New to scooters - help with 2008 Zuma 50

[bacon]

Hi All, 

New to the scooter world but have had many motorcycles in my life.  Picked up a 2008 Zuma 50 with 5k miles and have a few questions for the group. It wont start on it's own, but with the smallest sniff of starting fluid it takes off and seems to run well.  Checked compression and it seemed low at 90psi, so I pulled the cylinder and reeds.  Reeds looked good and aside from some really minor scuff marks in the cylinder (cross-hatch still visible) everything looks good.  The only thing that seemed weird is that there are 4 piston rings...two per slot.  It almost looks like the backers for an oil ring on a 4-stroke so im not sure if these are stock or not.

So the questions are:

- Should I try to find some stock rings?  are mine aftermarket or shot?
- Should I replace the cylinder with an aftermarket 49cc setup?
- If I go with a 70cc, what carb ajustments need to be made?  I dont intend to change exhaust or mod the hell out of this thing.
- Any ideas on the cold start issues?  The choke solenoid seems to work (extends slowly when I give it 12v).  Intake and plug look wet when I take them out.

Basically what would you do in my situation?  I just want a ridable little scooter - nothing crazy.  I have my big bike for speed.

Thanks for the help

[aeroxbud]

It sounds like it has an aftermarket kit, or at least piston.
Naraku did a kit where the bottom ring had a back ring to go behind the piston ring. But only on the bottom.
When I looked at prices for a replacement piston. It was nearly as much as a full standard replacement kit over here.
It was a no brainer to replace everything. If you have low compression, that might be the way to go.
What did the ring gaps look like?I
Unless you want to start playing with the jetting. I would probably leave it stock.
On the 2008 Zuma, the throttle doesn't open fully. You can do this simple throttle mod to give you more power. zumasrus.com/zdox/ztip6.html

[bacon]

I'm not opposed to jetting, I just don't want to do a million swaps - hoping someone could get me close off the bat. Do I need a new carb to run a 70cc with stock pipe or can I run the stock carb with a 95 main jet? Are there benefits to aftermarket carb? Anyone make a reputable kit that includes cylinder, carb, and exhaust?

 I took the top set of rings off but they looked the same as the bottom. They looked good but I haven't measured gap yet. Cylinder looked original - kind of rusty on the outside, has 49cc cast into it. Cast iron by weight.

[Zino]

You can run stock carb when you go to a sport level kit

I used mikuni jets in the 85 -90 range 95 was too rich
jetsrus.com/a_jet_kit_scooter/yamaha_50_zuma.htm

I run stock carbs currently on my Yamaha vinos with malossi sports and malossi wild lion street pipes.
with kit street pipe and variator I push past 50 mph with a wide power band

What's your budget and goals will drive your kit pipe and carb combo

[pili]

Zino is the man on this. If you leave the stock pipe on I found an 82 main jet which is available from Yamaha for about $5,and maybe a 46 pilot (stock is 44) which is also available will set your stock carb well to run a 70cc kit. I like the Malossi Sport cast iron kit and understand the Polini cast kit is good too. It should be very close there you can fine tune the idle with the air screw. The difference will put a smile on your face.

[bacon]

Ive read that the needle is not adjustable on my unit and that one from the earlier version will work. If I order the earlier parts, do I need the whole cap asm or just the needle bits? Which parts from the attached schematic would I need?

Will need adjustment even be needed with just a BBK and no other mods? Does it make sense to try with the stock needle setup first and then swap parts if needed?

[Zino]

For a sport level build with a street pipe or stock pipe 
The stock carbs only needs small adjustments 

you can get by with the non adjustable needle
A fatter main jet will do most of the work
If you get the 46 pilot that will richen the whole throttle range

you might have to modify the carb so the throttle opens all the way
www.zumasrus.com/zdox/zprod14.html