First you'll want to remove the plastic spoiler. On GT200 it is secured by two phillips screws, LX's have one screw, GTS250's have one screw and a 10mm nut and finally 300's have the same 10mm nut but a TORX screw at the front.
Now remove the ten machine screws holding the trans cover on, you'll need an 8mm socket on a short extension. On the GT200, the machine screw on the extreme left also has a GROUND wire going to it. It is of VITAL importance that you do not forget to return this ground wire.
Temporarily remove the dipstick and grab the trans cover HERE-
Now, while applying LIGHT PULLING PRESSURE, wiggle the cover towards you, if it's stuck and doesn't want to come off, there are a couple of locating dowels on the back that can sometimes be a bit sticky. Use a small screwdriver if you have to and GENTLY pry it towards you. Alternate between wiggling and prying. Once the cover is loose, lift it up and away from the motor and then replace the dipstick.
This is what you'll see once the trans. cover is removed. The variator assembly is on the left behind the dipstick, an idler pulley is in the middle (not on LX models) and the "clutch pack" and drum are on the right. The toothed drivebelt can also be seen.
You'll want to remove the clutch drum next. It should be able to wiggle off. Sometimes it can be stuck on the splined axle shaft as this one was. Use a VERY SMALL amount of penetrating oil. I HIGHLY recommend DEEP CREEP by Sea Foam. It's an amazing product. Once you've let it sit for a few minutes, hold the drum at the 9 and 3 o'clock positions and try wiggling it off. If it still won't budge, hold the drum at the 3 o'clock position, gently pull it towards you and lightly tap on the axle shaft with a rubber mallet, after a few gentle taps, rotate the drum 45 degrees and give it a few more taps, repeat, repeat and try to wiggle it off again. Eventually... the drum will come off.
Here you can get a better look at what I call the "clutch pack" once the clutch drum is removed.
Now you're ready to remove the variator components. As mentioned earlier, the GT200 variator set up is fairly unique. It's a good idea to dab a little paint on the ring gear and fixed pulley half so you can align it properly during reassembly btw.
Remove the variator nut with an 18mm socket.
Variator nut, starter ring gear, fixed pulley half, washer, belt and "clutch pack"
THIS IS THE WRONG WAY FOR YOUR ROLLERS TO BE INSTALLED-
Examine the roller surface, you are looking for flat spots, these ones look perfect and can be reinstalled, remember the rollers have to be installed with the plastic shoulder to the RIGHT.
This is how rollers SHOULD be installed, plastic shoulder facing to the RIGHT. TO AVOID CONFUSION, BE SURE TO INSTALL YOUR ROLLERS EXACTLY AS SHOWN IN THIS PICTURE THIS IS THE CORRECT WAY FOR YOUR ROLLERS TO BE INSTALLED-
Moving on to the "clutch pack" assembly, this scooter sounded like an alarm clock at idle RPM's or one of those noisy Ducati clutches. The reason being is that the backing plate on this one is loose. The three holes are hogged out / stretched out (depending on where you live) and causing it to rattle at low revs. This is becoming more common on "higher mileage" scooters. This Vespa has 13,000+ miles on it. It isn't a safety or a reliability concern but, if your clutch pack is noisy, start putting some money aside and plan on replacing it eventually. The backing plate is what the screwdriver is touching in this pic
So we've inspected the rollers, cleaned up the clutch pucks and drum, now for the belt. Drivebelts are and extremely hard wearing belt and can last up to 7000 miles or more. Vespa, being the company that it is has different replacement intervals for each model, the 300GTS Super has an extended belt replacement interval, even though it uses the same belt found on the 250. Having done countless belt services, I can recommend that you have your belt replaced or at least inspected at 6000 miles. There are people out there (on certain modern vespa forums) that swear up and down that they've gone XX,XXX miles on the original belt and it still runs like it was new. Fair enough, but remember, maintenance is cheap compared to costly repairs. Nobody wants to be waiting for a tow truck at the side of the freeway, like THIS guy did.
