Variator, roller weights and contra spring mechanics for dummies! Learn how it works

[evoboy]

wasnt sure where to put this, but it concerns the topic.

i have a stock sr with a minarelli 50cc ac engine.

the problem im having is that it seems to be shifting into lower gear as soon as a very small even bump in the road occurs.

im currently running 30% stiffer contra spring, 5g weights, and a leo zx pipe, the bike has also had the washer removed.

could my contra spring be too strong? as it seems to hit a hill and jsut shifts down into low gear too early, the engine also wont over rev even on a small downhill.

im determind to get this scoot running right if it kills me!

[Berlin]

This is a fantastic post. Excellent information, superbly presented.

We have just bought a 1991 BWizz (CW1) moded for our son and this information has proved very beneficial in him learning how it works.

When we bought it I test rode it and could get the speed up to 27.5 mph. Now I'm a big guy at 250lbs so i put the speed down to my weight. However it felt like something was "slipping" at 27mph. Like the variator belt was slipping.

Now my Son has had a try it was the same thing, so it's not just my weight (he's significantly lighter ) . It feels like someone is hanging on to the bike at 27.5 mph and holding it back. Also, when travelling downhill it still feels like there's someone hanging on the back slowing it down. It just sat at 27.5 mph which I thought was odd. there was no change in Engine pitch or RPM.

There didn't seem to be a restrictor washer in the variator (like the one shown in the other very excellent derestriction thread) but there is some Oil in the cover of the variator that looks like it has come from a weep on the Oil pipe from the carb. This may or may not be on the belt.

The gentleman in my local Yamaha shop informs me that this moped should be good for 60mph when derestricted so we know somethings not quite right. We were informed that the bile had had new Weights installed just before we bought it. The carb doesn't look to have any restriction in it and we haven't had the pipe off to check the exhaust yet. If anything the bike is running a little rich and "wooly" which I'll look at next.

Could anyone advise whether we are right to look at the variator or the Clutch pads for the answer to this "idiosyncracy" ?

Thanks, in advance,

Carl

[MikeT]

Vario, yes, clutch pads... unless it is slipping, no.

A couple of questions...

Does it get up to its (current) top speed relatively quickly?

Does it do it in one smooth action or does it feel like it is having a couple of bites at the cherry? i.e. does it smoothly accelerate at the same 'rate' as the revs climb?

Does it hit peak revs quickly? and then the speed increases as the vario catches up?

Does it feel like it is at peak power or is it struggling?

On trailing throttle from top speed, are there any vibrations or juddering coming from the transmission or is it all as smooth as silk and revs smoothly reduce in line with road speed?

Can you weigh the weights? Or are they marked with a weight?

And 60mph is fairly optimistic of your mechanic... it is possible, but it will take a bit of work... 45+ is eminently achievable, though. Are you sure it is a 1991? How many miles... it may just be very tired...

[Berlin]

Hi Mike,
Thanks for your reply. I've added the answers below inside the quote...

Vario, yes, clutch pads... unless it is slipping, no.

A couple of questions...

Does it get up to its (current) top speed relatively quickly?

Yes, Its pulls off very cleanly and feels strong

Does it do it in one smooth action or does it feel like it is having a couple of bites at the cherry? i.e. does it smoothly accelerate at the same 'rate' as the revs climb?

As far as I can feel, yes.

Does it hit peak revs quickly? and then the speed increases as the vario catches up?

Not sure on this one, I would suspect it's something I'd notice so i don't suppose so.

Does it feel like it is at peak power or is it struggling?

It feels like it's going well. although as I said it could be rich as it's a little "wooly" but then I'm used to fast revving big bikes. It'll hold the same 27.5 mph at 3/4 throttle., Opening the throttle further on the flat achieves nothing.

On trailing throttle from top speed, are there any vibrations or juddering coming from the transmission or is it all as smooth as silk and revs smoothly reduce in line with road speed?

No vibrations. it just feels like someone is holding it back. It feels like it's "electronically" limited to 27.5mph Like there is something reducing power instead of restricting it (unlikely, I know). . I'm struggling to explain it (I'm a chemical engineer and ex bike racer so I know my two and four stroke engines and general mechanical principles.)
The reason 27.5 is strange is that going up hill, down hill into or with the wind it still does 27.5 mph. Surely if it were a power issue it would drop into the wind and up hill. And I'd expect it to run away down hill but it doesn't it's like it's trailing the brakes without you doing so.

Can you weigh the weights? Or are they marked with a weight?

I've not had them out but could take it apart at the weekend.

And 60mph is fairly optimistic of your mechanic... it is possible, but it will take a bit of work... 45+ is eminently achievable, though. Are you sure it is a 1991? How many miles... it may just be very tired...

It is a 1991 and has aledgedly done 4000 miles although this is probably a "little" off. It feels fresh and it feels like there's a lot of go left in it yet. The plug will be out at the weekend so i can see what's going on with the mixture.

[MikeT]

So it is a 1991 air-cooled with 4K miles... and the engine feels strong, the tranny isn;t grabbing or otherwise misbehaving...

It may be that in those early days it had a rev limit built into the CDI...

So no matter what you do, you can't get above the limit and therefore it 'qualifies' as a moped...

