'77 suzuki gs400 won't start

[Brian Gehrich]

I'm trying to get my '77 Suzuki GS400 back in running condition, and
am having a few problems getting the bike started. The bike sat for a
few weeks while I worked on the brakes of the bike, and when I tried
to start the bike it had developed a dead battery. When I jumped the
bike with a car battery, I was able to get it started, but idled
roughly. The next day I tried to start the bike, but the battery was
dead again. I replaced the battery and tried to start it, but it
would not. After I had given up, the bike fell over (almost all the
way over to the right side) and i picked it up. I gave one last kick,
and it started, ran for about 5 seconds and died. same thing happened
again. i tried to start it again and it backfired, and then backfired
again as i tried one more time. after that i was not able to start
it.

I've tried starting with starting fluid in the cylinder and sometimes
fires and sometimes does nothing. I've got a new battery, replaced
the spark plugs, had the coils checked (as good), and taken the carb
off and blown out all the jets and passages. Any other ideas to try?
Any help would be appreciated. I'm a noobie at being a motorcycle
mechanic (and trying to learn to ride at the same time).

Thanks,
Brian
***@gmail.com

[krusty kritter]

and taken the carb off and blown out all the jets and passages. Any other

ideas to try?

The idle mixture passages and the idle jets and their outlet ports are probably
still plugged up...

If you've tried starting fluid, you probably have the rubber boots off between
the airbox and the carbs and you may have noticed that your carbs probably
don't have choke plates like a car's carburetor...

If there are big round caps on top of the carbs that are held on by two or four
screws, the carbs are what is known as constant vacuum carbs or diaphragm
carbs...

That type of carb doesn't have a real choke like a car, it has a starting
enrichment device which is a tiny carburetor built into the side of each main
carb...

When you operate the "choke" lever, you are actually
opening a small valve in the side of the carburetor that lets air go around the
throttle butterflies and gas is sucked directly out of each float bowl through
a starter jet...

It helps if you turn the master idle knob (it may be underneath the carbs or on
top) which adjusts the idle speed of *both* carbs at the same time all the way
counterclockwise so the throttle butterflies are closed all the way...

This increases engine vacuum at the slow speeds the engine is turning when you
are cranking the engine with the electric starter, and more gas gets sucked
through the starting enrichener...

Don't turn the twist grip at all until the engine fires several times, then you
can hold the throttle open a little bit to keep the engine running until it
warms up, and then re-adjust the master idle knob...

But the starting enricheners still need help from the gasoline coming through
the idle jets. If the idle jets or the idle passages are slightly plugged up,
the engine will be hard to start...

You could also try hand choking the engine by holding your hand over the intake
bell of one carb while you crank the engine with the starter, then if it fires
up on one cylinder, try hand choking the other carb...

I'm a noobie at being a motorcycle mechanic (and trying to learn to ride at

the same time).

Learning to ride with a motorcycle that doesn't run right is very dangerous.
You must get your carburetors working properly so you don't have to worry about
the engine stalling as you go around slow corners, or stalling as you approach
intersections, or stalling as you try to start out from a stop at an
intersection...



# * 0 * #
^

[Kim Neubert]

Post by Brian Gehrich
I'm trying to get my '77 Suzuki GS400 back in running condition, and
am having a few problems getting the bike started. The bike sat for a
few weeks while I worked on the brakes of the bike, and when I tried
to start the bike it had developed a dead battery. When I jumped the
bike with a car battery, I was able to get it started, but idled
roughly. The next day I tried to start the bike, but the battery was
dead again. I replaced the battery and tried to start it, but it
would not. After I had given up, the bike fell over (almost all the
way over to the right side) and i picked it up. I gave one last kick,
and it started, ran for about 5 seconds and died. same thing happened
again. i tried to start it again and it backfired, and then backfired
again as i tried one more time. after that i was not able to start
it.
I've tried starting with starting fluid in the cylinder and sometimes
fires and sometimes does nothing. I've got a new battery, replaced
the spark plugs, had the coils checked (as good), and taken the carb
off and blown out all the jets and passages. Any other ideas to try?
Any help would be appreciated. I'm a noobie at being a motorcycle
mechanic (and trying to learn to ride at the same time).
Thanks,
Brian

When the bike fell over the carbs flooded and that's why it started. That's
an old trick for starting any bike your strong enough to lean over until
fuel runs out the carb overflow. It quit running because something is
plugged up and when the initial fuel was gone it quit.

Noob