Modern Vespa

I just replaced my Idler Pulley it was getting loud and I would smell rubber after riding. ( The Hot neighbor looked out to see me smelling my tire and belt housing at the back. She asked what the hell I was doing ) and I am still hearing a squeaking from the belt housing.

Was thinking of opening it back up and running the motor with the cover off.
So, any problems doing this? I can't think of any as long as I don't put stress on the driven pulley, as there won't be an outside bearing.

I hear the noise at idle, so I won't have to rev the motor.

I wouldn't drive it like that, but I did that once to try and find a noise too.

Important tip. Make sure you replace the oil filler cap. If you don't you will find out exactly how much of a bitch synthetic oil is to clean up, and how many places you will find that it goes.

only on a 250. the 400/500 is on the other side of the engine.

Ah. And IMHO another reason to upgrade. It is a serious bitch to get the cover off over that stupid thing.

If you run the motor without the belt in place you should be OK. On the 250, IF you install the the belt then the spyder assembly must be mounted to secure the driven pulley shaft. The process is not possible on the 4/500 since the outer CVT case is the driven shaft support.

I did this a few days ago on my 400. The reason is the belt has 8,100 miles on it and the last time I rode it I smelled a burning rubber scent at the end of the ride. I inspected the belt by taking it off and bending it backwards to see if there were any cracks in between the inside cogs. There weren't so I re-installed it after looking @ and cleaning the clutch rollers too. I had to cut a 3/4" piece of pvc 5/8" wide for a spacer before running the belt to make sure it was OK between the 2 pulleys on the rear pulley. Otherwise the rear pulley would drift out when the belt was operating. I also had to make sure the front pulley nut was tight or it would fall off during operation. Still don't know where the burning rubber smell came from but I'm not done yet.

Cooking something on the muffler?

My MP3 has what I would call a burning rubber smell too but no cause has ever turned up. I think it's just the normal odor of the exhaust gases.

You can't - well highly inadvisable.
The bearing that supports the rear driven pulley/clutch shaft is in the cover. Without it the clutch can move in and out and it will place a torque load on that shaft - which goes into the rear hub.

The rear shaft won't be turning unless I give it gas to engage the clutch will it? Just the rear pulley will be turning.

Nope - it's a centrifugal clutch - the pulley & belt will be turning - just the clutch won't be engaged. There will be force on the shaft from the driven pulley - ie - it's under tension

for a testdrive its oke but you need a pipe between the nut and the clutch bell where the bearing used to be otherwise your clutch bell will fly off with all kind of damage

Maksor I respect your abilities a lot - but have you ever done this yourself? Without support at the end the torque will pull that shaft towards the front and those bearings and gears are not designed to withstand off-axial loads.

yes done it a few times but with a pipe between the nut and the bell

and just for a few miles not more testing

Don't need to ride it, just want to see if the belt is rubbing.

I was thinking last night, I don't have as much low end power as a use to, (Have Dr Pulley Sliders and a fuzzy washer) Wonder if one of the sliders flipped over. Could that cause the belt to rub?
Took it apart one time and one of the sliders have flipped over.
Guess I'll check that while I have it apart again.

the bearing is there to close / pull the axle outwards so you wont demage the gearing behind it

what ever you do don't test it without the clutch bell if you run the engine without the bell you need to buy a new clutch

This has to be on the center stand with the brake off. No resistance in the wheel and thus not much pull. Roll the throttle on easy to not jerk it. Should be OK but be careful. Pipe for nut to tighten against is also critical as Maxsor said.

If you are not 100% sure you understand the instructions don't do it.

Don't think I'll even have to give it throttle. It's squeaking at idle.
Just went out to go to another building and the noise doesn't seem as loud.

Correct. I put the pvc piece(pipe) on and operated the belt on my stand(no load), not actually riding it that way. The pvc takes the place of the cover temporarily. Now I have the cover on it and will ride it that way.

I like what sidecutter says.

Figured out why my belt was rubbing.

The variator half the roller/sliders go in was worn out. A bunch of the metal where the sliders slide on the sides was cranked away and not letting the sliders slide smoothly and they were getting caught up and binding.
Replaced the whole variator with the one from my parts bike and replaced the Dr Pulley sliders with new ones.
Man, what a difference that made.
My weird idle dropping issue while coming to a stop is gone too.

nice info. thanks for sharing

My 400 belt, rollers are fine now and I'm just going to see how many miles I can get out of the belt before it needs replacement. Right now it's @ 8,403 miles. No burnt rubber smell.