Low RPM engine vibration

[Goodrich]

I know single piston motors have the reputation of heavy vibration at low RPM but I'm noticing lately that it's getting stronger.  This happens when the motor is cold, as the motor heats up it somewhat goes away.  This has always been the case but in the last couple thousand miles has gotten worse.  I have about 14K miles on it, I get normal oil changes (synthetic) and the valves were checked at about 8500 miles. Once motor comes to normal operating temps it's fine.  The motor seems fine all the way through the RPM range but has heavy vibration in the lower RPM's when cold.  Is this normal ?

[de dee]

what rpm does it do that , Idling or riding, I have 60,000 km. on my scoot and is very smooth except when I put on the rear brake, when stoped,. 

[windwheeler]

I know single piston motors have the reputation of heavy vibration at low RPM but I'm noticing lately that it's getting stronger.  This happens when the motor is cold, as the motor heats up it somewhat goes away.  This has always been the case but in the last couple thousand miles has gotten worse.  I have about 14K miles on it, I get normal oil changes (synthetic) and the valves were checked at about 8500 miles. Once motor comes to normal operating temps it's fine.  The motor seems fine all the way through the RPM range but has heavy vibration in the lower RPM's when cold.  Is this normal ?

Goodrich, I do not think it has anything to do with your motor, unless you would hear really "bad noises".  Its more likely the variator pulleys, weights, or a bad going belt.  I had a similar situation on a GrandVista and the belt blew out soon after that vibration thing started, having only a few thousand miles on it. Actually, the problem were in this case bad worn variator pulleys that allowed the belt to slip, which then chewed itself up...  

Another thing that happened and was much simpler was the center stand rubber bumper was worn out and created "unusual vibrations" through the frame.

[sklnzl]

Normally my scooter does this from a stop ,when accelerate to a certain speed then it disappears , i think it is the stock variator ,this doesn't happen with after market performance parts,according to users that have upgraded.

[BettinANDlosing]

If it happens taking off from a stop, its glazed clutch pads! When they get glazed they "chatter" when taking off instead of a smooth acceleration. I'm not sure if most shops do this, but every bike I service I hit the clutch pads with some 200 grit wet/dry and get them de-glazzed. If you can take your CVT apart, its easy. If not, have your dealer hit the pads next time you bring it in for service.

[windwheeler]

If it happens taking off from a stop, its glazed clutch pads! When they get glazed they "chatter" when taking off instead of a smooth acceleration. I'm not sure if most shops do this, but every bike I service I hit the clutch pads with some 200 grit wet/dry and get them de-glazzed. If you can take your CVT apart, its easy. If not, have your dealer hit the pads next time you bring it in for service.

I agree with BettinANDlosing; if it if's doing it only during take off it is in the clutch, not the variator.

I had a situation where it formed fine rust after longer time sitting, and once the scooter was used frequently again, it went away as it shaved the rust off by itself.   
A friend of mine had the same issue after sitting and rain (rusty clutch housing) and he held the brake for a short time (5-10 seconds) and accelerated/revved the engine in stand-still, and the problem was solved instantly. 

[Goodrich]

I ride the DT quite a bit so it doesn't sit very often or for very long.  I will be getting a new belt soon so I'll have them check everything out and let everyone know what it was.

[mrbios]

I ride the DT quite a bit so it doesn't sit very often or for very long.  I will be getting a new belt soon so I'll have them check everything out and let everyone know what it was.

My guess is the drive train - belt, maybe weights?  I changed my belt early at 10K miles and switched to flat slide weights - to trim RPM's.  My 2005 GV250 running smooth - with normal idle vibration and now 16K miles.

Good job of getting out and really using your scoot.