Honda NX 125 (XR 125 family) won't start?

Hi,

I have a Honda NX 125 (which I think is of the family of bikes XR 125),
and it won't start. I think it is something to do with the carburettor:
at least, the spark plugs remain dry after attempts to start. Can
anyone help or give me a pointer? A cheap place to find the manual
online would be a help too, if anyone knows of that. Many thanks in
advance,

Luke

 

Turn the fuel on.

 

thanks for that - I'm not a *complete* newbie though

I'm thinking there is some problem with no fuel being sucked into the
piston...anyone have any ideas? (yes, tap is open, to any other
wisecrackers)

luke

 

Sucked into the piston? Sheesh.

OK, check for compression. Lick your thumb, jam it over the spark plug
hole, and kick. That'll tell you if it has compression.

Check for a spark. easy.

Pull the fuel delivery pipe off the fuel tap, turn fuel tap on, and see
if fuel comes out.

If it does, but the spark plug is still dry after repeated kicks, then
the float valve may be sticking. Remove the float bowl chamber at the
bottom of the carb and see if it has fuel in it.

 

Obtain a can of aerosol carburetor cleaner which has xylene, acetone,
toluene, methyl alcohol, etc. in it. Fuel system cleaners that contain
petroleum distillate are no good for this purpose, that stuff
lubricates fuel injectors.

Remove the fuel hose from the petcock and squirt the carb cleaner down
the hose until it fills the carburetor. After about 15 minutes, drain
the float bowl by
opening the float bowl drain screw.

If a lot of rust and brown crud come out of the float bowl, repeat the
cleaning operation.

If there is no drain hose, drain the float bowl into an old rag and
dispose of the rag according to all local fire department regulations.
Do not use the rag to huff the fumes, it will damage your brain, as TOG
and Mark O. know very well ;-)

Hook up the fuel hose and refill the carburetor with clean gasoline.
Hopefully, the gasoline in your tank is clean, no water or rust. It
would help if you put the petcock onto PRI or RES and drained about a
pint of gasoline into a glass jar so you can see how much crud is in
the tank. You might need to remove the tank for thorough cleaning.

If you live somewhere that there is a Wal*Mart or a NAPA auto parts
store, look for Berryman B-12 Choke and Carburetor Cleaner. About $3.00
gets you a 15 ounce can of the liquid B-12.

Mix it 50/50 with gasoline and squirt it down the fuel hose. Leave the
mixture in the carb for about half an hour, and then start the engine.
The alcohol fumes will sting your eyes, so run the engine outdoors.

When a single cylinder engine is hard to start, it helps to turn the
idle speed screw all the way out so the throttle closes fully. After
the engine starts and warms up, reset the screw to the correct idle
RPM.

If you can get the engine to run on B-12/gasoline mixture, add about 2
ounces of B-12 to a full tank of gasoline and go for a ride and let the
B-12 clean your carburetor out.

Don't use a lot of RPM, the alcohol in B-12 or any other carb cleaner
of that type will tend to dry out the cylinder walls, removing the
protective oil film...