1990 Zuma build

[derrick760]

I just started a rebuild of a 1990 Zuma 50cc.  Previous top end was done, I think I ran it lean because of a crank seal leak.  The only mod from the old build is final drive gear change.  The new build is with the following parts: 


Polini 21mm Carb Kit '89-'01 Prebug Zuma



This full kit includes the "Big Valve" performance intake, Polini 21mm CP carb, remote choke cable kit, and open air filter.



Polini Pilot Jets / Slow Jets for CP Carb 17-24mm Evo



PWK oko Polini main jet kit 100-118



Malossi "Multivar" Variator Minarelli



Polini ZUMA belt minarelli



Malossi fly clutch bell kit DIO ZUMA



Yamaha Minarelli Center Contra Springs (yellow)



Malossi Sport Delta/Fly Clutch Springs



Stage6 Pro Replica MK2 Exhausts For Vertical, Horizontal Minarelli



72CC big bore kit Polini Contessa



OEM Yamaha 10mm Wrist Pin Bearing



Polini Zuma crank seals

I have a couple of questions,  where should I start for jetting for bother the main and slow jets?  I know every bike is different but just looking for a good starting point.  the second question is what spring set should I start with on the clutch springs? 

[yambw’s]

Get some pics up..sounds sweet

[woodini]

1990 🤙🏽
I love antiques

[Zino]

With that pipe If it is the newest version it is a Yasuni R in Stage 6 packaging
You will need the stiffest springs
Yellows probably wont engage high enough and be just ok The Malossi Reds is what i would run with Fly Clutch paired with Yasuni R.

As Far as Jetting
Open Filter or Airbox
For The Main Jet
The pilot jets are usually close to 40

One of the Pwk Tuners needs to chime in Kenho is running stock air box with a 21mm PWK .

[derrick760]

Jul 5, 2021 2:49:13 GMT -5 woodini said:

1990 🤙🏽
I love antiques



And to think the crank seals dried out after just 31 years.

[derrick760]

Jul 5, 2021 2:28:25 GMT -5 yambw’s said:

Get some pics up..sounds sweet

I will get a few today with it on my makeshift lift, consisting of two dirt bike stands 

[aeroxbud]

Nice build. Will be a lot of fun to ride.

[Zino]

Ingram is also running a zuma with a 21mm pwk carb he has his jetting in his signature
I would read his build thread to help you dial in yours .

49ccscoot.proboards.com/thread/27374/ingrams-2005-yamaha-zuma-build

here is kenho zuma build

49ccscoot.proboards.com/thread/25916/kens-08-zumba

between those 2 guys they could give you tips on your carb

[derrick760]

Jul 5, 2021 22:44:09 GMT -5 Zino said:

Ingram is also running a zuma with a 21mm pwk carb he has his jetting in his signature
I would read his build thread to help you dial in yours .

49ccscoot.proboards.com/thread/27374/ingrams-2005-yamaha-zuma-build

here is kenho zuma build

49ccscoot.proboards.com/thread/25916/kens-08-zumba

between those 2 guys they could give you tips on your carb

This is exactly what I was looking for, the only big thing is I am running a vertical engine. 

[derrick760]

I didn't get it all done over the weekend, I needed a few additional parts to hookup the factory choke lever to the 21mm pwk carb. I got the new cable in yesterday now time to jet the carb and start reassembly

[Zino]

i have jetted both the vertical and horizontal zumas with a 19mm dellorto
I ended up at the same jetting or at least within one jet with the airboxes.

[derrick760]

So I got the thing together enough to run, not all the body panels are the rear light is on. Any way I talked to the guys at the scooter swap shop where I purchased everything and went with a 108 and 38 jets near the others with a 110 and 40. It smoked a bit for the first couple minutes then cleared up. The issue now is it has no power and bogs just before it would normaly start to rev up the clutch just starts to engage then nothing. Could the plug just of fouled from the smokey first start?

[chadbullet]

Definitely worth the time it takes to pull the plug and check it.

[derrick760]

Jul 11, 2021 18:03:23 GMT -5 chadbullet said:

Definitely worth the time it takes to pull the plug and check it.

Pulled the plug, it didnt look bad, cleaned it in the sand blaster and carb cleaner, it looks good now. No change in performance 

[derrick760]

so changed the jets to 40 and 110, It feels like it never goes like it should, slower than stock on acceleration and stock carb 

Moving up to a 112 next