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 Please Help! Zuma getting too much fuel. 
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Joined: Wed Oct 18, 2017 5:37 am
Posts: 5
Post Please Help! Zuma getting too much fuel.
Hi All, i've been lurking around here for a bit, reading and trying to learn what to do to zip up my 125, i've run into a little problem and i thought i'd see what ya'll have to say.
First, i bought my kit from Trish at Zumasrus, and the fuel parts from Chris with RC Scooters.. i cant say enough about either of them, both have been super helpful, and have tons of good information to share.
i have some sort of wierdness going on here, and i'd like to see if someone has any other ideas.

I have a 2012 Zuma 125, I went to ZumasRus and they put together a "kit" for me so i have the NCY 158cc BBK, NCY Cam, NCY exhaust and NCY super transmission kit.
I wanted to try and avoid using a piggyback fuel controller, just to have one less thing that can go wrong. some of the kits (like tiada) have a bbk with an additional injector and no fuel controller, i wanted to do that. zumas r us doesnt sell injectors, but said since the zuma 125 is a closed loop system, the zuma will try and compensate and should work without a fuel controller. they said they had a guy in their shop who was running his personal bike like that with success.
so, thats what i did,i put it together that way, kept an eye on the exhaust and watched so as to try and not lean it out and burn it up.

well it runs, and its ok on the bottom end, mid throttle i have a lean pop that i dont like, it stalls sometimes, and has a little dead spot just off throttle.
i talked with Chris Cey about an injector and he said he knew exactly the injector i need.
when i got it in, the scoot was super fat.. to the point it wouldnt idle on its own.. i did the ecu reset several times, and on one of these i was able to get it to idle for a while, i put it together (while it was idling) and took it for a ride.

before i get into how it ran riding it i want to say, the idle still worked until i turned the bike off and started it back up.. after that idle was gone.
(ive been able to get it to do that twice, it will idle as long as you keep it running, but as soon as you turn it off, that ability to idle is gone). if you disconnect the idle air valve it will have a check engine light, but will idle, that tells me the idle air valve fails open.. (too much gas)
so, riding with the new injector.. if you pull the throttle wide open it sputters and pops (very rich) until it finally finds it's place and starts to pull, it pulls ok, but not super hard (again rich). its mile an hour is much better than with the original injector this thing will run almost 70 now when before about 55 was all i could get. so it was running out of gas on the top end. in my experience motors melt down when they do that, but ok.
if you take off at mid throttle, the bike leaves much harder (again too much fuel). mid throttle lean pop and stutter is gone. (as expected it's getting more fuel)

at a stop sign, you have to hold the throttle to keep it from dying.

spoke (email) with Chris and he said these injectors are coated with some kind of protective chemical that makes them all gummy and they need to be cleaned. so i followed his recommendation and soaked it in gas for a while, i also hooked it up and put carb cleaner(dont squirt that stuff in your eyes) under pressure on the inlet and pulsed 12v to it and let it spray, the first couple of pulses it was kind of a nasty squirty pattern, but it cleaned right up and now sprays a perfect fan (as it should) put it back on the bike, reset the ecu and still have the same problems.

other things ive done.. i have put the stock injector back on (just to make sure i haven't screwed something else up and am chasing a ghost) with the stock injector, it starts at first bump and idles just fine. though it didnt seem to need it, i have changed the plug too.

so.... from where i sit.. i can spend a couple a hundred on a fuel controller that only adds fuel, so that means i cant use this shiny new injector, i just use the stock one..
will the stock one be able to push enough fuel to make the top end work with a controller?
My assumption is that many of you are using these injectors, what are the chances of something being wrong with this one? when i had it under pressure, it wasnt bleeding, it seems to work fine.
i hate to spend 2 or 300 on a fuel controller after buying a 100 dollar injector that i cant use with it.

Thanks for your help!

