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Hello all,

I have this 22hp engine that is giving me some intake/carb pop at idle.
I replaced both heads due to a bent push rod on one and valve guide movement on both heads. I have had the carb apart more times than I can count and readjusted the valve lash, trying to nail down the popping. Plugs and fuel pump are new and I tried pulling the coil wire between the two coils to see if that helped.

I have read all sorts of things on the web but figured I would post some video and see if there might be something I missed. Model 406777



Thoughts?

Thanks
Bill

I did not suggest this because it is interfearing with the air : fuel ratio which as we all know will extinguish all life from the planet.
The idle jets need to be a tiny bit bigger .
To verify this ( I can be just a s wrong as the next person ) close the coke just a little
IF the popping stops then too much air & not enough fuel.

Most carbs have adjustments on the idle mixture. On carbs made since about 1995, these adjustments are set at the factory and then capped or covered to comply with EPA regs. The final opening is so tiny that idle settings are always the first to gum up as Ethanol fuel ages. I highly suggest you look for and uncover that adjustment screw. (Sometimes the screw is in plain sight and they make it so no common tool will turn it.)

Some times the adjustment setting is fine, but it simply needs moving back and forth to break the crud free and get back to original cleanliness. Some times the fuel in your area has changed or the engine has aged and a real re-adjustment is required by the engine. You won't know until you find the idle mixture screw.

>> If your engine is over 6 years old, then it is safe to assume that some level of Ethanol damage has already occurred. I highly suggest you treat your main fuel cans with a stabilizer AND cleaner solution, such as StarTron. This will work its way into all your small engines and clean out deposits as you run the engines, thus preventing more trouble while it corrects existing issues.

Hope this helps.

I have had the carb apart several times to clean it and the low speed jets. Guess I need to look a little harder for a mixture screw. I wasn't aware Nikki 2 bbl carbs have one.

Get a bottle of liquid WD 40 ( or similar ) & a spray bottle
Remove the blower housing & start the engine
While manually working the governor arm so the engine is accelerating & decelerating, saturate the manifold .
Lots of white smoke = leaking gasket , warped or cracked manifold.

Hytwr1 said:

I have had the carb apart several times to clean it and the low speed jets. Guess I need to look a little harder for a mixture screw. I wasn't aware Nikki 2 bbl carbs have one.

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• Sometimes the adjustment is directly to the idle Mixture, where the adjustment screw adjusts the amount of fuel.
• Sometimes the fuel-to-air mixture is set by a small jet, and then an adjustment screw adjusts the Volume of mixture. So the idle jet could be clear, and yet the hidden screw still blocked.

There are as many solutions as there are brands of carbs.

Vacuum leak/s alert. Great cause of lean backfires.

Ethanol fuel and some good old water alert.

slomo

Yeah that's what I am thinking and working on narrowing down.

What are the foam "seals" on the choke and throttle shafts supposed to do? Filter dirt or seal the shaft?

The 2 barrel nikki carbs don't have mixture screws. The o ring type seals between the manifold and heads are a very common source of air leaks. There are tiny o rings on the main jets that can leak and cause issues. To clean that carb properly uou really need an ultrasonic cleaner and an o ring kit.


This does not include the manifold o rings

Take off your valve covers again, the watch the rocker arm movement while rotating the flywheel by hand. Look and see that the rocker arms are moving about the same, you could have a bad cam lobe, which was common on this engine back @ 15 or so years back.

Make sure your o-rings are fuel rated.

slomo

Hytwr1 said:

Yeah that's what I am thinking and working on narrowing down.

What are the foam "seals" on the choke and throttle shafts supposed to do? Filter dirt or seal the shaft?

Click to expand...

YEs
They are there to stop dirt dropping into the hole and grinding it ovalThe amount of air the leaks down the sides of the throttle shaft ( choke does not matter ) is taken into account when the jet sizes are determined.

Check your fuel lines and filters for small cracks. My fuel line had a crack that would take in air, but did not leak gas. Check from the tank to the motor...