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[Abbynormal]

Would appreciate any ideas as to why my bike started an unusual and fairly severe vibration. We have replaced all 3 motor mounts, both stabilizers, removed primary cover and disassembled and inspected alternator, clutch assembly, inspected frame for cracks, checked the main x-mission shaft for out of round, found only 1.5 thousands run out . The vibration is confirmed to be the engine. It is not involved with the frame or wheels. It is severe at around 11-1300 rpm and begins to be much improved at the higher rpm or when the bike is accelerating. It can still be felt in the pedals as a high freq viberation that tends to put your feet to sleep. This was a very, very smooth riding bike and this change happened overnight. The only thing remaining that we suspect is the flywheel somehow is now out of balance. Any new or additional thoughts will be appreciated.

[MUFFMAN]

Check to see if the rear of motor is touching the frame. Just 3 weeks ago my friends 01 Road king did the exact samt thing & it was due to rear mount coming loose. I guess when it was tightened down everything shifted just enough. Idled fine but around 1300 RPMs almost unbearable. Hope this helps. THE MUFFMAN

[Abbynormal]

Muffman, thanks for your thought about the bike. We have now narrowed the problem down to the possibility of a broken piston ring or shifted crankshaft. The bike is at the shop and being inspected. Hope to hear from the shop by mid week. Will do a top end if it is the ring and install a new engine if the crank.

[Abbynormal]

Received an update from the shop yesterday. Apparently valve guide seal on rear cylinder "weeped" or leaked oil for a long time. Build up of carbon on the piston and valves was excessive and was causing valve leakage resulting in low compression and the out of balance condition. We are doing a complete top end overhaul. Bike only had 21,000 miles. Should not have to do this work so soon. This out of balance condition has been very difficult to diagnose and did not reveal itself until we finally saw a puff of white smoke from the exhaust when cranking the engine.

[RedFXR2]

Apparently valve guide seal on rear cylinder "weeped" or leaked oil for a long time. Build up of carbon on the piston and valves was excessive and was causing valve leakage resulting in low compression and the out of balance condition. We are doing a complete top end overhaul.

This gives my flashbacks to my British sports car days.  Those things needed to be "de-carbonized" periodically for exactly the situation you had.  Back then, it was regarded as normal maintenance--nothing wrong.  Pulling the head and scraping the carbon off the piston tops.  What a way to spend a Saturday.

One of the many reasons I gave up my hobby of British sports cars.

[Abbynormal]

Bike back from the shop with top end overhaul. In the process of breaking in now. Still some excessive vibes but better. Today we loosened the top stabilizer link and front motor mount then cranked the engine for 30 seconds. That allowed the engine to seek its own center. Tightened all back down and did find some improvement. This bike is now smooth enough to ride but is not as smooth as before. It is possible that it will improve when the engine mounts soften a bit with miles and time. This has been an expasperating and expensive problem.

[elvislee]

Hey Abby...Well you finally got it back...That's great! Hope it settles in as you say and your back to riding the way you like...I know you'll be glad too. Enjoy and let us know how that yellow 4 is doing...Best to ya

[Abbynormal]

Our mechanic has now found the problem. He says that the bike is haunted (has demons). Bless his heart, he is a v-twin specalist and a grad of the Harley school. He has pulled out his remaining hair attempting to find out why this bike vibrates. He has now even gotten the Harley School instructors involved. After hearing all of the various attempted fixes we have done to the bike all persons have agreed on the same answer, (we don't know). Jim said that in all of the thousands of engine rebuilds that he has done, he has never felt a bike shake so much. After putting the bike back on the lift and installing new rocker boxes (others warped) the bike quit shaking so violently, NO, that had nothing to do with the shake but it abated. Jim has reported that he fixed it. The Harley instructors quickly asked how. He said, "I don't know". Anyway, bike is home and we are determined to ride it 1000 miles to see what falls off (hopefully it won't be the rider) or gets better. Still think the flywheel is the culprit and is somehow moving. Stay tuned for the exciting finale.

[Abbynormal]

Woooow,  beeebbebnnn ridddin mmmyyy bbikke, it sstttillll ssshhhakes.

[RedFXR2]

Our mechanic ....  says that the bike is haunted (has demons). Bless his heart, he is a v-twin specalist and a grad of the Harley school.

Hey, I give himpoints for his tongue-in-cheek honesty.  I mean, he could have said something about the franistan binding with the muffler bearing.

