Odd Vibrations...

Mr. Minecraft

Mr. Minecraft

Visionary
Hello once again.

My HS 49cc has been running great for about 6 months, but I have been noticing that at 4/5 speed, it starts to vibrate really hard. Its probable hitting the resonant frequency of the frame, but the thing is it has not done this before. I checked and tightened all the bolts, still does it. There is no rubber or space between the mount and frame, and the chain is at proper tension.

Any suggestions?
-Chris
 
I've had good results changing the frequency by adding lead shot to the handlebars or seatpost tube. Might help...
Works really good getting the bars to stop tingling your hands.
 
Mr. Minecraft said:
Hello once again.

My HS 49cc has been running great for about 6 months, but I have been noticing that at 4/5 speed, it starts to vibrate really hard. Its probable hitting the resonant frequency of the frame, but the thing is it has not done this before. I checked and tightened all the bolts, still does it. There is no rubber or space between the mount and frame, and the chain is at proper tension.

Any suggestions?
-Chris
Click to expand...


chain alignment... check to see your chain is strights from your output to your back tire.. and check to see if your engine is cockeyed or crooked that will cause alot of your issues..

also let it idle and see if it vibrates then if thats the case then its got a pluged jet or pluged idle jet.. swap out gas clean carb etc.. if its only when driving its a moving part aka chain.. or something like that

could also be the 4 g bearing bearings wearing out on the 4 g tranny can wobble replace it or weld it solid..

it should not vibrate what so ever.. also check the clutch shoes see if there is decent even wear if not that could be it.. check the clutch bell see if there is uneven wear on it.. if so replace... check belt tension.. etc..
 
The one thing I am unsure about is how tight the belt needs to be. What do you suggest?

The chain is properly alligned, and it only vibrates when going 4/5 throttle. If I slam it full open, it gets nice and smooth. The problem is my cruising speed is right where it vibrates :/
 
tighten the rubber belt so that its tight but not too tight.. 1/8 deflection is fine.. to tight and it could snap to loose and slip its a balancing act.. check wheel bearings make sure when you spin the tire that it isnt the source.. aka both front and back...

other than that there is not much i can suggest.. i have the same motor and tranny and mine dosent not vibrate at all.. if all the other things check out its the motor.. it could be
a bad bearing in the crank of the motor.. process of elimination.. just keep at it till youve exhauseted all options.. what you can do is take off the chain and ride it like a regular bike to see if it is the motor....
 
I have probably 230 miles on this chain. It is the chain that comes with the HS kit though, and I have heard that they can tend to be ****ty. What really gets me is that the vibration happens at a specific RPM... If it were a bad bearing or chain etc, shouldn't it vibrate all the time?
 
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On my 5/8 strait shaft model it was vibrating very bad under heavy load.
I had two problems one I didn't shim the centrifical clutch to the crank shaft so there was too much play.
Second the bronze oillite bearing was overly worn.When putting the assembly together make sure you tork the fastener that holds the bearing and assembly down tight with a hardend bolt.
Mine vibated so bad that it seperated the belt pully from the clutch bell.
 
Oillite bearing? You mean the one way bearing that comes out from the large pully?

I am going to go check my clutch and tranny to make sure its all good. I will let you know if i find anything.
 
The oilite bearing is in the clutch bell .
look at the manual that came with the kit.
I have the strait shaft not the tapered shaft.
 
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