'02 Zuma 50 - BBK and carburetor questions

[oppy]

Happy Memorial Day!

Installed the autotech355 BBK in my '02 Zuma the other day.  After a few break-in runs at different throttle positions, etc., I pulled the plug (BR8HS) this morning to take a look:



I think it looks pretty good, maybe a bit lean?  I do have a selection of jets on order, and I figured I'd likely have to upsize.  Looking for expert opinions!

Also, I opened up the carburetor figuring on moving the needle clip, but, for the life of me, I can't figure out how to take this one apart.  The pin on the side seems to move fairly freely but won't slide out.  I tried a paper clip on the small hole on the other side, but I didn't want to force anything.  Can someone explain how to dissassemble this?

[Zino]

Use a sewing  pin to push the pin out from the bottom picture
take pictures so you can put it back together.

Go up a jet
with stock carb I was running genuine mikunis between 85-90
I bought them from here
jetsrus.com/a_jet_kit_scooter/yamaha_50_zuma.htm

the yamaha jets you could use order from a yamaha dealer or partzilla these are the jets and part numbers i used 84 main jet 14T-14343-42-00 and a vino pilot jet 5BM-14353-23-00

The vino pilot jet is one size bigger the 84 is one size up
These jetes will get you in the same range as the 85-87 1/2 mikuni

[bigmatthew86]

I ran a factory carb with a factory 84 main jet for a few thousand miles on a sport build.

[oppy]

Thanks, Zino! I figured the pin had to come out that way, but the paper clip wasn't doing it. I'll definitely take lots of photos.

I'll upsize the jet and see how it runs.

I do have a Yasuni Z pipe coming, so I'm guessing that'll mean one more size up once I install?

[Zino]

the z is a great pipe you will to rebalance the transmission .
the power band starts later and is narrower .
a half gram to a gram lighter in variator weights and medium or hard clutch springs will make it a snorting beast.

[oppy]

Thanks again! I installed a Polini variator kit last fall, and I'm pretty sure I used the medium spring. Don't recall which weights I used, but I do know it pulls a lot better with the sport kit installed.

[Zino]

The green springs or Yellow springs from polini is what I have used for the Yasuni R
The yellow are stiffer

[oppy]

I'll have to check the kit again, but IIRC the springs were blue with either a weight rating or description printed on them.

[Zino]

the blue is still better than stock.

What you are looking for with clutch springs is when you hit the throttle you jump off the line with power.
If you roll slow for 30 feet and then pick up speed tighter clutch springs are usually the cure .

[oppy]

I checked the kit and there were 2 blue springs with different weights printed on them. I believe I used the one that was a bit less stiff. They're definitely stiffer than stock!




I'm fairly sure I installed 5.6g rollers when I did the upgrade.

It definitely pulls hard once the clutch grabs.

EDIT - I just realized you probably meant the other springs.  Yes, those are the blue ones, which is what the kit included.

[aeroxbud]

The 28KG spring is about 40% stronger than stock. The 22KG is about 10% stiffer than stock. You can usually run the softer spring, and it works fine.
It wont heat up the CVT, or wear out as quickly. But it's personal preference really.

[Zino]

Those are contra or torque springs if the belt isn’t slipping run the softer one this cuts down on wear and tear on the transmission
The torque springs function is to down shift you after you let off the throttle and keep the belt from slipping

The clutch springs go on clutch inside the clutch bell
The stiffer they are the higher the rpm’s before they let the clutch grab