Vibration at high altitude & high rpms

[Ohio HD]

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Twin Cam B-Motor Balancer Mods

[Hossamania]

A friend of mine had to have this done when his balancers shifted.

[SmokyOwl]

A friend of mine had to have this done when his balancers shifted.

I'm honestly worried about the cost.  If the engine has to be cracked open, I might as well have a timken bearing installed.  I'm going to guess something like $5,000?

Is there any way tho that a mechanic caused this misalignment?  It IS a big coincidence that this happened when they were working on the hydraulic tensioner swap.

[Ohio HD]

Is there any way tho that a mechanic caused this misalignment?  It IS a big coincidence that this happened when they were working on the hydraulic tensioner swap.

As you see, the cases have to be split to reach the balancer assembly. You don't split the cases to put in cam chain tensioners.

[Hossamania]

Sadly it seems an unfortunate coincidence until a deeper investigation gets done.

[jsachs1]

If that's the problem, fix it properly, or replace the wheels.
John

[Robb1178]

This happened to mine which was caused by over revving, the higher the rpm the worse the vibration was.  It still ran good just vibrated so bad it made my hands go numb. I ended up rebuilding the whole engine

[SmokyOwl]

This happened to mine which was caused by over revving, the higher the rpm the worse the vibration was.  It still ran good just vibrated so bad it made my hands go numb. I ended up rebuilding the whole engine

I was wondering as to the possible cause so it didn't happen again, thanks for the insight.  I'm probably going to have the sprocket tig welded in place so it doesn't happen again.

I know this is going to make quite a few people on here groan  , but I've decided to keep it an 88 and not going for a 95 conversion.  My reasoning is simply because I don't want to hurt my mileage any more, as I'm currently struggling to get 40mpg, making 200 miles to a tank is really stretching it right now and I don't want it to drop anymore than it already has with the current modifications. 

I actually found a, not sure how to describe it, like a duo company that merged... one makes connecting rods and the other makes pistons.  And they make new setups for 88 engines in multiple bore-wear sizes.  At first I was planning on just upgrading the connecting rods and keeping the same pistons as the compression is quite good right now- thinking why mess with a good thing right?  But then it hit me, the moment the pistons are removed- the rings wear grooves are NEVER going to match up again.  Which means I have to hone the cylinders and get new piston rings at minimum.  Then I thought even with new oem pistons, if the cylinder's are honed then I'll have piston slap and was for a time considering doing the 95 swap until I realized the gas mileage loss.  So I think this company with the new piston sizes for honed cylinders fits the bill perfectly for what needs to be done.  I'm...a bit of a perfectionist 

I'm also strongly considering having the compensator drive front sprocket increased by 1 tooth, lowering the full rpm spectrum a little bit for higher top speed and mpgs.  I thought about lowering the rear chain sprocket at the transmission until I realized when I would be going the typical 30mph around town if I'm in my usual 3rd gear I would likely be lugging the engine at that point and I rather not be in 2nd gear. 

[cheech]

I actually found a, not sure how to describe it, like a duo company that merged... one makes connecting rods and the other makes pistons.  And they make new setups for 88 engines in multiple bore-wear sizes.

Well don't hold out on us, share whoever.
There is some good experience on this forum, they'll let you know if it's up to snuff.

At first I was planning on just upgrading the connecting rods and keeping the same pistons as the compression is quite good right now- thinking why mess with a good thing right?  But then it hit me, the moment the pistons are removed- the rings wear grooves are NEVER going to match up again.   

Breaking news: Rings spin in the bore and on the piston.
Do a search on this forum even. Plenty of talk of it.

[02roadcling]

Don't change your gear ratio higher and expect better mileage because you'll be getting on it all of the time just to maintain speed. When I changed from the stock ratio of 3.15 to 3.37 I gained 4 mpg because I didn't have to keep giving it the gas.

   cling

[kd]

   I get better mileage and power with a 3.15 ratio than the stock 2011 RGU. I run at * 3,000 rpm on the highway and really notice the difference.

[HogMike]

Don't change your gear ratio higher and expect better mileage because you'll be getting on it all of the time just to maintain speed. When I changed from the stock ratio of 3.15 to 3.37 I gained 4 mpg because I didn't have to keep giving it the gas.

   cling

I noticed the same drop in mileage going to the higher ratio on my 2000 88 motor.
I solved THAT issue by going to 95", Andrews cam, re-jetted carb.
Now I get better mileage! LOL
JME
 

[kd]

Don't change your gear ratio higher and expect better mileage because you'll be getting on it all of the time just to maintain speed. When I changed from the stock ratio of 3.15 to 3.37 I gained 4 mpg because I didn't have to keep giving it the gas.

   cling

I noticed the same drop in mileage going to the higher ratio on my 2000 88 motor.
I solved THAT issue by going to 95", Andrews cam, re-jetted carb.
Now I get better mileage! LOL
JME
 

   I went to 120" and got the same results. 

[Ohio HD]

I noticed the same drop in mileage going to the higher ratio on my 2000 88 motor.
I solved THAT issue by going to 95", Andrews cam, re-jetted carb.
Now I get better mileage! LOL
JME
 

   I went to 120" and got the same results. 

I went from 96", to 107", to 117", to 124", and each step used more fuel. I don't cruise much though.   

[jsachs1]

I noticed the same drop in mileage going to the higher ratio on my 2000 88 motor.
I solved THAT issue by going to 95", Andrews cam, re-jetted carb.
Now I get better mileage! LOL
JME
 

   I went to 120" and got the same results. 

I went from 96", to 107", to 117", to 124", and each step used more fuel. I don't cruise much though.   

