Limiter on Yamaha Zuma 50f

[6rant]

Hello!

I recently got a brand new 2014 Yamaha Zuma 50. This is it. It's a great little scooter and I'm really having a blast on it. There is one issue though. It seems to have a speed limiter that maxes out at around 41-42mph. On flat ground it can do 40 so theoretically I should be able to go faster than that downhill. I used to own a Honda Metropolitan that got up to 47mph going downhill. But the Zuma stops itself when I get to 40, it doesn't accelerate more even though it should be. It almost feels like the brakes are being applied slightly. Any ideas on why this is? If it's an electronic limiter, how do I remove it?

Thanks!
6rant

[Elektrey]

could be a ring in the cvt preventing it from fully closing and attaining highest gear.
could be rev limited by CDI

if it will get up to 40 on a flat ground but wont go past 40 going downhill it sounds like the second.

[moofus02]

The computer retards ignition timing to kill power to limit speed. Aftermarket unlimited rpm ignition is still limited only adds 250 rpm. Keeps the motor togather. Check with scootertuning.ca for a gear up kit. They make enough power to run true mid to high 40's with the right gear

Sent from my SPH-L720 using proboards

[6rant]

May 5, 2015 14:58:00 GMT -5 Elektrey said:

could be a ring in the cvt preventing it from fully closing and attaining highest gear.
could be rev limited by CDI

if it will get up to 40 on a flat ground but wont go past 40 going downhill it sounds like the second.

Thanks for the response. So what is a CDI and how does it limit the revs? Can I remove it?

Also, I do not know what the transmission is. Its probably automatic or I've been really fucking it up. But I don't know if its 1 or 2 speed. I don't really ever notice it switching gears but idk..

[6rant]

May 5, 2015 16:11:21 GMT -5 moofus02 said:

The computer retards ignition timing to kill power to limit speed. Aftermarket unlimited rpm ignition is still limited only adds 250 rpm. Keeps the motor togather. Check with scootertuning.ca for a gear up kit. They make enough power to run true mid to high 40's with the right gear

Sent from my SPH-L720 using proboards

I'm not looking to change much about the engine. Trying to keep this as stock as possible so as not to fuck anything up. Is it a function that I can remove without damaging anything?

[Elektrey]

May 5, 2015 16:19:23 GMT -5 6rant said:

Thanks for the response. So what is a CDI and how does it limit the revs? Can I remove it?

Also, I do not know what the transmission is. Its probably automatic or I've been really fucking it up. But I don't know if its 1 or 2 speed. I don't really ever notice it switching gears but idk..

CDI is what sends the ignition signal to the spark plug
It's an automatic CVT so it shifts incrementally if that makes sense. You won't notice it shifting.

Moofus knows more about the Zuma so according to him there is a computer (serves function as the CDI too) that basically limits your power once you get to a certain RPM. He says there is no way around it currently except to buy an "unlimited" one but it hardly is any different (only 250RPM). He says its their to protect the engine for reliability essentially. He wrote that if you want increased speed to buy a gear-up kit which basically changes the "final" drive ratio for the scooter allowing it to get to a higher MPH at the same RPM thereby going around the RPM limiter.

[moofus02]

Tuning the cvt will wake that bike up. On dad's c3 I have 5 or 6mm of variator not being used. There is room for improvement. 1000 rpm clutch springs will help the launch. A tuning roller kit will help (dad's doesn't start pulling hard until the cvt is maxed out and the rpm start climbing) find a roller weight that gets the rpm up where it is making power without hitting the limiter then buy good rollers or sliders as the tuning kit is just for tuning and wear quick. Clutch springs and rollers will get you moving faster and help acceleration and hill climbing. As far as belt travel I've herd of people breaking belts when they took the ring out of the variator but i think making the slots longer in the torque driver might get you some more travel

Sent from my SPH-L720 using proboards

[scoots]

The stock CDI in the Yamaha Zuma has both a Rev Limiter and a Speed Limiter - new feature for the 2014 and newer scoots that are EFI. This is why you are plateauing at 40MPH downhill.  The four stroke does not have a washer in the exhaust or transmission like earlier models that you may have read about on the internet.

The only way to overcome is to replace the CDI which is a "major" modification.  In addition there are no aftermarket CDI's for the stock set up that I have found - I tried a dynojet piggyback unit and it did not over-ride the limitations.  Also, as someone correctly noted, the rev limit is there to protect the bike - the aftermarket units only allow an increase of +/- 10% to keep your motor from blowing up, not a big change.

I believe the same post recommended a gear up kit - it will add top speed, but it will also significantly reduce your torque and ability to climb hills.  These are better once a bore upgrade has been installed.  Also, they require use of a hydraulic press to install - and they have a straight gear (instead of mesh) so they make a lot more noise when riding.

