hillclimb power nonexisting

[averagehillenjoyer]

Hey! New account to this platform, long time lurker though.

My issue is with a kymco super 8 4t 50cc. Current mods are:
-72cc BBK
-737mm belt instead of 732
-unrestricted variator bushing
-5.5g rollers
and carb retuned accordingly.

I live in the mountains, so hillclimb is very important. I recently changed the variator front end, unrestricted bushing, and put a new belt in. After said procedure, my hillclimb speed dropped from 40kmh (24mph) to under 30kmh (18mph). Also it sounds like the RPMs dropped after I put in the new parts. Could this be something with the new variator? Rollers are the same, 5.5g ones.
The scooter has been a pain to climb hills with especially with 2 riders making up 130kg. I know the scooter is already heavy but shouldnt I be able to zip through hills faster especially with the current mods?

Thanks!

[pinkscoot]

Just a few questions:
What are your top RPM?
Why did you change the belt and is it the same width and angle?
Tuning a variator is a process start with this link: 49ccscoot.proboards.com/thread/951

[averagehillenjoyer]

Thanks for the tip. Belt was old and hardened rubber, started slipping a bit so i changed a new one. Opted for a slightly longer one to get maximum travel on the variator. Now I'm getting the max travel but cant climb up hills properly.. I can't give a answer on the RPMs as I don't have a tachometer, however the RPMs are significantly lower under load than with my old belt and old variator but with the same weights. I wonder if the unrestricted bushing somehow changed the gear? EDIT: belt is the same width and same angle.

[snaker]

The CVT amounts to stages of cause and effects.
The flyweight force (through engine rpm) works against any resistances to close the drive pulley sheaves.
The closed drive pulley sheaves force the belt to walk up the drive pulley.
As the belt walks up the drive pulley, it uses up length on the larger diameter, which causes it to walk down into the driven pulley.
If you changed to a longer belt, its not really walking it up the drive pulley further, but it likely isn't walking down into the driven as far as it was before.

When dealing with extra loads, the rig is going to slow down, one way or another.
The best tuned CVT will force a downshift (backshift) through the Torque Sensing to act like a lower gear and to keep the engine at power.
A poorly tuned CVT will simply cause the engine power to be overwhelmed and bog down.
Either way, the rig will slow down.

[averagehillenjoyer]

The longer belt allowed for the belt to travel on the front plates further up than the shorter belt resulting in higher top speed. Could the issue be the unrestricted bushing if the cvt front wants to keep closing all the way resulting in higher gearing?

[FrankenMech]

You need a tach to tune a CVT.

[aeroxbud]

How is the new bushing not restricted? Has it got no spacer built in like this?


Or is it a different length?
If the new belt is too long. It won't go all the way into the variator to get a low gear.

[averagehillenjoyer]

Exactly so, the bushings are the same length, one without the thick spacer though.