Honda 160CC engine on a Try Bilt Mower

[bustednutz]

Hi all, I have a question about this engine. I've never had a honda mower engine before.
I picked up this mower from a friend used. It was always stored and the gas was always drained out of it for storage. It hadn't been started in a couple years.
Well I added some gas and it fired up.
A couple things first:
The engine stumbles a little and sometimes the RPM's go up and down.
It seems to run slightly better with the fuel shut off closed.
(weird, I know)
BTW which way is the off position on the valve dial? Vertical or horizontal?
This engine also has the manual/auto choke system. You slide the choke lever all the way back and pull it to start. As it warms, the choke lever automatically closes.
Once the choke closes, the fun begins witht he stumbling and engine varying the speed up and down.
I mowed a small section of lawn tonight, all went well for 3 passes, then it died.
I started it again, it ran a few seconds, and died.
I added some fuel system cleaner to the gas and it ran a little better without stalling. But still stumbles some.
SO. I'm thinking a tune up is in order.
So....where do I begin? Any thoughts on how to tune this motor, or the choke system, or carb?
The plug looks good as well as the air filter. Perhaps, I'll change those for good measure.
SO.....I need advice on smoothing this thing out and getting it in great running order.

 

[The_Jeff]

I'd start with the carb float. Sounds like it's hanging up and the fuel shutting off is helping it.

When the fuel shut off is parallel to the pipe/hose, fuel should be flowing. If you get confused just put it halfway.

If you tackle the carb you'll figure out how to shut off the gas.

 

[oggb]

Cleaning the carb probably won't hurt it. Getting a carb apart is usually pretty self-explanatory.

 

[DrDusty86]

Spark plug, Air filter, oil change and oh yea... fresh fuel with a swig of techron
Run it...work it hard to burn fuel through it the more fuel burned with a dose of conditioner, the better she should run. Sounds like a sticky float
Dusty

 

[97prizm]

I had a Murray push mower that needed a "tune UP" every season. One thing that will help is to take the bolt out of the bottom of the carburetor bowl. The jets are very sensitive to plugging up with dirt. While you have the bowl off check the float (white plastic disk) it should easily move up and down. All the way up it should make a small click noise, at least in B&S engines. Also install new fuel lines, and install a new inline fuel filter as this will prevent future headaches.

 

[bustednutz]

One more thing to add. When its totally cold, it'll start fine, but the engine RPM's will go up, down, up, down, etc... and then stall out. It always restarts. I find that by manually holding the choke halfway, it helps smooth it out.
So, any other ideas? Keep em coming, you guys are really helping me a lot. Thanks.

 

[TFB1]

The up and down in RPMs is called surging and is indicative of a lean fuel mixture(why choking helps), probably has some gum from old gas in the carb... If it has a fuel mixture adjustment you can try backing it out to enrich the mixture, but I'm betting you'll need to rebuild the carb... If the carb is gummed up, the fuel system cleaner may fix it after a few days...

 

[hemitom]

check to make sure choke is fully open when warm.

 

[DrDusty86]

FLOAT ISSUES clean gas with fuel conditioner... SHE's sticken

 

[bustednutz]

I cleaned the float. It seems to go up and down very smooth. Not sticking and the float bowl is clean. Maybe its a carb gasket causing the surge? Any other ideas?
Maybe I should take the carb out and clean it really good.

 

[DrDusty86]

Trash in the fuel line? Cold it will run rich and pull in more fuel and not as much air.
My next suggestion would be to take the fuel tank off and follow the fuel line into the carb... look for a mesh screen...its probably right where the line goes into the tank.. clean it or replace.

 

[TFB1]

If it has good fuel flow from the tank to carb, your problem is INSIDE the carb... There's likely a spec of gum, rust, dirt, or whatever lodged in one of the passages, likely will need blowing out with compressed air...

It will only be running rich when cold IF the choke is closed, otherwise the carb is stupid, it doesn't know hot from cold...