This GT200 belt measured out at 20.61mm, minimum thickness is 19.5mm so this belt is good for another 2000 miles or so.(The belt on this scooter was replaced once already) Obviously, you'll also want to inspect the belt for cracks in between the belt teeth.
Here's a list of MINIMUM belt thicknesses-
ET2 & LX50 17.5mm
ET4 & LX150 21.5mm
GT200, GTS250 & 300 19.5mm
Vespa drivebelts are DIRECTIONAL, make sure when you install the belt the arrows printed on the belt are facing forward and you can read the writing on it-
To reinstall/replace the belt, you need to place the belt on a level surface with the clutch pack in the middle of the belt loop, place a neatly folded rag on top of the cooling fan fins then, grab the upper pulley half and rotate it clockwise while gently pulling it towards you. (If that step is confusing, let me know and I will add a picture) The pulley half you are rotating is under tension from a spring so be careful not to get your fingers caught. Once the pulley half is held completely open, place the belt into the clutch pack, deep into the pulley and cinch the belt with either your hand or a pair of vice grips...
Set the belt/clutch pack aside and inspect the idler pulley, give it a spin, is it noisy, excessively noisy? I've never had to replace one of these so a noisy idler would be unusual.
Ready for reassembly? Let's do it! Take the variator assembly and carefully slide back onto the crankshaft. It is of utmost importance that you correctly install the variator squarely onto the crankshaft, if you mess up this step, you've just cost yourself a fortune. Slide the variator all the way home and give it a wiggle to make absolutely sure it is seated properly. Take the slider bush and make sure it is COMPLETELY CLEAN, DO NOT OIL OR GREASE IT (regardless of what you've read on any modern Vespa forum) then place it in the center of the variator, you can also take a deepsocket, slide it over the crankshaft, mate it to the slider bush and give it a few gentle taps with a soft faced mallet to make sure it is correctly installed. PERFECT-
Next, install the belt and clutch pack together, you'll want to remove the vice grip pliers to allow the belt to clear the idler pulley, try to keep the belt deep in the clutch pack pulley as this will allow you to install the variator FIXED pulley half easier.
Install the washer...
Install the variator fixed pulley half, be sure to inspect the large anti-vibration o-ring for cracks, if it's not in perfect condition, replace it. Only the GT200 uses this o-ring. It helps absorb the ringing noise made by the starter mating with the starter ring gear...
which is installed next. Make sure you line up your paint marks! Install the nut and torque to 61.2 foot pounds. (ET4, LX150 & GT200 models ONLY. GTS250 & 300 55foot pounds) If you don't have a torque wrench, buy one, you'll be glad you did, you'll use it all the time to service your Vespa. (P.S. Don't trust any mechanic that doesn't own a torque wrench.)
You are now ready to reinstall the trans. cover, make sure these two brackets are down, out of the way so they don't get sandwiched between the trans. cover and it's mating surface...
Remove the oil dipstick and refit the trans. cover. I find it goes on easiest working front to back (left to right as you're looking at the Vespa from the side). Once in place, make sure you didn't catch the above clips and replace all 10 machine screws that secure the cover. REMEMBER! DON'T FORGET YOU NEED TO MAKE SURE THE GROUND WIRE IS CONNECTED! Install the washer, then the nut to the axle shaft, then torque to 44.2 foot pounds (all common models, 50cc Vespa scooters might be different.) Replace the dipstick. You'll need this tool to help you torque the nut to the correct specs, this is the real deal Vespa factory tool, available from me or from your local dealer.
The tool in action...
The rest is easy, install chrome Vespa hubcap, secure air filter assembly and go for a road test. This job from start to finish should take you less than two hours. If there are any steps you find confusing, if you have any questions, or would like to order parts for this or any Vespa repair, please contact me directly at firstname.lastname@example.org
Thanks for reading!