Us flat landers find the fuel usage increases with cubic inches.
Rings won't spin in 2 stroke engines (transfer ports), and if your CROSSHATCH is screwed up or worn out, they won't spin either.
John

[SmokyOwl]

Well I guess it's good to know that I have the option to keep my stock 88 pistons without worry.  Depending on the bore wear I may go aftermarket if honing is necessary, but I kinda doubt if honing will be necessary with just passing 30k miles this week.

I had some fun messing around with primary and final ratios on gearingcommander.  For fun I found if I tweak each pulley  by fairly easy online options (changing from a 36/25 to a 35/26, and belt pullies from 32/70 to 34/65), I could cruise at 60mph in fifth gear at a little over 2k rpm and leave 6th gear for interstate use.  I'd have a heck of a top speed lol, but then reality hit- it'd probably be a real chore walking away from a stop sign and any traffic jam would be a clutch nightmare.

Unfortunately I was looking at the 30mph speed area and it looks like it would just not work out doing anything less than the extreme option, because if I do the gearing options at anything less I'd be stuck in 2nd at annoyingly high rpms while tooling around town at 30mph.  Oh well, another dead idea.

[smoserx1]

I could cruise at 60mph in fifth gear at a little over 2k rpm and leave 6th gear for interstate use.  I'd have a heck of a top speed lol, but then reality hit- it'd probably be a real chore walking away from a stop sign and any traffic jam would be a clutch nightmare.

Everything about these statements makes me cringe.  Imagine taking a pry bar and moving the pivot point toward you till the bar bends.  That is sort of what you will do to your engine.  Lugging it may tear up the bottom end in time, and in most cases will not increase your top speed because you will not have the power to overcome the wind resistance. You would be much better off cruising at 3000 RPM or above.

[Hossamania]

I could cruise at 60mph in fifth gear at a little over 2k rpm and leave 6th gear for interstate use.  I'd have a heck of a top speed lol, but then reality hit- it'd probably be a real chore walking away from a stop sign and any traffic jam would be a clutch nightmare.

Everything about these statements makes me cringe.  Imagine taking a pry bar and moving the pivot point toward you till the bar bends.  That is sort of what you will do to your engine.  Lugging it may tear up the bottom end in time, and in most cases will not increase your top speed because you will not have the power to overcome the wind resistance. You would be much better off cruising at 3000 RPM or above.

Agreed. That 88" motor will struggle at 2000 rpm to keep your speed at 55mph, and you will find yourself twisting the throttle much more than if you were running closer to 2600-2900 rpm.
I run a 95" with a 5 speed, 3:37 gearing. I get better gas mileage and much better manners running 4th gear in most situations at 55 mph. I can go to 5th and run, but if I'm struggling to hold speed (windshield bucking wind, or some uphill grade, or two-up) I twist the throttle more, the motor struggles a bit, or rather isn't happy, and my gas mileage goes down noticeably.

[SmokyOwl]

I get this a lot when I mention my low rpms at cruising speeds.  I'm not intending to pass anything or even accelerate, and I have enough power to overcome any hill I encounter.  Realistically I was even checking out my rpms last night, and it's actually more around 2,100 to 2,200 in 6th at 60, and I concluded the slight increase in rpms vs what the data online says is due to my rear tire wear.  Honestly I don't have any trouble at all until about 55mph, and that's more like 1,900 to 2,000 rpm- the bike doesn't like that and when that happens it's usually the result of fatigue or lack of attention.  When I'm hitting 3,000 rpm doing 80 down the interstate, I get a significant drop in mpgs, like 4 or 5 mpg less from the increased rpms.  I notice similar results when driving my car at higher speeds/higher rpms too.

[kd]

The reason for the poor mileage has to do with pushing air at 80 mph.  Run those rpm at 60 / 65 and you will be pleasantly surprised.  The engine isn't suckholing to push that billboard through the air anymore.

[wolf_59]

I have a 2004 Fatboy that has had buzzy vibration since it was new, anything over 2750 rpm it would buzz and vibrate horribly higher rpm the worse it was
I ended up with a 95" HTCC cylinders pistons and heads with 57mm throttle body S&S 510 cams upgraded to a 2006 ecm wired in O2 sensors tuned with TTS using 86 octane fuel 180 ccp both cylinders at 6000'elevation and delivers 52-54 mpg consistently a good tune really helped with the buzz vibration above 3000 rpm not as severe as it was stock but it's still there anything above 75 mph checking the mirrors is just a suggestion
I have around 65K miles on it now someday I may have to address the buzz but until then I'll just ride it

[pauly]

Hi SmokyOwl,

Hang on a tic - you say " It definitely wasn't in the wheels, as the vibration immediately vanished upon pulling in the clutch."

If the vibrations cease when you pull in the clutch, it's not the balancers is it? I'd be starting at the clutch unless the vibration persists with the clutch disengaged.

Thanks
Pauly

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

[SmokyOwl]

When I pull in the clutch the rpms drop and are no longer near 3k rpm, I've tried pulling in the clutch then throttling the engine back up to 3k, it's still vibrates be because there's no load on the transmission not nearly as much.  I've beaten that dead horse enough, it's not in the wheels.

[SmokyOwl]

So replacing the compensator didn't do anything, rode pretty much the same as it did before.  The old compensator gear had very little wear with no running issues that I could tell.  It had a LONG way to go yet before there was any issues.  I'd say two of the three had minor wear to it on half of the groove, the other had negligible wear as you could still see much of the original casting.  So....definitely not the compensator as the mechanic suggested.  In the plus column tho it did give me an excuse to install a chrome inner primary cover, so it wasn't all for nothing and it has eliminated the compensator as a culprit.

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[tc1550]

cam off a tooth or torn oil pump oring slight sumping at times ?