jack667
Scoot Enthusiast
Posts: 190
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Post by jack667 on Sept 26, 2018 20:09:46 GMT -5
  Hi 49cc'ers! I really appreciate all the posts on this forum and the responses I've got so far on another thread here. I'm new to scooters and really excited about my Zuma! I bought it for $800 off craigslist and I'm deep into a build. The point of this project is to have a safe transport to/from school for my 140lb 15yo The commute to school is 5.5 miles over hilly roads with 45mph speed limits. People really go 50-60mph though. The hills are mostly like upside-down bell curves, and some more gradual inclines and declines. Ideally, he would maintain 45mph up and down, 50mph cruise and up to 55mph on the downhills. I've bought a bunch of stuff and have some installed. In so far: NCY tranny kit with 7g weights, yellow spring, clutch and variator Malossi Kevlar belt NCY exhaust Dellorto 17.5 carb with stock 80mm jet (for now) UNI filter in stock airbox At this point, with all above installed, it seems to run well. It cruises in the low 40s (want to be low 50s), goes up hills 35-37 (want to be 45), and goes down steepish hills in low 50s (and want to be high 50s). It's really peppy off the start. On the way, I have: 70(or 72?)cc NCY bbk, which came in a 'kit' with the other NCY stuff above. I think it's relatively cheap, ie sport/iron/2-ring Sport Airbox Doppler Intake Stage 6 Reed Cage and Venturi Jet kit - plan to try a 95 with this set-up 5g Dr Pulley Sliders Nology hot wire BR8 plug NCY rear shock Brake pads all around new front fork boots I plan to get all of the above installed this weekend or possibly next weekend. It would be great if this round of mods gets me to my goal, but if not, I think I'll need to first focus on tuning all that kit before going to gearing. I'd certainly love to hear some predictions on how it turns out with all above installed - with respect to my goals. And also some thoughts on what else to do. Lastly, I'd be very grateful for any suggestions while we perform the work above. I'll be doing most of it myself, and with my son, but the BBK will go in with some major help from a friend with a ton of 2-stroke experience. Thanks and really happy to have found this forum Jack |
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Post by ryan_ott on Sept 27, 2018 12:43:35 GMT -5
If the above is with the stock 50cc cylinder your not doing too bad. With the addition of the 70cc and some CVT tuning you should be able to reach your goal. Especially considering the light weight rider. Be sure to read through the tech articles for cylinder prep and cvt tuning. Some cylinders have really sharp ports that need to be cleaned up with a file prior to install. Also setting up the variator properly will give you the full potential of best take off and highest top speed.
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Post by geoffh on Sept 27, 2018 14:47:32 GMT -5
Jack ,I run a Yamaha jog (UK equel to Zuma) and have just a few mods running at49cc it runs a tad less than your current set up but I am not trying to get more from it.Just a few hints to help you avoid mistakes I made
Check out brake bleeding tips,they are a pain
Piston pin clips are difficult to fit check and check again
Put the piston in the right way,arrow to exhaust normally
Consider changing things in steps and take detailed note,s of their effects
Those are facts this is my opinion
Sport air box (try with the stock one first)
My scoot runs better with an old Yamaha belt
Use a variator tool and torque wrench not the power tools
Grease up the torque driver in the clutch
And remember 2t tuning is witchcraft
Geoff
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Post by jmkjr72 on Sept 27, 2018 15:58:28 GMT -5
Leave the stock air box all get your self an oem 82 and 84 main jet from yournyamaha dealer. If you look over on Zuma forums for a thread called why use the right jets it has the proper part numbers
Get rid of that belt and get an oem belt Yamaha’s have just a slightly diffrent spec even between euro and Asia models the nology wire is a waste all it does is allow you to run a non resistor plug
With that bore the stock intake flows more then enough
The oem pipe does not have the power band to hit what you you are looking for without a gear swap
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jack667
Scoot Enthusiast
Posts: 190
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Post by jack667 on Sept 27, 2018 20:16:32 GMT -5
All great advice! Thx Ryan, Geoff, and Jr!! Well, the cyl kit came in today so we were able to put it on. I had a friend come by who is a former 250cc 2-stroke vintage dirt bike nat'l champ. He's built a lot of motors so I trusted him with all the crazy clips, etc. My son took apart the body, and I took off the intake manifold with carb attached, the airbox, the exhaust, the plastic shrowd around the cyl, and then the front part of the cyl. See first couple of photos below. Is it odd that the cylinder head has those markings on it? Anyway, Wayne came by and installed the piston and cyl, and then we put it the mechanicals back on and it started right up! I then upjetted from stock on the 17.5 Dellorto (80) to 90. It's a bit smoky, and is sounds deeper. Next, putting the body stuff back on and then breaking it in. Should have that done by the weekend and a top speed run by Sunday night. Still need to install the Nology wire, airbox, intake and reeds, 5g variator weights, jet and BR8 plug. Still running a 7 for now until I can get that wire installed for the non-resitstor plug. I figure some of the stuff I bought is not going to help much, but I'm hoping it doesn't hurt. I'll do some testing with jets, air screw, etc. Checking plug. And then try the different weights. I'll probably try both airboxes... I'll post again on Sunday night when the current set up is broken in and we have some performance results, in terms of speed. Thx again for all the comments - I appreciate every piece of input! Jack      |
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Post by repherence2 on Sept 27, 2018 20:45:20 GMT -5
I have run the NCY cast iron bore with success. I thought it was pretty good. It is not on the level of a Polini corsa, but its got some grunt comparable to the Polini contessa or the Malossi sport. I tried the NCY variator, clutch, clutch springs, and contra spring. The lightened NCY clutch was pretty good but getting the red springs on the clutch shoes was a task. The NCY variator that I bought seemed like it was basically a stock replacement. The roller ramps seemed looked like it was the same as the stock unit. I switched variators to KELI, it has ramps that extended further out than the NCY unit and i feel that it shifts better than the NCY. I have used the black, yellow, and red contra spring. I actually liked the red spring in regards to going up hills. I am running a yellow now, and it doesn't pull as hard uphill as the red spring did. The drawback with the red contra is that the CVT gets really hot and the belt wears quickly. The yellow does not downshift enough for big hills and corners. Might be worthwhile to buy a main jet kit, at least that way you have an assortment of jets in incremental sizes so you can tune better. I would recommend a Cylinder Head Temp gage so that you don't end up soft seizing your new bore, just stay below 350°F.
