My 1977 honda express, it ran great, it died, now it shoots the air fuel mix out the intake when started. why?

Question

it also goes into very low rpm's when revved. i am not sure what is wrong with it.

Answer 1

Souds like the timing is off

The spark ignites the fuel early

Answer 2

ut oh! take a compression or leak down test

if that's good, remove the exhaust pipe and see is that corrects it

if that's not it check the timing, it could be wayyyyyyyyyy off

Answer 3

To it sounds like the most likely suspects are:

1) Damaged Reed Valve

2) Sheared Flywheel Key

3) Carb is "flooding" from a leaky float valve

your prob sounds most like a Bad Reed valve.

A Simple way to check it :

Remove air filter and  hold a strip of paper over the opening into carb.

Hold Carb wide Open and crank engine.

Carb will try to suck the paper strip in---that's Normal.

If it tries to Blow the Strip AWAY from the opening,,,

That's evidence of Backflow and almost certainly

shows the Reed Valves are bad.

Should be NO backflow.

Your description,,,"...it SHOOTS the air fuel Out..",,,that's good enough for me.

It should not have any backflow strong enough to even be close to such a description.

A "fog" at mouth of carb/intake is not unusual,,,even with a reed valve engine.

Any more than that=Bad Reed

Flooding Carb would steady drip when NOT running,,,

and would Appear to get puked out when 1st started---Sometimes.

Usually they wont even start.

Might be Other things,,,

1st I'd check Reeds,,then make sure flywheel Key is Ok

Good Luck