having fun on a french moped. hence riding in the wrong lane.
having fun on a french moped. hence riding in the wrong lane.
You will always slip with an er3. That’s the point. That’s how the “clutch” action works. If you slip all the time then you’re either not getting enough spring resistance to give the tension on the belt that’s needed (most likely as 1000 is the weakest spring available for scooter setups) or your weights aren’t heavy enough..... but it’s your spring I’m pretty sure. That’s why a launch lever and/or a stronger spring/gas shock is whats needed
Your belt length isn’t the issue btw. A shorter belt just gives you more preload on the spring. You’re spinning your wheels on the wrong thing.
It’s all simple physics.
Do you notice that after you decelerate you aren’t in the power anymore? With a lever you just hold your foot on it and boom, back in the power. You need it frankly
that video was with the original clutch and pulley. with starter arms removed and rivets added to shorten the clutch leaves so as to bite/stall higher. the engine has low rev porting for rideability. all i want is 6500- 7000 bite/stall point.
i did modify a clutch like yours with springs on the leaves but they just wear out in no time with all that spinning.
i can add more preload to my contra spring cos i made it adjustable so will try it on max preload but it looks like i need a launch lever and a stronger spring.
does the business end of the lever contact the engine or the last coil or two of the spring?
No you most likely cannot add enough preload. I’ll tell you why.
The scooter contra is short compared to other moby style springs. You will coilbind the spring much before you get to full variation. That’s why I suggested to use a stronger spring.
I battled with lack of variation on my moby and it all came down to the coils bumping into each other before the engine was done variating, leaving a lot of top speed unavailable. If top speed isn’t an issue than nbd. But yeah, Unless you use close to the full length of the scooter contra, you’ll coilbind before even getting close to full variation.
2 springs welded/fastened together? or 1 and a half ?
my belt is slipping on the er3 cheeks. the belt seems to be too sharp an angle for the cheeks so that only the top 2 or 3 mm is in contact. i have big rubber marks on the cheeks and the belt is red hot.
just tried a few test runs.
belt angle by alan jackson, on Flickr
if i fit too short a belt on, so the spring is under more preload there is only 30mm of spring movement and there is no goat. but the belt slips under wot.
belt slip by alan jackson, on Flickr
I’ve told you your issues.
Get a stronger spring (1500-2000 spring) and a launch lever, then retune. You could try to add an extra spring but you don’t have the room so GET A STRONGER SPRING LOL. I’m using a stronger spring than you are with my 50cc moby.
The belt’s side angles not fitting well is because er3 has steeper cheeks than most standard V belts to allow more variation at fully closed. They tend to eat belts, especially when you don’t have enough tension on the belt due to a weak spring.
French style bikes want to get as much variation as possible, and often cheek angles vs belt angles don’t match to achieve that end goal. With a baby weak spring those few mm of belt will slip like crazy. With a stronger spring it will grab. Slip creates heat. With a launch lever you can manually add more tension without a stronger spring.
stronger spring it is. then a launch lever.
im just wondering if i can shape a belt as well, like you did. but to fit the angles ot the er3
it isnt gonna hurt if there is more contact area
only 2 or 3 mm is not logical.
Don’t do it.
Trust me. The belt will wear into the shape and once it wear in, shit gets weird.
1st off, steep cheeks aren’t a great way to variate. But it’s required with frenchies cuz it’s the only way to get big variation (cheeks coming together as much as possible)
The problem with matching to a steep cheek is this. Mismatched belt to cheek is fine, shifts great. If you match steep cheek angle to belt angle, the belt will not shift well. It resists shift as it does not want to move up the cheek. I have done extensive testing with this. One can use mismatched cheeks like a steepy on one side then a less steep 15deg on the other. The 15 standard side will allow the belt to climb easily and shift well, with the steep side pushing the belt up that stock angle side. Now if both are steep, and the belt is steep too, the belt just gets pinched and can’t move easily. Belts don’t like to climb vertical walls. It’s simple physics.
However, the limitations with the archaic French shift design demands these accommodations if you want the large variation so you can run very short gearing but variate very far. Even 2mm difference in belt height at top variation means many more mph.
This knowledge sounds obvious in hindsight, but I tested multiple cheek angles over the course of a few years from 7.5deg-16 deg. And then tested belts matching those angles and unmatched. It taught me a lot about variation.
Another interesting note to this:
A clutch pulley works great for French bikes because that thin belt grip area wont be abused and slip at the vari boss, the large pulley with its exceptional grip is the main grip point, the fixed non clutch er3 or other vari just spins the pulley up and the pulley is where the clutch engagement happens with little chance of slip
thanks for that very informative reply. now you explain it i can see the disadvantave of a belt same angle as the cheeks and its reluctance to move outwards. i bought an er86 and found it was no good below 8k rpm even with weights and light springs. i fitted it to a smaller pulley to make it spin faster and it works and bites at low revs on my paloma, until it meets the power of my parmakit motor. ive fitted the original clutch/variator and pulley back on and it seems tame now on take off. cant believe the difference. hardly any spring needed and the belt doesnt slip. im awaiting a stronger spring and couldnt resist 2 x 200N gas struts for £10 off ebay.
Well good. It’s all experimentation but it’s handy to read the actual physics behind this stuff.
Fine tuning performance French bikes is all about playing with the variables. It’s my only opportunity to have a moped act more like a manual so I prefer tuning for that, the act of seeing rpm climb with use of the lever then dumping it kinda slingshots you forward which is my fav thing in the world
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