Bbk installed and jetted. Now what?

[jodaddy]

4 yrs ago I installed a malossi 70cc kit and one step lighter rollers. Great in the flats but still hated hills. Fast forward to present. Installed the stock head and tried just 3 of the stock rollers in the name of science. Now we’re getting somewhere. Before I order the lightest rollers possible, is there something else like lighter contra spring or clutch springs that I should try first? All the power and torque is in the upper revs so I need this motor to spool up quick to move my 200lbs up the hills. Thanks much. Joe

[245luigi]

Usually you go for one higher contra and clutch springs. There is a combination of factors to make the engine spool up quick. Lighter rollers allow for higher rpm, harder clutch springs means the clutch will grab at higher rpm. I would not order the lightest rollers possible. Try and get the prima roller tuning kit and actually figure out which rollers are best for you

[jodaddy]

Aug 21, 2024 11:10:20 GMT -5 245luigi said:

Usually you go for one higher contra and clutch springs. There is a combination of factors to make the engine spool up quick. Lighter rollers allow for higher rpm, harder clutch springs means the clutch will grab at higher rpm. I would not order the lightest rollers possible. Try and get the prima roller tuning kit and actually figure out which rollers are best for you

At present all the cvt stuff is stock 50cc China stuff minus the rollers and belt. What rpm is generally stock? Seems like the options are 1000, 1500, and 2000 rpms for aftermarket stuff Thanks. Joe

[jodaddy]

Got the 1000 and 1500 clutch springs on order. That should get me started.

[aeroxbud]

If you fit a too hard contra spring. You will have to use heavier rollers to counteract it. Just something to be aware of.

[245luigi]

Aug 22, 2024 9:06:18 GMT -5 jodaddy said:

Got the 1000 and 1500 clutch springs on order. That should get me started.

now you are getting it. This is just the beginning ha

[jodaddy]

I think I may have the wrong belt and it’s creating drag. Which in turn is engaging the clutch earlier. I bought this scoot with a blown up belt and just replaced it with one for a Minarelli jog. I’m thinking it’s either too wide or has the wrong pitch or both. Since I can’t find specs on the stock belt to save my life, is there something I could measure like pulley angle or distance between the closed pulleys to figure this out? Thanks. Joe

[broyager]

What scooter is it? They are all different..

These are my notes on Jog belts, if it's relevant


Both 3KJ and 5SU are 772mm long, or thereabouts. This is pretty far off the 792 which I've come to understand is the standard length.

Actual model numbers are 5SU9 (5BM) (CV50) and 4CGC (3KJ) (CY50).

They both have identical wear patterns on their variators, and indicate about 9mm of unused travel.. so it seems pretty safe to assume that the belts are used as a restriction, so they can be sold as a moped (50kmh max), at least in NZ.

Webike in Japan is my go to for cheap shipping, and in tsimi's post in a belt thread for jogs listed;

49ccscoot.proboards.com/post/354255/thread
KN企画 (KN Kikaku) gave me this list via e-mail when I was looking for a belt for my Prebug.

Long case

7019-SHORT-NS 17.7mm / 750mm
7019-L-SS 17.7mm / 762mm
7019-SS 17.7mm / 757mm

Short case

Stock 16.8 / 793mm
Kitaco 16.8mm / 796mm
7020-SS 16.8mm / 800mm
7020-M-SS 16.8mm / 803mm
7020-L-SS 16.8mm / 806mm

This lines up with the local parts shop (https://scootling.co.nz/) who sell the 7020-SS as a stock but upgraded belt for CV50 and the longer 7020-L-SS belt for modified jogs (aftermarket variators and 90cc versions), with the warning that stock scooters using that belt maybe seem or go slower. They also sell a stock item with the provided measurements of 792-16.6-30.

I might go for the 7020-SS considering I'll re-use the stock variator and clutch (largely)