Topic: It Quit On Me, What Happened??

[JerryRice]

Hello my SOHC Four people,

Everything was going amazing well with my bike - But All Of A Sudden...

I have a 1974 CB350F. Today I fired up the bike and proceeded to warm it up.
Someone was talking to me and I couldent hear them so I shut the bike off
using my ignition swithch (No key just switch).

Then I started it up again. Started great as always.

After about 3 minutes it sputtered and shut down on me.
I tried to restart and it stated for a second then died.
It did that 5 more times. Wont start.

I can get it to start for a few seconds by holding the throttle 1/2 way
but it does not want to stay on! It is acting like it is not getting any
fuel. Fuel is there. It is going through the filter fine.

What happened?

[hopterfixer]

Is there fuel in the carb bowls, and do you have spark?
I will hang up and listen to your answer 

[kghost]

Ya turned the gas on right?

[mattcb350f]

Ya turned the gas on right?

And the choke off since it had warmed up. I'm thinking it could have flooded.

 Matt.

[JerryRice]

Gas is on. Bike not flooded because I can pull the throttle 1/2 way crank. It fires for a few seconds..then quits. So I guess that means I also have spark.

What the heck could it be???

Do points go bad in an instant? Could it be? But it was running great

[hopterfixer]

What do the plugs look like?

[Burke]

Fuel tank vent plugged?

[JerryRice]

Will check plugs after work.

Vent hose is not plugged.

Anyone have any other ideas?

[mkramer1121]

Will check plugs after work.

Vent hose is not plugged.

Anyone have any other ideas?

its not a vent hose...its a vent in the gas cap....could create a vacuum where no fuel is sucked into the carbs.  leave the cap open and try it again.

[mattcb350f]

Sometimes ignition parts just crap out.

Perhaps you could pull the plugs out and check them for fouling, gas, gap bridging etc..

At the same time you can check to see if there is spark.

Is the battery ok? if the lights work then thats enough for spark  

 Matt.

[JerryRice]

I have an aftermarket fiberglass tank with vent hose.
Gas flow down through the fuel filter fine.

I will pull plugs later. Yes light on. Battery strong.
She cranks but dosent turn.

There must be spark. Like i said it will run for a few seconds if I go 1/2 trottle. Then it dies.

[JerryRice]

Any other reasons why it died and wont start?

Does anyone here know anything about points? I dont.
Can points get out of wack easily?

[NGL_BrSH]

Maybe a stuck float.. getting way too much gas.. turn off petcock, drain a tiny bit out of the float bowls then try to start?  If it fires and runs til it's out of gas or when you turn the petcock back on then it's getting too much fuel...


Is it getting air.. suddenly clogged air vent under the seat or plugged air filter all of a sudden?  Pull out air cleaner element and try to start.

Choke malfunction?


pull a plug and set it on the side of the engine and make sure when you're turning it over it consistently fires?

loose killswitch wire, loose ignition/wire, loose fuse under the fuse box?

toasted coil?

bitter suzuki owner stuff a banana in your tail pipe?

[JerryRice]

Ok great I will go through your list tonight and see where we are at.

I guess the POINTS would have nothing to do with it..since nobody mentioned them.
I am totally lost when it comes to points.

[greenjeans]

I'll give a scenario that has happened to me more than once.......
I occasionally forget to turn on the petcock before driving off...I'll get down the road a few miles and she starts sputtering and dies.
Of course now I know what I've done and I pull off to the side of the road and let the bowls fill with fuel.  The first time it happened,
I couldn't get it to start for quite a while until I flipped the choke lever.  (I didn't try it first because the bike was warm)
Don't know why, but it needs just an instant of choke to fire back up...Give that a shot.   Guess it pulls more fuel in there ?

[NGL_BrSH]

well if plugs aren't sparking consistently i'd start working backwards toward the points, condensors, coils etc.

[mattcb350f]

This is strange Jerry 

When a running bike is shut off, then won't start the problem is usually that the engine has flooded from fuel flowing in from the carbs without being burnt. At least in my experience.

The basics for a bike to run are you need compression, spark and a fuel/air mix.

Compression ...should be fine since it was running

Spark..... You're checkin' shortly - points dont have to be perfect to run, just to run well.

Fuel/air....... If there is fuel in the bowls than it should be getting gas.

Let us know what you find

 Matt.

[JerryRice]

I would like to thank everyone who offered help/advise in this situation.
Problem has been located and solved.

The RUN STOP switch was rusted internally and stop making contact.

[mattcb350f]

Thanks for posting the solution 

So the problem started the moment you shut off the bike with the kill 

...makes sense now, but was a head scratcher earlier.

 Matt.

[JerryRice]

Acutally I stoped the bike with my switch (no key).
The Kill must have worsened with vibrations because...as it turned out..
It had a sweet spot of about 1mm in wich the bike would turn over.

I did not know it at the time. Since I bought the hand controls a week earlier..
I figured I should check that first. Sure enouph....

Anyway I rebuilt the switches using an older set. I took the parts form there.

Have you ever disasembled the switches? OMG
They have tiny springs and little ball bearing type balls. What a mess.
But I was able to finally get it all together. Works 100%.

Thanks again to everyone who offered help!