Engine vibration

HellOnWheels

HellOnWheels

Member
Recently changed stator on my 1999 Vintage Sport. Currently getting a high-RPM engine vibration. Engine is smooth through all gears until the upper end of the RPM range. In 5th gear, it occurs around 85mph and can be felt in the footboards.

What's the most likely cause of this?
 
FrankBDPS

FrankBDPS

Well-Known Member
If it did not do it before the work was done it may be that something was left loose or not properly installed. Also check you're rubber mounts on the front of the engine and back of the transmission. Don't forget to look at the top mounts also. Let us know what you find. Good luck.
 
HellOnWheels

HellOnWheels

Member
FrankBDPS said:
If it did not do it before the work was done it may be that something was left loose or not properly installed. Also check you're rubber mounts on the front of the engine and back of the transmission. Don't forget to look at the top mounts also. Let us know what you find. Good luck.
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A friend who is a reputable professional bike mechanic walked me through the disassembly and reassembly, so I'm pretty sure it's not an issue of something not being done "correctly". When I had the bike on the rack, I noticed that the front motor mount was all kinds of loose (like "the nut was all the way to the end of the bolt" loose) and I cranked it down. It got a lot smoother after that, but at low speeds.

I was headed to a CoC meeting about 50mi away, almost all of it was non-stop high-speed highway travel and started noticing that right around 85mph, it felt like the bike was going to rattle apart. Throttling down to 84mph, it vanished.
 
pauldeepsea

pauldeepsea

Guru
HellOnWheels said:
A friend who is a reputable professional bike mechanic walked me through the disassembly and reassembly, so I'm pretty sure it's not an issue of something not being done "correctly". When I had the bike on the rack, I noticed that the front motor mount was all kinds of loose (like "the nut was all the way to the end of the bolt" loose) and I cranked it down. It got a lot smoother after that, but at low speeds.

I was headed to a CoC meeting about 50mi away, almost all of it was non-stop high-speed highway travel and started noticing that right around 85mph, it felt like the bike was going to rattle apart. Throttling down to 84mph, it vanished.
Click to expand...
Did you check all of your motor mount bolts?
Could be an alignment issue with the motor, primary, transmission?
 
HellOnWheels

HellOnWheels

Member
HMAN said:
Peel the sticky stock wheel weights off and pour some Dyna-Beads in the tires. Smooth as glass, even @ higher end hiway speeds.
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It's not a tire vibration issue, it's a motor vibration issue. I don't have a tach so I'm not sure exactly what RPM it's doing it, but it's at a certain point in every gear. The 85mph just happens to be where it does it in 5th gear.
 
TapioK

TapioK

Well-Known Member
You mentioned the front motor mount was kind of loose, check the rubber on it, maybe it is cracked. Just replaced the front mount on a Harley, it vibrated like crazy. Cheap owner bought a new cheap part with hard rubber, engine still vibrated ... Got OEM part, smooth....
 
cdogg556

cdogg556

Guru
On my 05 Bulldog I had something that seems real similar to what you are experiencing with your bike, somewhere in the 2500 to 2800 rpm range I would get a weird vibration that I could never figure out, took it to the local Big Dog Dealer at the time when they were still in business and they couldn't figure it out either, it wasn't so bad that I needed to deal with it right away, but it was irritating for sure, anyway I think about it now and was thinking maybe the clutch hub nut was coming loose or sumth'n like that and was causing the vibration, hope you figure it out, keep us posted.
 
Marky-Marc

Marky-Marc

Well-Known Member
Just my .02....sounds like an engine to frame alignment.....just what @TapioK said...check the other bolts and replace the RUBBERS...you tightening that one bolt or the others out of sequence....(shit happens) may have moved the engine to frame alignment.....
 
JMont

JMont

Member
I have motor bolted straight to frame on my 03 Mastiff. It vibrates like crazy at mid rpms. Just curious has anyone ever added rubber mounts or know if it should have rubber mounts??
 
TapioK

TapioK

Well-Known Member
JMont said:
I have motor bolted straight to frame on my 03 Mastiff. It vibrates like crazy at mid rpms. Just curious has anyone ever added rubber mounts or know if it should have rubber mounts??
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Is yout engine top mount bolts tight? Common reason for vibrarion.. check all engine bolts while you are there...


Sent from my iPhone using Tapatalk Pro
 
FrankBDPS

FrankBDPS

Well-Known Member
JMont said:
I have motor bolted straight to frame on my 03 Mastiff. It vibrates like crazy at mid rpms. Just curious has anyone ever added rubber mounts or know if it should have rubber mounts??
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I think all the Mastif model bikes should be rubber mounted. It was actually a selling point back in the day. They were basically FXR style bikes with isolated motor and transmission mounts.
 
JMont

JMont

Member
TapioK said:
Is yout engine top mount bolts tight? Common reason for vibrarion.. check all engine bolts while you are there...


Sent from my iPhone using Tapatalk Pro
Click to expand...
Yea they all seem pretty tight. I think it's probably typical for my yr model, i just have never rode another one like it to compare to
 
TapioK

TapioK

Well-Known Member
"Seem pretty tight" is not good enough. -03 has 107 engine, that doesn't vibrate too much. Less than 117.


Sent from my iPhone using Tapatalk Pro
 
JMont

JMont

Member
Hmm well I couldn't get a turn on them so they snug as i can comfortably tighten them. What else could possibly cause vibrations. And i can pull clutch in and it goes away so i kno its engine
 
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