinders on occasion, I'm assuming this is from some kind of unique position of the piston in the cylinder when starting to crank or possibly just a glitch reading in my equipment.  But other than that I was getting very consistent pressure readings.

I do now recall when talking with the service manager about the sprocket and pinion shaft, I'm pretty sure he mentioned that it cannot move out of position because it's locked in place with a keyway.  Maybe he was referring to something else, my mind gets fuzzy in the memories.  I'm unfamiliar with these components and what they do, I tried looking them up but I'm still a little confused.  It doesn't look like a part that would be touched when doing a cam tensioner swap?

I feel that some on this thread are missing what I posted. There's a gear on the flywheels ,that is in the area of the flywheel bearing race on the right side of the flywheels (pinion shaft extends from it). It is a pressed on gear, with a timing mark on it. That mark is used to coincide with (timing) the 2 counter balancers, which also has the mark on each of them. That gear (on the pinion side of the flywheels, can move out of time, which will let the counter balancers go out of time.
John

If that is the case, it is just a coincidence and bad luck that it happened about the same time as the tensioners were changed? It doesn't sound like it happened due to anything the dealer did. Am I reading that right, John?

Yes I believe that was exactly what the manager and I were discussing, and he said that it was impossible because there was either a flat spot or keyway that made misalignment impossible.  However if by chance it COULD spin that could be the case if they had hit it with something maybe?  I suppose it is a possibility somehow if people are talking about it.

Quote from: SmokyOwl on July 22, 2022, 04:47:57 PMYes I believe that was exactly what the manager and I were discussing, and he said that it was impossible because there was either a flat spot or keyway that made misalignment impossible.  However if by chance it COULD spin that could be the case if they had hit it with something maybe?  I suppose it is a possibility somehow if people are talking about it.

The tell tale of out of time cam(s) is usually a wide compression variance.  That doesn't seem to be the case now that you've done the easy non invasive compression test.  I would say that John has nailed it.  He very knowledgeable and usually knows what he's talking about too.     

Quote from: SmokyOwl on July 22, 2022, 04:47:57 PMYes I believe that was exactly what the manager and I were discussing, and he said that it was impossible because there was either a flat spot or keyway that made misalignment impossible.  However if by chance it COULD spin that could be the case if they had hit it with something maybe?  I suppose it is a possibility somehow if people are talking about it.

IMO, he's wrong. That gear can spin, I had a bike in for work, in April with that problem. Balancers off by 2 1/2 teeth (I replaced the wheels, with a known good set, Ok by customer)( there's a shop in So. Fla. that claims they repair that problem), and I've also found on another job, a loose pinion bearing race. I'm sure you can get more info from Dark Horse Crank Works.
John

I'm sorry, but I'm seeing over and over that the gear on the pinion shaft can't rotate.  I'm seeing many pictures where there's a flat section on the shaft so the gear can only go on one way.  THIS IS NOT MY PICTURE, it's just for reference on somebody else's 88 twin cam that had some scoring issues and antoher where they're putting on an S&S gear set.  You can clearly see the flat area where the sprocket would go on, and it cannot rotate around the shaft?  I'm assuming this is what the dealership service manager was referring to.  So if this sprocket cannot go on in the wrong position, I'm confused as to what can?  Is the entire shaft rotated in the wrong position?  I think I need to get on the same page, I'm a little confused as to what's mispositioned.  Is the bottom gear mispositioned in the wrong slots of the timing chain?

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Do not upload images taken from other websites. Doing this will get you banned. Use an IMG tag instead.  - Coyote

You're missing John's point. That's not the balancer sprocket. You have to dig deeper to get there.

OK gotcha.  So we are talking about splitting the entire case open.  I was really hoping to avoid that    so what I'm seeing from these pictures is an alarmingly thin sprocket that's just pressed in place on the crankshaft.  Only being held in place with compression- I'm pretty shocked by this given it's critical component status.  Once repositioned, can it be welded into place or anything to prevent it from happening again?

So after admittedly a pretty short period of thought here, is it possible for the mechanic to force the crankshaft  to spin a little while the internal balancing chain doesn't move when putting the bolt for the lower sprocket on or off?  Does that makes sense?  Like if they forgot to put the locking block in the timing chain so stuff didn't move, it started to move and then it's "oh crap I forgot the block".  So while the crankshaft rotated for a little bit, that sprocket didn't move and the sprocket got itself misaligned on the crankshaft from the crankshaft turning a little.  I'm not sure of how much force it would take to break that rear balancing sprocket loose off the crankshaft in comparison to the torque of breaking the crankshaft end bolt loose or tightening it.