After putting the bike back on the lift and installing new rocker boxes (others warped) the bike quit shaking so violently, NO, that had nothing to do with the shake but it abated. Jim has reported that he fixed it.

So did it actually improve temporarily, as a result(?) of replacing the rocker boxes?  Since he had to remove the front engine mount in order to lower the engine as a part of this repair, then re-install the front mount when done, could something have changed about the front mount during the process?  and it's now returned to it's previous state?   Could it be over-tightened, or a washer put in the wrong place, maybe?  Or maybe too loose?  I've done this job and I'll try to think about it, look at my bike, and see if I can remember any particulars.

Woooow,  beeebbebnnn ridddin mmmyyy bbikke, it sstttillll ssshhhakes.

Sounds like a blast!  OK, seriously, is it a high frequency buzz or a more defined "coarse" vibration?  Do you feel it in the pegs or bars or both?  At idle and at cruise?

[edit: never mind, I just re-read your first post.]

[RedFXR2]

It is possible that it will improve when the engine mounts soften a bit with miles and time. This has been an expasperating and expensive problem.

Just a thought but it's been my experience that rubber motor mounts don't soften with time, they harden.  If they soften it's usually due to prolonged exposure to oil or something that has damaged the rubber.

[RedFXR2]

We have replaced all 3 motor mounts, both stabilizers, removed primary cover and disassembled and inspected alternator, clutch assembly, inspected frame for cracks, checked the main x-mission shaft for out of round, found only 1.5 thousands run out . The vibration is confirmed to be the engine. ...This was a very, very smooth riding bike and this change happened overnight.

Well, never mind my motor mount thoughts.  Since the bike went from good to bad overnight, it would appear that something has at least partially failed, as opposed to gradually wearing out.  Evo bottom ends are quite tough--properly cared for they'll go 100K.  But "stuff" can always happen.

Today we loosened the top stabilizer link and front motor mount then cranked the engine for 30 seconds. That allowed the engine to seek its own center. Tightened all back down and did find some improvement. This bike is now smooth enough to ride but is not as smooth as before.

Could you somehow quantify the degree of improvement here?  The self-centering thing will work somewhat, but apparently you've got bigger problems.  Still, I'm curious as to how it helped at all if the motor has an internal problem.

[RedFXR2]

Received an update from the shop yesterday. Apparently valve guide seal on rear cylinder "weeped" or leaked oil for a long time. Build up of carbon on the piston and valves was excessive and was causing valve leakage resulting in low compression and the out of balance condition. We are doing a complete top end overhaul. Bike only had 21,000 miles. Should not have to do this work so soon. This out of balance condition has been very difficult to diagnose and did not reveal itself until we finally saw a puff of white smoke from the exhaust when cranking the engine.

Hmmmm.  How about this alternative scenario.  Could the rear connecting rod be ever so slightly bent?  Hence the low compression?  Maybe at some point the piston touched the valve, ruining the guide seal. 

It is severe at around 11-1300 rpm and begins to be much improved at the higher rpm or when the bike is accelerating.

At 21000 miles, you're probably due for a new set of lifters, anyway.  20k is the rule of thumb that I've always heard for Evo lifters.  Could one of your lifters be going soft above 1100 and finally pumping up above that, but never quite all the way?  If so, one valve is never opening fully.  Might cause incomplete evacuation of the cylinder,  hence the carbon build-up.  Would cause a vibration on a two-cylinder motor, for sure.

Just thinking at the keyboard. I'd change the lifters, myself.

[110tHunDer]

 
Could it also be a timing or ignition-related problem?

[Abbynormal]

Many thanks for all of your ideas and encouragement. We really don't believe a lifter is involved because we don't hear anything out of the norm. The timing has been set with a light at 2500 RPM. The bike starts and runs fine. At around 1300 RPM a  "shudder" vibration is felt but increasing the RPM will move through the vibration. Things smooth out somewhat except for the high freq felt in the pedals. It is similar to what you feel in your feet when riding a pre 2004 Sportster. I can ride the bike and will do so for the 1000 miles requested by the mechanic and see what happens. If it gets worse then we either split the cases and search for a bottom end problem or just replace the engine. This FXR has been custom fitted for me and is a pleasure to ride so I am keeping the bike. We will eventually find the cause or replace the engine. Again, I appreciate all of your suggestions.