Fri Nov 03, 2017 5:58 am
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Joined: Mon Jun 30, 2014 1:36 pm
Posts: 271
Post Re: Please Help! Zuma getting too much fuel.
An injector with no means to control it has the responsibility to cover the wide range of its fuel spectrum needs from each 1k to 9k + rpm range. so yes. you are right in the assumption that a " larger" injector that is setup to not blow up your piston is going to experience rich spots. that is why I always recommend to anyone to just jump in and get the Hoedar ecu system. It will correct anything you have going on wrong. Its a smart chip system. It corrects any missing gaps and has fail safe backup. So as " oh crap" of a moment it is to hear that you should get it... you will not regret one penny invested in it. Cuz should you chose to ever do any form of modification past the 155bbk setup... you have the most important part to control your whole setup. that hoedar allows for any setup you desire, minus turbo charging... there is a whole other model setup for that system. So minus the function of a 218cc with a turbo which would put you up above 100mph on that dinky bike anyway and I dont know anyone who would enjoy that speed on such a small bike. but to each his own. So yes. i would say get the ecu system. An injector alone is going to cost about 1/5 th the cost of the system but you will still have the same type of problems. vs ... absolute efficient bench marks for each rpm range of the bike. The old way, if you didn't know was through a piggy back system, aka, juice box pro... ect... and that was a pain in the royal butt to try to make perform properly. I would say you could plug in the new ecu, get chris to hook you up and get your general info plugged in so the piston is submerged in a healthy invironment... then ride ... come back... read the data, make tweeks, ride, data, change maybe 2 or three more times max... and your bike will run like it was naturally a 155, 164, 180, 190, 205, 218, 236... it makes any cc size feel like it was right off the factory line.... no problems... so its worth it. Bike is faster cuz it always at optimal fuel air mix. Your other choices are as you know... to find a better fitting injector. ( if there is one ) if not you are correct... you will need the Hoedar... I am not sure if it will require you to purchase another injector along side that system. I would assume if you are running rich on top end you will be fine.


Fri Nov 03, 2017 8:10 am
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Joined: Wed Oct 18, 2017 5:37 am
Posts: 5
Post Re: Please Help! Zuma getting too much fuel.
i have some experience with the bosch motronic and other powersports systems, tons of experience with the dynojet stuff, i've done a couple of megasquirt builds. i've played with the dobeck and tbr stuff mostly with bigger engines (polaris), so i'm real comfortable with all of that, my goal was to keep it super simple.. this a little toy scooter that i bought to put on the back of the motorhome.. (but i cant leave anything alone).
since i dont know of any way to turn this injector "Down" without throwing electronics at it, i just ordered a dobeck, which is what i probably should have done in the first place, and put my stock injector back in.
i doubt i will go any bigger in this bike, if it will do the things i've asked of it (which i've seen that its capable of) i'll be happy (well maybe)
the reason i went around to the various vendors and told them what i wanted to do, and asked what they recommend is because i didnt want to have to do all of the research and learn all of the nuances of the zuma, my plan was to pay for someone else's r&d and just have a fun little toy.. dont get me wrong l live for this stuff, i like learning new stuff, just got a lot on my plate.. :). so is this hoedar and offshoot of microsquirt? or something else?

Fri Nov 03, 2017 10:49 am
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Joined: Tue Jul 06, 2010 11:06 pm
Posts: 2496
Location: Taiwan & Hawaii
Post Re: Please Help! Zuma getting too much fuel.
hoedar ecu is pre programmed and setup for the zuma 125 so it's plug/play. all the settings are there to start a 125cc zuma engine and run properly. for larger sized motors we just mess with the cold start and fueling. timing i only touch on more higher end builds like 218cc.

as for the injector it was setup for my 155R bbk that comes with a matching camshaft. works great and never had any issues with cold start or running rich. at the same time not all aftermarket engine parts are designed the same. so got me thinking that camshaft must be on the smaller side, basically a sport cam that's just little bigger then stock. this would cause it to run really rich.

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viewtopic.php?f=54&t=16410 <------ RC R&D

Thu Jan 04, 2018 3:58 am
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