Yamaha Chappy upgrades? and a problem

i have a yamaha chappy 50cc, and am interested in 'upgrading' it. what would you recomend i do, firstly to increase the power and speed, and secondly, to reduce the small noises and rattles that they all make??

Also i have a problem with my front light. When i replace the bulb, it blows again in about 10-20secs, i've tried several bulbs (yes there the right watt) and still the same, the battery fluid level is fine, and all of the other lights / indicators work fine..someone mentioned that the wires might be crossed, i've not physically seen any wires touching for the whole of the front light though..any ideas??

another thing, is it idle's fine with the choke on, but when it's off, it cuts out, i've tried messin with the carberetor, but to no avail..anyone know what i can do for this??


RE: Yamaha Chappy upgrades? and a problem

One thing at a time.

1. The headlight operates off the magneto and has nothing to do with the battery. I would check the rectifier to make sure it is properly grounded. When it isn't, instead of bleeding off exess voltage, it dumps it into the electrical system, thus blowing out the headlight.

2.Messing with the carburetor: Do you mean trying to adjust it or actually removing and cleaning it? If you have not removed and cleaned it, make sure the idle passages are clear, as well as the idle jet if it has one. A repair manual for this model would help.

The other thing that would cause it not to run without the choke closed is a vacuum leak. It could be at the carburetor, intake manifold, or cylinder base gasket. The worse case on a two stroke is if the crankshaft seals are bad, then you must disassemble the motor to change them..

Hope this helps!


RE: Yamaha Chappy upgrades? and a problem

thanx, does anyone know where i can get a repair manual ??

RE: Yamaha Chappy upgrades? and a problem



they usually have repair manuals for most mopeds


RE: Yamaha Chappy upgrades? and a problem

messing with the carbaretor, = adjusting it, i havent tried taking it apart and cleaning it yet, i will do though

RE: Yamaha Chappy upgrades? and a problem

is there a fusebox anywhere on it??

as you might have guessed, i'm not the best when it comes to mopeds

RE: Yamaha Chappy upgrades? and a problem

could anyone give me some tips on cleaning the carb pls?? is there any chemical cleaners which would work? or is a coathanger job :)

Carb and other stuff

Mike... these are some general moped tune-up procedures... I figure you only really need the carburetor info.

General Moped Tune-Up Procedures

The first thing to check on a moped that won't run is to see if you have spark at the spark plug..... pull the spark plug out and hold the metal part of the plug firmly against the cylinder head while you kick or pedal the moped rapidly with the key on (if it has one) and the run/off switch (if it has one) switched to run.... it might help to do this at night or in a dark garage to make it easier to see the spark.... it might also help if you have 2 people... 1 to pedal/kick, and 1 to hold the plug firmly against the cyl. head... you are looking for a blue spark to jump the gap on the plug..... make sure you have a good spark plug to start with, a black or gunky or wet one will not spark... If there is no spark.... clean the ignition points like it says below.... If there is spark... squirt a little bit of gas into the spark plug hole and try to start it.....if it starts and runs for 5 seconds and then dies, then clean the carburetor like it says below.


With modern 2-stroke oils you should probably pre-mix between 3 oz.(43 to 1) or 4 oz.(32 to 1) of oil per gallon of gas.....and mopeds are designed to run on the lowest octane of gas you can buy (87 oct.) because they are afraid that somebody who doesn't know better will put the cheap stuff in..... and higher octane will not make it run better or faster or make more power.... Make sure you buy 2-stroke oil.


Clogged or dirty carburetors (on the inside !!) are the most common reason for poor performance... the carburetor must be removed..... then you take off the float bowl (on the bottom).... then you remove the brass "main jet" in the middle of the carb.... hold it up to the light and look thru it.... it must be clean and clear..... if it is not clear you must poke a piece of fine wire thru it.... a wire plucked from a wire brush works good.... or some soft multistrand copper wire like from speaker wire or lampcord wire... don't use a drill bit !!.... next you should screw the idle mixture screw in... !!!! while counting how many turns out it was set at !!!!!..... then remove it and all other screws...... now you must clean out all passages in the carb with aerosol carb cleaner and compressed air (like 100 psi) with a blow nozzle... squirt the cleaner in ALL orifices one by one followed by a blast of compressed air.... while you are blowing air thru the holes feel with your fingers to feel where the air is coming out of and blow the other way too... take your time...... then reassemble all the parts (remember to turn the idle mixture screw out to its original setting... usually between 1 and 2 full turns out from all the way in) and reinstall the carb.


The next most likely cause of bad running are dirty or mis-adjusted ignition points..... to clean them you need some fine grit sand paper (like 400 grit), a piece of clean paper, some scissors, and some aerosol brake cleaner or carb cleaner and some compressed air with a blow nozzle....... remove the ignition cover and look for the points in one of the holes in the flywheel.... lay the bike over on its side and sit on a milk crate or something to get comfortable... then cut some thin strips of sandpaper.... pry the points open with a small screwdriver and stick the piece of sandpaper in between the points and let them close.... then pull the sandpaper out.... do this several times to each side.... now pry the points open and blow them off with compressed air... then spray them with the cleaner.... then cut a strip of the clean paper and pry the points open again and drag the paper thru a few times.... blow them off again with air while open.... now they should be good..... next find the timing mark on the flywheel and see if the points open when the mark on the flywheel passes by the mark on the engine case.... that is the timing and to set it accurately you would need special tools or take it to a shop to have it set.... if it looks like it opens when the marks line up you are probably OK.

use coke to clean stuff

The kids in Kalamazoo have found that Coke also works well as a cleaning agent (coke has some nasty industrial acids in it, that's why I try to avoid them). Just a little tip. But for cleaning a carburator, use carb cleaner (available at most places).

RE: Yamaha Chappy upgrades? and a problem

hi nice to see sombodys got chappys i live on a island in greec and rebuilding one has anybody got a wiring diagram they can email

cheers mike p

Re: Yamaha Chappy upgrades? and a problem

chappyweb /

Re: Yamaha Chappy upgrades? and a problem

thanks for your help with souces of wiring diagram for chappy no luck so far any more ideas

regards mike p

Re: Yamaha Chappy upgrades? and a problem

Ron Brown /


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