Right guys, I've been looking all over the internet to try and figure out what Clutch Springs actually do in a 'twist and go' moped. And how different strengths of clutch springs can change the way the bike behaves. The reason for this is because I will be getting a new variator and may need some new clutch springs.
pretty simple to be honest bud the clutch is centrifugal, as the rpms increase the springs stretch and allow the shoes to contact the clutch bell. Stock springs will begin to stretch at low rpms and will be in full contact (fully engaged) way below the power band. Aftermarket ones are stiffer, most will state the rpm range they begin to stretch to the rpm they are fully stretched and fully engaged Now for a 2 stroke with a performance pipe etc all the power is being shiffted to the high rpms. into the bikes powerband, meaning low down power is lost. So you need stiffer springs to keep the clutch in until higher revs where the power is. The stiffer springs i have fitted to my aerox start to engage at 4 and are fully engaged at 6, still below my bikes powerband but higher then stock which aids take off. The next spring up for me begins at 6 and is fully out at 8, i will give these a try when i get a chance but this may cause them to engage a little too late and as such i will loose power as it will rev past the powerband, as for mixing springs this could be a way to get an inbetween spring rate almost like mixxing rollers. However the softest spring will always engage first and the shoe it is attached to will wear faster. in simple terms, the softer the spring the more gentle the take off. slower and smoother, the harder the springs the faster and sharper the take off. but not all stiff springs will help your bike and may cause it to simply rev loads and not really move haha
Nice! Great explanation! Thank you! I have just been looking around for a good definition and that has solved everything I needed! Nice one!
I´ve just read your post on the clutch springs, and had a couple of questions.... Firstly, I bought a used Yamaha neos nearly 2 months ago and I´m tackling some performance issues. I´m getting a new variator, not sure which but I think I´ll set my focus on a polini. Now, I´m not trying to create a superscooter, I just want good solid performance a legal top speed (in Denmark that´s 45km/h if you have a normal car license) is quite acceptable, but what I´m most interested in is a setup that will fly me up hills. Any suggestions to which variator , contra spring and clutch springs I should look for would be an enormous help. Cheers, Jools
I´ve got a funny feeling I´m going to have to replace the clutch springs and pads because strangely enough today I could hear a kind of grinding noise coming from cvt case The last bit of info I need is really about the torque spring. Does the torque spring have to be rated at the the same rpm as the 3 other springs? Or is this one of those things that people play around with until they get the right combi for their set up. Cheers and thanks again
Thanks Merlin, I did see it before but it doesn´t actually answer my question. I try and explain it more clearly...I´m talking about the big spring and not the 3 smaller ones ( I believe this is called the torque spring but I may be wrong) anyway, the question is...if I buy a BIG spring which is rated at 1500rpm instead of a 1000rpm spring will this enhance hill performance? Cheers
The big spring is called the contra spring, it's completely separate from the little set of clutch springs. If the engine starts to labour on a hill, it will effectively vary the gear ratio to raise the engine revs by 1500 RPM and hopefully get you back in the power band. It's like changing to a lower gear on a normal geared bike.
Excellent, I´m getting very close to understanding this . So, if I want better performance on hills and I´m using a 1000rpm spring which is most probably several years old and therefore probably more like 10rpm....then a 1500rpm should give me what I want if I use a standard clutch set up but slightly lighter rollers than stock???
By God, You guys are reminding me why it may not have been such a good idea to have left school so early!. .
Regarding the terminology, when I first started out on this quest I was convinced it was called a contra spring but somewhere down the line people kept referring to the torque spring (I don´t believe it was on this forum) so I started to adopt that name thinking it was the common term. Now I think I´ll go back to using contra spring and if all else fails then I´ll keep it really technical and talk about the BIG springs and LITTLE springs.....
I´ve just fitted a new roller plate and 5,0g rollers (stock is 6,5g) I´ll post a picture of the old one after I´ve had my dinner. On starting it up just to see if the wheel still spins , I discover my starter relay is up the spout. Fuse was blown so I changed it and lo and behold.....(bugger)
Hey, lookin forward to the pics what happened? lo and behold what? I can't handle the suspence grabbing a beer and popcorn for this one lol
Yep, you got it The contra spring effectively makes the clutch pulley bigger by pushing it back, lowering the gear ratio, but the front roller stays where it is, as it's kept there by the rollers and the engine revs. The stronger the spring is, the more the pulley gets pushed back. Clever, huh? There is another clever little gadget called 'Twist Control' that's made by Nakaru; it's a sleeve, bearings and a ball race that replaces part of the clutch assembly and it's supposed to make for smoother 'gear changes' at the clutch end of things. How effective these are, I have yet to find out.
Merlin, looks like you really got the bug again for these 2 strokers, hmmm Must've been killing you not being able to get your hands on your boys scooter until he finished with it