Massive vibration on hard throttle

G

Glaze

Member
#1
#1
Having a hard time figuring out what this massive vibration is coming from. On medium to hard pulls on my baja warrior bike im getting terrible vibration thats felt in the foot pegs. Very uncomfortable! Its based on engine RPM and load, not MPH. New street tires and bearings are good. Ive got a modified Baja Warrior frame , GX160 mildly modified with a recent addition of barely used Honda crank, new crank bearing (old one had pretty good play but no vibration) and also just added a TAV chinese knockoff that I purchased like 6 years ago and just installed.

I suspect its the TAV but cant find anything loose or with signs of wear. Could it be the belt it came with? Belt is wearing a little but getting shredded. Bronze bushing is getting worn pretty good. Have less than 2 hours on it.
 
G

Glaze

Member
#4
#4
Think I found the problem. The crank pully journal keyway is getting banged up from back and forth movement. There isn't much surface area to grip! Do they make a longer 3/4 crank for the gx160?

Good thing she didn't come apart on me!
 
Rapidrob

Rapidrob

#8
#8
That is not that bad. You can take a Ball Peen hammer and reshape the key way,following up with a Swiss needle file. Been there done that decades ago and it is still holding up with no wear.
 
delray

delray

Well-Known Member
#9
#9
maybe little more details on whats in the engine. start with the flywheel. billet or steel cast. only reason I ask is,a lot of guys experience vibration with a aluminum flywheel when running a 30 series unit. if you are still running a steel cast then you can more then likely eliminate the problem coming from there and you say it only happen after you installed the 30 series? assuming you ran a clutch setup before?
 
G

Glaze

Member
#11
#11
delray said:
maybe little more details on whats in the engine. start with the flywheel. billet or steel cast. only reason I ask is,a lot of guys experience vibration with a aluminum flywheel when running a 30 series unit. if you are still running a steel cast then you can more then likely eliminate the problem coming from there and you say it only happen after you installed the 30 series? assuming you ran a clutch setup before?
Click to expand...
Delray,

I do have a PVL alum flywheel. Before i used a clutch and it was vibration free. This is my first experience with TAV. Not too impressed, esp with so little contact area with the driver and crankshaft. The warrior is a big bike and the engine has got some mods such as mild cam, billet rod, new rod bearing, stock piston, and slightly worked head, with mild springs and stock everything else.



Doc1976,

Yes im using the keyed washer with a grade 8 bolt but it does not have that large of a flange.


SAT,

There is some play obviously in the crank keyway and the driver key even before when i first installed. I figured the bolt would hold it all together.


Not sure what to do at this point...get a steel flywheel and new crankshaft or replace?
 
delray

delray

Well-Known Member
#12
#12
maybe just for testing purposes install the steel flywheel. at this point your not looking for power so the steel may not be advance like the aluminum flywheel? and before you ride it take a real good look at the driver and see how true it is spinning.
or just mount the clutch back on the bike and see if it go's away.
 
Li'l Popeye

Li'l Popeye

Well-Known Member
#13
#13
I think you're on the right way, with taking the TAV driver off.
Before you had a clutch and it was vibration free.
I assume you had the PVL flywheel when running the clutch.
You changed to a TAV unit and vibration started. Like Delray said, a heavier flywheel will eliminate some of the vibration. But the cause is still there.
I had the same problem; vibration started as soon as the driver started to engage.
There's another thread about it, but here are some pics of what I think cause the vibrations in the TAV driver. (I don't think the keyway is causing any).

^These are the weights at idle. They're centered pretty good. At this point it will not cause vibration.


^These are the weights at full throttle, again they're pretty good centered. This is what it should be...


^...But, the weights can be off-centered like this. Just imagine what happens with 2 weights being off-center like this.
Like Delray mentioned: take a good look at the driver to see how true it is spinning.
Also make sure the inside of the driver is lubed good with dry moly lube,
 
delray

delray

Well-Known Member
#15
#15
yes, that just might help,but first lets try to determine if you 30 series is the problem and if so? then you can go down that path..... thumb1.PNG
also if you get to that point of fixing your problem I would suggest installing the biggest bolt on rear sprocket they sell for the big baja type bikes.(go power sells it)
two things, it will allow it to pull better out of the hole and get the engine up in the rpm's where your power band will be...:scooter:
right now it takes forever for that heavy bike to move out and without a jackshaft. i'm sure it feels like a tank moving.
 
Skipp

Skipp

#16
#16
Just my opinion and that’s all...shaft too short for a torque converter driver...I had same issue on a hs50...a friend of mine turned me in to this trick....cut a piece of Jackshaft stock...drill it through the size you need...be sure the/a key goes through both the pto and the 1” piece you cut and drilled...now make sure your bolt goes in and tightens to spec...issue solved..
DB8A9524-24B2-401E-8648-27D22E745545.jpeg
 
Li'l Popeye

Li'l Popeye

Well-Known Member
#17
#17
Skipp said:
Just my opinion and that’s all...shaft too short for a torque converter driver...I had same issue on a hs50...a friend of mine turned me in to this trick....cut a piece of Jackshaft stock...drill it through the size you need...be sure the/a key goes through both the pto and the 1” piece you cut and drilled...now make sure your bolt goes in and tightens to spec...issue solved..
View attachment 260600
Click to expand...
A "bolt-on crankshaft extension".
 
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