Yamaha has done a superb job of tuning the stock configuration.  I would suggest leaving as is if you don't want to make major modifications.

For me - I didn't mind modifying the scooter given the $2500 MSRP - been a fun project.  I now use a Malossi CDI that came as part of a 70cc big bore kit to overcome the speed and rev limitations.  I also found out that once you change the bore, you will have to make other adjustments to match the tuning of your stock bike to see a marked overall improvement in performance.

My scoot is a 2015 Zuma 50FX - my frustration was the lack of acceleration on hills and with passenger on back.  Uphill it would plateau around 20-22, and top speed of 38 which caused a lot of stress in a 40MPH zone.  After massive modifications the scooter has a lot of acceleration even uphill, and can reach a top speed of 43 on motor and 46-7 coasting downhill.  Here is my set-up:

1. Two Brothers Carbon Fiber Racing Exhaust (005-3170107V-B)
a. scootertuning.ca/en/exhaust-systems/100143-exhaust-two-brothers-racing-black-series-bws-zuma-50-carbon.html
2. Malossi MHR Delta Clutch System for Yamaha & Minarelli (M5214739)
a. scooterpartsco.com/malossi/malossi-master-part-list/malossi-mhr-delta-clutch-system-for-yamaha-minarelli?zenid=ert627m2t3bt94pdjbrsp4tit5
3. Malossi Big Bore Kit with CDI for Yamaha Zuma 4T & C3 (M3113864)
a. scooterpartsco.com/malossi/malossi-master-part-list/malossi-70cc-kit-with-cdi-for-yamaha-zuma-4t-c3?zenid=ert627m2t3bt94pdjbrsp4tit5
4. Malossi MHR Variator for Yamaha Zuma, Vino, C3 4 Stroke (M5113603)
a. scooterpartsco.com/malossi/malossi-master-part-list/malossi-mhr-variator-for-yamaha-zuma-vino-c3-4-stroke?zenid=ert627m2t3bt94pdjbrsp4tit5
5. Malossi Belt for Yamaha Zuma 4T, C3, Vino, Minarelli (M6112741)
a. scooterpartsco.com/malossi/malossi-master-part-list/malossi-belt-for-yamaha-zuma-4t-c3-vino-minarelli?zenid=ert627m2t3bt94pdjbrsp4tit5
6. Malossi Torsion Controller for Zuma, Minarelli 50cc
a. scooterpartsco.com/malossi/malossi-master-part-list/malossi-torsion-controller-for-zuma-minarelli-50cc?zenid=ert627m2t3bt94pdjbrsp4tit5
7. Malossi Variator Roller Weights 16x13 Honda, Kymco, Genuine, SYM [658] Grams: 7.0 (M669823)
a. scooterpartsco.com/malossi/malossi-master-part-list/malossi-variator-roller-weights-16x13-honda-kymco-genuine-sym?zenid=ert627m2t3bt94pdjbrsp4tit5
8. Primary gear kit Malossi 13/44 (M6714039)
a. scootertuning.ca/en/gears/9010-primary-gear-kit-malossi-13-44.html
9. Air Filter - Airfilter Tun'r KN Style straight Carbon (28-35mm) (322108) (Placed inside hollowed out stock Yamaha air filter box)
a. scootertuning.ca/en/air-filters/6086-airfilter-tun-r-kn-style-straight-carbon-28-35mm.html
10. Shock Absorber Malossi RS1 310mm
a. scootertuning.ca/en/suspensions/12007-shock-absorber-malossi-rs1-310mm.html

[danko]

Hey scoots, I see you installed a Malossi CDI on your bike, did you have a Force Master? If yes is it a model 0,1,2, or 3? Did you have an issue with the one splice to the TPS wire? The picture in the diagram shows a yellow wire and it says to splice to a yellow, but my 2012 yamaha BWS only has 4 instead of 5 wires and doesn't have a yellow one, just pink, green w/yellow stripe, blue and white. I'm stumped and my bike is all apart and I want it completed.

Thanks -Danko

[bbrins]

I just installed a Force Master 0 on my c3, same engine. The throttle body has two plugs on it. The yellow wire that you are looking for is on the connector that unplugs from the bottom of the throttle body.

[smallfry]

Hey Scoots,

I have installed all the same kit you have. I took it out for its first ride and it did great for the first 10 km but then started to studder a bit. Now it seems to bounce off the rev limiter at 1/4 throttle. Went through all the wiring and double/triple checked everything again but still hits rev limiter at 1/4 throttle. It is hitting the limiter way early. Also set up the throttle position multiple times on the Force Master. Any thoughts?
2017 Zuma 50.(70 now)