An aftermarket CDI is going to cost a few quid... if you are willing to take the chance, check for a bridge the same as for the RS50...

[mikethebikeSR50]

Hi, ive got an aprilia sr 50 r 2007 model and ive bought a technigas exhaust, do you know exactly what weight rollers a springs i would need because when i put the exhaust on a few months ago the bike had a flat spot at 25-20mph.
thanks a lot
mike

[Evans-2006]

No weights with the exhaust?
Try 6.5 gram and get a stiffer malossi clutch spring, see how u go

[mikethebikeSR50]

So if i get some 6.5 gram weights the flat spot will go and those clutch springs, where could i get them from? and what weight?
thanks
mike

[Modular Overrev]

i have an Aerox R 50 LC with the following mods;

Leo Vinci TT pipe
Mikuni 16mm carb from a BWS100
Polini 0,25mm carbonfiber reeds
Ueno Demon vario
Malossi torque driver
Malossi green clutchsprings
Malossi yellow vario spring

airbox is from a Yamaha Jog which have a bigger intake snorkel, the original airbox was gone when i bought it, the engine was freshened up with new piston & rings & put thicker cilinder base gaskets so the all the ports are fully open when the piston is at BDC.

it runs pretty strong for a 50cc engine with untuned ports, the speedo cable is gone so i don't know how fast it really is doing but from my experience in tuning dragscooters it reaches an estimated topspeed of 85 to 90kmh.

to get 100kmh (62mph) is not impossible with a stock 50cc cilinder but it will require some serious tuning & supporting parts like a full circle crankshaft, carbonfiber reeds, taller gearing, pipe, vario, torque driver, bigger carb & some porting.

stock dellorto carb is only 12mm which is pretty restrictive so no matter how much modding you do with the engine the stock carb has to go that's why i swapped it out with a 16mm carb from a BWS100.

the easy way to get 100kmh is to install a 70cc midrace cilinder (MHR Replica, MK SP2, Polini Corsa), Yasuni R pipe or any equivalent, 16mm & up carb (best results with a 19 to 21mm carb), 13/44 gear kit, vario kit, clutchsprings & a torque driver.

those are the mods i am planning for my aerox but my goal is to hit 120kmh (70mph) for real, this will be a street/touring based setup which i also plan to use on the track.

[Frankie_aerox50]

Hey Guys,

I am newbie here thou i have just made some radical changes to my Yamaha Aerox 50cc 06 scooter:

Gianelli Nxt Exhaust Pipe
Mallossi Multivaritor Kit includes:

New Variator
New Roller Weights
Red Spring
Green Clutch Springs

Now its been installed tonight and took it for a ride and noticed a few changes:

A. she is no more boggy downlow in the rev range.... seems to rev more and hold the revs

B. my top end speed has been reduced now before i couled easy get 85-90km with Stock variator and clutch spring setup and re-strictor washer in the variator but i had a ginalelli pipe on for a few weeks.

Now i only can get 70-80 on the flats and it really takes a while to get to the 80kmph - what can be done to fix this?

My main concern is how can i get more top end to back where i was?

Should i remove the GREEN clutch springs? - and replaced back with stand ones?

if anyone can help, would be awesome... cheers

Frankie

[gazeddy]

wrong topic

[kd sweety]

my variator is a complete bitch, is it possible it has a left handed thread? its a 2006 piaggio NRG DT btw

[MaRRko]

Hey guys im newbie so can some expert PLEASE help me I have aprilia sr 50 LC Minarelli 1998 so can you PLEASE tell me wich malossi contra spring (white,yelow or red) can i put for best performance. I have malossi clutch with white springs and i also have giannelli aluminium exhaust and malossi multivar but i don't know wich weight of rollers to put in. Otherwise said PLEASE help me tune my transmission! thanks.

[aurelius]

anyone know where in USA to buy the 2 Buzzetti tools mentioned on page 3 of this thread?

Impact wrenches can be quite expansive.

Luckely there are these incredible handy Buzzetti tools, that makes unbolting/tightening the variator/clutch/big pully screw a piece of cake:

Clutch:



hard to see, but you can see 2 "studs" that lock into the clutchbell's holes. This locks up the rear variator axle. Now just use your socket wrench and...DONE.

Now you probably also noticed the big "Hexagon" shape. Yes this fits exactly over that big and flat TQ screw. Again making bolting/unbolting a 1 minute job.

variator:

(bit small)
(copy/paste link in new browser window)

http://www.easyparts.nl/partpics/01087899.jpg

This locks onto that tooted ring (on the crankshaft) that the small kickstarter gear locks on to when kickstarting.
This locks up the variator/crankshaft.

Again, get your socket wrench and unbolting and torqueing it up is soooo easy.


And for those people that don't give anything about there stuff, there's always the pistonlock:



This screws into your sparkplug hole, blocking the piston.

Of course with a soft(er) aluminium piston, when applying (lot's of) torque on the crankshaft nut, you risc damaging your piston.

I have used it years ago (without any damage) before these cool Buzzetti tools existed, and before I knew anything about scooters.

[reecebuy]

i have a sr 50 08 carbed i was wondering how many restrictors are there in it ?
i have taken out the variator restrictor what else is there?
thanks allot
Reece