Cannot start bike

Hi,

I have a simple Suzuki (grey import) EN125. I expected it to be tough
to start the bike after the cold and damp weather. The bike had been
under a light-weight rain cover for say 6 to 8 weeks. I have a small
"slope" near the house which is steep enough to get up to, say, 10
mph. I have tried to bump start the bike on this slope and it almost
fires then dies or does not fire at all. I have tried bump starting
with full choke, half choke, no choke. I have tried to jump start off
my car battery (car not running I have been advised). The bike starter
motor turns (not burned out yet) but the bike does not attempt to
fire. Anything else I can try to get this bike moving?

Regards

Clive

 

I used to have a GN125 that did this after beft for a - a thump on the
carb would

 

I used to have a gn125 that did this after being left for a while - a
thump on the carb would sort it out though so I am guessing something
with the carb like a stuck float.

Pull one of the plug caps and check that the plug is firing with a
good strong blue spark, if not then start looking at the ignition
system.

I would pull the spark plug and see after you have tried starting it
whether the plug is wet with fuel or not - if it is then heat it good
and hot with a blowlamp and then try restarting it without choke - if
the plug is dry then fuel isnt getting to it so check fuel is getting
to the carb, then check the carb itself.

Hope this helps

 

Check the sidestand ignition cutout first of all.

 

Fueltap, plugs, tip switch, sidestand switch, clutch switch are all possibles
on this one. Sounds more ignition related if it is turning but not firing.

Fraser

 

Does it have a kill switch?

 

Had that with a YPVS Yam 350 years ago, because the 2-stroke twin vibrates
with a sort rocking motion, the switch "made" when one cylinder fired and
was sometimes intermittent when the other cylinder fired (or not as the case
may be).

A short wire link was hastily crimped with tags to suit the connector and
plugged in instead of the switch.

 

Hi,

I'm limited in my knowledge and equipment to test things however I
tried the following today.

Bump start in second. The bike sort of "rumbled" but didn't get to
fire

The battery voltage reads about 11.8V (given possible inaccuracies of
voltmete).

I unscrewed the spark plug from the cylinder and the end is black. The
gap didn't seem "wet".

I cranked the engine with the spark plug out and could smell petrol so
I guess fuel is getting from the tank through the carburetor and into
the cylinder.

When I was cranking the engine I couldn't see a spark across the plug
gap when the plug was in the spark lead (?) but out of the cylinder. I
have read something about when trying this having the spark plugs "in
contact with metal" but I would have thought the capacitor/inductor
thing that creates the HT required the gap to create the spark and any
short-circuit would, well, short-circuit the spark.

I can't take out the HT/spark lead (?) to test its resistance since
one end is tucked well under the fuel tank and I don't have the tools
to remove the tank.

The local bike repair guy is of course closed today.

Clive

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, Clive

That's too low. Charge it. Unless it's a sealed battery make sure the
fluid level is between the lines in each cell. If not, top it up with
distilled water. Do *not* use tap water.

If the end is black, try a new plug. Or clean this one.

The metal body of the spark plug *must* be in contact with the earth on
the bike for this to work. Touching it to the cylinder head should be
enough. Be careful how you hold it in place, it will give you quite an
unpleasant shock if you touch it. Use the cap to hold it.

You should see a nice fat blue spark.

 

That's fucked and may well be the cause of the problem. A decent
fighting fit 12v battery should show 12.5v plus.

 

Got it working !!!

1. Took out spark plug, cleaned surface with some 400 emery paper and
tested spark by holding body of plug against cylinder head, a yellowy
spark was seen when I turned over the bike. Not great but probably
enough. Refitted spark plug and lead.

2. Closed fuel tap from tank.

3. Put small container under carburetor drain screw and undid screw.
Yellow liquid with a few black particles drained out. Whether the
black was from within the carb or muck around the screw I don't know

4. Opened the fuel tap for a second to "flush" the carb. Refitted carb
drain screw

5. Opened choke fully, no throttle, turned over the engine and it
fired up after 2 seconds

Moral ? Probably close the fuel supply tap and drain the carb if the
bike is to be left over winter.

Thanks to all for suggestions.

Now ... the rear drum brake is sticking when I depress the foot pedal.
I can "knock" the "swing arm" that engages the drum to release the
brake. I will degrease and relubricate all external rods and linkages.
Maybe a "release spring" inside the drum has failed or is "gummed up".
That's a job for the mechanic.