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jack667
Scoot Enthusiast
Posts: 190
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Post by jack667 on Sept 27, 2018 20:54:34 GMT -5
time for a dumb question. Do I have the wrong rear shock? I took off the stock one (or whatever was on this scooter) and replaced it with an NCY shock that I bought from a shop, based on my scooter and year: 2008 Zuma.
The bike was on the stock center kickstand, and after taking off bottom bolt from the existing shock, the rear tire dropped to the floor.
The new shock went on without raising the rear wheel. The adjustable collars were all the way down. The rear tire is still firmly on the ground, with both bolts in the new shock.
I adjusted the collard up, quite a bit, and the tire is still on the ground. I took it off the kickstand, bounced the bike a bit - compressing the shock, and then put back up on kickstand. Rear tire still on the ground.
I can keep running the collars up, and I guess I'll do that since I don't have any other options at this point. I guess I can call the place I bought it from tomorrow...
Comments?
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Post by ryan_ott on Sept 27, 2018 21:07:42 GMT -5
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jack667
Scoot Enthusiast
Posts: 190
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Post by jack667 on Sept 27, 2018 21:26:03 GMT -5
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jack667
Scoot Enthusiast
Posts: 190
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Post by jack667 on Sept 27, 2018 21:50:27 GMT -5
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jack667
Scoot Enthusiast
Posts: 190
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Post by jack667 on Sept 28, 2018 7:42:49 GMT -5
I have run the NCY cast iron bore with success. I thought it was pretty good. It is not on the level of a Polini corsa, but its got some grunt comparable to the Polini contessa or the Malossi sport. I tried the NCY variator, clutch, clutch springs, and contra spring. The lightened NCY clutch was pretty good but getting the red springs on the clutch shoes was a task. The NCY variator that I bought seemed like it was basically a stock replacement. The roller ramps seemed looked like it was the same as the stock unit. I switched variators to KELI, it has ramps that extended further out than the NCY unit and i feel that it shifts better than the NCY. I have used the black, yellow, and red contra spring. I actually liked the red spring in regards to going up hills. I am running a yellow now, and it doesn't pull as hard uphill as the red spring did. The drawback with the red contra is that the CVT gets really hot and the belt wears quickly. The yellow does not downshift enough for big hills and corners. Might be worthwhile to buy a main jet kit, at least that way you have an assortment of jets in incremental sizes so you can tune better. I would recommend a Cylinder Head Temp gage so that you don't end up soft seizing your new bore, just stay below 350°F. Great to hear about your success with the NCY bbk! I'll check into that variator and belt, especially if I'm not getting to goals. The kit I bought came with the yellow spring so I'll stick with that, but may play with it if I need to tune. I have a main jet kit and just put in a 90, to replace the 80 that came with the dellorto 17.5 Interesting about the temp gauge! One I get all this settled, I'd like to work on the cockpit, and go with some new bars and gauges. Without doing any research yet, I feel like I'd prefer analog gauges. I suppose I'd want the stock items: speed, fuel level, and oil light, plus temp (cylinder head, anything else for temp?), and a tach. But I think that's a couple of months out, maybe a winter project. I hope I don't cook anything in the meantime. |
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jack667
Scoot Enthusiast
Posts: 190
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Post by jack667 on Sept 28, 2018 14:41:59 GMT -5
Deleted question - figured it out - never mind!
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jack667
Scoot Enthusiast
Posts: 190
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Post by jack667 on Sept 30, 2018 8:02:15 GMT -5
I would recommend a Cylinder Head Temp gage so that you don't end up soft seizing your new bore, just stay below 350°F. Hi Reph! I'm looking at CHT gauges and see the Trail Tech TTO one. Question to the 49cc gurus... Should I buy the one that connects at the spark plug for my 2T Zuma? Or is there some other one to get, that connects to a fin, or something other than the plug. Thanks in advance!! smile.amazon.com/dp/B071HKW8R9/ref=psdc_404769011_t2_B01H7QA5OKJack  |
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Post by ryan_ott on Sept 30, 2018 8:54:43 GMT -5
I think most use the TTO ring type under the plug sensor. There are chinese off brand equivalents that are backlit but trail tech handles warranty problems promptly and has a more compact meter. So it’s a toss-up.
You’ll also want a 14mm sensor
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Post by geoffh on Sept 30, 2018 9:41:01 GMT -5
Cheap and cheerfull rev counter wraps around plug wire,temp gauge on a cyl head nut I just hook them up for testing the tiny tach isn,t waterproof and the temp gauge breaks if you slam it between the seat lock (stars)but £20 all in Geoff  |
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