Carburetor or the Standard Union or for
Carb. is a very simple carb to work with, there is idle screw and on
some models there is a way to adjust the metering pin to tune the high
range for max out put. but on these carbs there is only one adjustment
that is the idle.
the one thing is there is a float
in the bottom
of the carb and if you dont get the carb level as I see in so many
any miss alignment of the carb
will result in a loss of power .
float in the carb acts as a on off fluid flow to the float bole on the
bottom of the carb if the gas level is not at the right hight in the
float boles it will starve your engine this will rob you of horse power
and you wont have full power.
So when you start putting the engine in place in your frame
make sure that the carb is level with the bike when on the ground and
you will have max power to the engine.
The carbs do not have a good float shut off pin in side it if
you leave the shut off valve off as I read you run the risk of blowing
your engine up by filling the cylinder with gas then when you try to
start it it will hydraulic the head and you will brake a stud or two as
we did or if your lucky it will drip all the time not a good thing .
If you see gas under the bike STOP THERE and take plug out and
turnover engine a couple cycles to get the liquid gas out if the
cylinder head this will save the expense and down time we had to wait 2
weeks to get $15.00 parts that were not easy to find there is 3
different studs to my surprise and only one set will work, the the 50cc
takes a 6mm at 3-3/4 in. Long and a 4-1/4 in. stud the 80cc is a 8mm
4-1/2 in. Long so it was a little learning experience.
Our 50cc jet motor had 6mm - 4-1/4 in. long studs
The gas in the tank when full is putting a pressure if about 4
lbs. On the carb ( 8 lbs. Per Gal.) so do not omit the shut off valve!!
There is a carb you can get that has the meatier pin with
adjustments on the pin to tune the high speed tuning
As you can see the cable is attached to the slide and metering
You do not want to adjust cable to tight on top of the carb
this will razes the slide and you will have problems starting to much
fuel and could fowl plug with too much fuel .
Adjusting the the float in the carburetor ;
Both of the 49cc and the 80cc carburetor use a donut stile float with a
adjustable brass retainer to hold the fuel inlet valve in place
You need to look at this when you feel
the power dropping too much , 4 cycling, smoking .
Remove the carburetor to do this, undo top pull slide out, carb. main
body in hand.
Remove bottom and pull out
donut float there is a pin holding the brass peace in place it holds
the fuel inlet pin in place.
The brass get bent so the pressure is not pushing on the inlet pin
valve , straighten this part flat level gently , then insert gas inlet
pin and place the brass peace and pin it and see if the brass is only
on the shoulders of the gas inlet valve .
Place the donut float on the brass and see if the brass is only
touching the shoulders of the gas inlet valve now this all happens with
the carburetor up side down use a flash light to see the parts it is
working now .
Leave the float level alone I do not have the level width measurements
is a book that will give you some insight on what they are all about.