Clive

 

Well done.

"Shit in the carbs" is stock ukrm answer #2 (in a series of, err, about
4!).

I can't believe no-one posted it.

 

In some warmer climates petrol is formulated diffferently for winter
and summer.

If your petrol was very old, the volatile alcohols which make it
easier to start an engine during the winter may have evaporated away,
leaving gum and varnish deposits in the jets and various ports and
passages of the carbuettor.

The petrol in the fuel tank would be fresher than the petrol distilled
in the float bowl and that would help to clean the carburettor
slightly.

But you should make a habit of adding a few ounces of clear
carburettor cleaner to the petrol tank before trying to start the
engine after a lay off or winter storage.

This carburettor cleaner should contain clear solvents like toluene,
acetone, methyl ethyl ketone, it shouldn't be a carburettor dipping
solvent. Carburettor cleaners that are mostly naphtha (petroleum
distillate) are almost useless, you want the cleaner with the strong
solvents.

5. Opened choke fully, no throttle, turned over the engine and it

That's the correct starting procedure in cold weather. Full "choke",
no throttle at all.

Your carburettor doesn't have a real "choke", there is no flat plate
to restrict airflow and enhance vacuum to suck petrol out of the float
bowl.

There is a small air valve built into the side of the carburettor. It
is part of the cold starting enrichener system. When you apply the
"choke", the air valve allows air to bypass the throttle butterfly.

This airflow sucks petrol directly out of the float bowl through a
brass tube which can become plugged up with gum and varnish from
evaporation of the fuel in the float bowl.

One more thing:

When you attempt to start a carburettor-equipped motorcycle engine
after winter storage, turn the idle SPEED knob or screw all the way
counterclockwise first.

This closes the throttle butterfly completely, increasing engine
vacuum and making it easier to suck petrol out of the float bowl.

Then apply full "choke" and do not twist the throttle grip. When the
engine fires up, keep it running by twisting the grip slightly.

When the engine is warmed up, turn the idle SPEED screw clockwise so
the engine will run at the specified RPM.

 

There is no so-called "release spring" inside the brake drum. There
are two brake shoe *retractor* springs, though. They hold the brake
shoes away from the roatating drum and against the operating cam which
is rotated by the short lever that you can see moving when you stand
beside the motorbike and push the brake pedal with your hand.

One of the retractor springs may be broken, and it's likely that there
is an accumulation of brake dust inside the drum. This should be
removed every time you replace brake shoes.

The brake dust may have accumulated on the operating cam shaft, which
needs to be cleaned and re-greased every time you replace brake shoes,
or if you have been riding through standing water frequently.

If you want to ride a motorcycle on a regular basis without a lot of
frustration, you really should learn how to do simple maintenance
tasks, such as changing a tyre, replacing brake shoes, making various
adjustments to the controls and keeping the fuel system clean.

 

<snip utter irrelevancy>

Clive, ignore this post and concentrate onfreeing the seizing brake like
I said.

 

That means the steel pivot pin has seized in the alloy drum plate. Very
common.

Remove back wheel, remove drum plate, knock out steel pivot pin, clean
up, lightly grease, reassemble. Easy.

 

Yes, there are.

They are therefore release springs.

Absolute *nonsense*

<snip more crap>

Clive, if you're reading this, the seizure is a very common thing, and
it's generally caused by an interaction between the steel of the pivot
pin and the alloy of the brake plate. Just do what I said and ignore
this nonsense.

 

Using emery paper on a spark plug is not a great idea, it isn't easy to
remove every last trace of grit and it doesn't do the rings any good.

Using a wire brush isn't much better, it can leave traces of metal deposits
on the insulator nose.

A new plug is the favourite option - or if you're desperate, burn the soot
off the plug with a blowlamp.

 

Look out! A full blown Four-eyed Juicy Fruit tantrum has begun!

 

In southern California, where it doesn't snow and the highway
maintenance crews don't salt the roads, drum type rear brakes still
stick like Clive described and it has nothing to do with corrosion.

Brake dust and road dirt mix with the grease on the brake cam shaft
and it sticks.

Also, the brake cam itself will begin sticking when the brake shoes
are almost worn out.

When replacing rear brake shoes, one must always lubricate the brake
cam and the brake cam's shaft.

There are also problems with brake linkage geometry that lead to rear
brake shoe binding, especially if there is a solid steel rod in the
linkage instead of a cable.

Now, get back to your fruit juice, Four Eyes...