Wheelie needed b4 kickstarting; stalling enging at +15mph;

[kwosha]

Just bought my 1983 Aero50 scooter a few weeks ago and here are the problems I'm having (I know this is a spree site but since the Aero 50- with the NB50 engin-is referenced here, I'm hoping it's ok to post this)

1. If cold, the engine won't kick-start unless i pop a wheelie with it for about 10 sec. then put it down and try again- works every time., then idles a bit like it's going to stall, until it warms up, then it idles fine. Basically that means it's getting the gas flow going right? If warm, the engine re-kick-starts easily.
2. It runs, but after it gets to about 12-15mph, and i try to accelerate more, most times the engine wants to stall unless I let up on the throttle; SOMETIMES, usually if riding down hill, the engine will sort of "get over this wanting-to-stall hump" and go on to accelerate to top speed but this is unpredicatble
3. I took apart the carburator hoping to de-gunk it, but it was very clean...almost brand-new looking so that's probably not the problem
4. I changed the spark plug but this didn't help
5. I adjusted the air and fuel mix screws on the outside of the carburator but this didn't seem to fix the problem.

I'm looking for what to do next. Any Ideas? Maybe a faulty auto bystarter? Faulty diaphragm/ fuel valve?

I would greatly appreciate any advice.
Thanks
Kevin

[vette76]

if u dont have an air box u need it. i would clean the carb even tho it "looks" clean, there are a lot of places that can be clogged.

[noiseguy]

We are now talking about Honda 50 anything, scooter related.

The wheelie thing has to do with your fuel setup. I'll bet you don't have to do a wheelie if you go to restart it after it's been running, do you? Drained carb is the culprit here.

As for the 15 MPH boggie, check your main jet and needle valve setup to see if it's stock, and check your aircleaner and air duct.

[kwosha]

1. but why would the carb continue to drain after i got it going? that would suggest a leak in it right? like if it sits over night the carb must be draining or leaking b/c every day i start it, i have to pop the wheelie?

2. are you are suggesting i guess that the main jet and needle valve setup might be the wrong make/model?

thanks..and sorry for the confusion...i'm definitely new to this
KO

[ferchja]

The wheelie thing is not the fault of the carb bowl, but the idle circuit. You are basically getting fuel in the intake by emptying the bowl through the main jet, then it will start. The reason it starts again after warm without the wheelie is that you do not need the extra fuel when it is warm. I would look at the bowl idle circuit and bystarter as the problem there.

The top speed bog is likely fuel delivery issue with the main jet and or fuel to the bowl. The float needle and seat may be clogged causing the fuel to starve, and/or the main jet is clogged and not getting the fuel. Or like suggested the wrong jet (i.e. too rich and or bystarter burping fuel into the intake when it should be closed). At full throttle the main needle in the main jet has nothing to do with mixutre, it is for midrange when you are not at full throttle. Idle (0% throttle) is through the idle air/fuel screw and the throttle screw (air screw)

[kwosha]

As i've been trying to narrow down the problems this afternoon i've found something peculiar.

If i put the scoot up on the stand so the back wheel is off the ground and let it idle, the wheel barely, if at all, will spin...basically it's idling. However, if i even TOUCH the throttle a tiny bit, and then let go, the engine continues to rev up and accelerate the wheel until it's bascilly going full speed with the engine reved way up. It doesn't go back down on it's own , only when I pull the rear break. Then, most times it will stay idling on it's own, sometimes it will tend to rev way up again witout touching the throttle at all. This seems very abnormal to me. Would this add or refute evidence to a faulty bowl idle circuit and/ or bystarter?

To troubleshoot, should I first just take apart the carburator again and try to clean out the float needle and seat with a small wire of some kind (should't be hard to find the right size, I'm an orthodontist) and then if that doesn't work, purchase a new bystarter off of bikebandit.com OEM or some other site?

Basically, I understand that I should clean out the main jet to try and get a better higher speed performance, but I'm still a little unclear how exactly the "Idle Circuit" works. I don't know what to do to specificially diagnose the bowl idle circuit and bystarter.

Thanks again

[MySpree]

your idle speed is up to hight first thing and the lack of speeed, are u at a lack of power to, ifso you might wanna think about getting up muffler torched.

[ferchja]

You have a vacuum leak on the bystarter, and the idle circuit at the base of the bystarter is clogged. The symptoms are exactly typical of what you describe. If under load it doesn't perform you have a clogged main jet.

1) Test the bystarter like I have described previously.

2) If that creates a fast acting throttle (i.e. on the stand it drops when you let go and goes up when you crack on it) Then you know you need to replace the oring on the bystarter. Your lack of power on full throttle is either no air filter, if that is there it is either compression or main jet clogged there are no other things to adjust at full throttle then that. To head off anyother suggestions, it is not the reed valve.

I beg to differ with Myspree, exhaust is not an issue with that bad of performance if you can get it to full power on the center stand, the muffler is fine to get it running. Later you may have to camp fire it to get another 1-3 mph but at the very least you should get 25mph with everything else in check.

If you were in the SE WI area I would help you out. The carb on these things are so simple compared to motorcycles and cars. You could mail it to me and I would set it for you and send it back. I could turn it around in one night (If i have the oring with it).