Greetings from the Granite State
 

Last Summer I came across a deal on a 2002 Zuma, which I bought from the original owner for $400, with 4200 miles on it. He's an older guy who lives at a campground from May - September and hadn't ridden it much since he bought a golf cart, so it pretty much sat unused for a few years. A buddy of mine heard it was for sale, so he passed the tip onto me. I stopped by to check it out, although it had no battery, it fired-up pretty quick with the kick starter, so I took it for a test ride. It sounded good and ran good, so I made the deal and loaded it onto my trailer. And that's how I became a Zuma owner.
I put in a battery and rode it around the lakes region on the weekends for the rest of the Summer. In the Fall I replaced the dryrotted OEM (2001 date coded) tires with a set of Michelin Reggaes, added a side kickstand and did the headlight wiring mod. Since the riding season is rather short up here, the Zuma has been mostly sitting in the shed for the last six months. But now that it's getting warmer again, I took it for a blast around the neighborhood a few weeks ago to blow the cobwebs out of it.
It does about 37-38 mph flat out, which isn't too shabby for 50cc, but most of the roads around where I live are posted 40-50 mph, so it's a bit dangerous if I want to go somewhere beyond my neighborhood and can't keep up with traffic.
I did some research and found a lot of performance parts available for these. I finally decided on a complete NCY 72cc kit with exhaust, clutch, variator and jets, from ZumasRus. Although the kit didn't come with any instructions, I watched some YouTube videos to help me get an understanding of what was to be expected. I have a background in mechanics, but haven't worked on a two-stroke since I rebuilt my old Kawasaki 125 dirt bike engine back in the 80's.
Anyway, I got it all done last Sunday, did the cylinder and exhaust swap first, cleaned the carb and installed a #95 main jet. The OEM jet was a #80. One of the videos I watched suggested using #95 as a starting point, so that's what I did. It fired right up, which was reassuring, then I took it for a blast. (without the air cleaner) I could feel the extra power immediately off the line, it bogged a bit in the mid range, but took off again when the revs came up. Pretty soon I had buried the speedometer, so I knew I had gained at least another 5-7 mph in top speed.
Feeling pretty good about it, I proceeded to do the transmission part of the conversion. When I got that done, and had everything all back together (with the OEM air filter installed) I took it for another test ride. Big disappointment. I couldn't get it to rev up high and the top speed was just under 30. Anyway, I ran out of time and daylight, so I put it away until I can mess with it again. I'm going to try running it without the air filter because it seemed like the engine was starving for air. I ordered an aftermarket K&M style filter, which should be here by next weekend.
Anyway, I'll search around in here for the right area to ask my questions about carb tuning and such.

I would suggest Zuma Forums but the site is dead, especially in the 50cc section. Zumas R Us have been around for a long time, and you should email them and ask for suggestions on the roller weights in regards to you tune and body weight. They should be able to point you in the right direction. It sounds like your transmission tune is way off, and it needs to be dialed in. I hate tuning transmissions and bug a friend at work for help when needed. One day I will get around to doing my 98 Zuma. I have a Malossi cast 70cc, free flow intake, 17.5 Stage 6 carb, carbon reed pedals, Malossi Wild Lion exhaust, Multivar 2000 variator, NCY secondary sheave (my OEM is damaged) and all related jets, rollers and springs. I despise pod filters but did order a clear OEM style air box. Just lazy and have yet to get around to mess with it. Using a Lamda exhaust reader along with plug seat temp and air/fuel readings to tune. Hate soft seizes from poor jetting and flat spots from bad transmission tuning. I just sold a 2001 Zuma for $400. Hit 45mph solid. Has a Leo Vince ZX-R exhaust, Multivar 2000 variator, free flow intake, carbon reeds, up jetted on stock carb, white torque spring and some minor port work done.

"I came across a deal on a 2002 Zuma"

Ahhh. A hot little 2 stroke. Well done. Welcome to the forum.

Welcome to ScootDawg!

Where do you live in the Granite State? I lived in Ports for six yrs & Barrington (Rt 125) for 38 yrs Riding was much better there . My wife wanted to move to Fla & the riding sucks! Riding in the mts was great & a lot safer then here. :ugh: Irish:scoot::nuts:

I'm in Hudson, close to Nashua. I work in Mass so the commute isn't too brutal. I used to go deer hunting in Barrington and have relatives in the Milton-Rochester area. I have a camp up in Ossipee and go ATV'ing up in the Gorham-Berlin area.

I've seen deer in my backyard in Barrington! Also Turkey ,Moose, Woodchucks, Bear, etc. I lived (approx.) on the Barrington-Rochester line on Rte. 125 next to JUST-OIL. Irish

Hi sc00ter, thanks for the reply.
The power loss wasn't from the transmission kit, it was caused by reusing the stock airbox, the engine couldn't breath. The new K&N filter cured that, but I ran into another problem which I posted about here:

http://www.scootdawg.net/showthread.php?t=56191

Watch you plug color! Do plug chops on the regular till you dial it in! Every big bore Zuma we build (friend and I love these things) we get a minimum 55mph with the stock airbox. Well, we run a gear up in the reduction box also-15/50 ratio. Anyways, my friend runs a rear facing pod filter and he had the worst time getting the jetting correct. Then, we got caught in the rain so he has the rain approved slip on cover over it now. They also make a over-sized factory direct replacement airbox. Oversea's and Mexico get the 100cc 2 stroke bug-eye Zumas, thats one of the only performance related things that directly transfer over, the airbox. I did a Stage 1 build on my pre-bug. Hit 45mph but didnt like the exhaust. If you get a expansion chamber type exhaust, the Yasuni R is a great value-both with a 50cc and 70cc. The "Z" series sucks. I bought a Z series...... Had a R series Yasuni on my old 70cc 2008 bug-eye Zuma. Worked great and not to loud either.