Briggs Opposed Twin 16hp - Not runnning smooth

JINMA224XR · Apr 24, 2005

Since I know that each cylinder is firing, does this mean that electrical is not the problem. 

Hey jgbanshee,

Well, it could be on the ignition side, but since you said that the engine ran better when you adjusted the Fuel/air Adjustment, I am guessing that it is a fuel flow problem.

Make sure that your gas cap is venting properly, you might be able to test that by leaving the cap off to see if that makes any difference. There may also be some trash in the bottom of the tank that is restricting the gas flow. But if all these things have been checked, then I am guessing that the carburetor needs cleaning or repairing, but it is only a guess. Have you made sure by looking at the choke, that it is opening fully, the set screw, may have slipped on the wire linkage. It's just a guess, but if the engine was running fine last season and this problem has just risen from over the winter, then most of the time it is a fuel flow problem. When engines sit up over the winter months, often the gas dries up, leaving a gum film, and that causes parts of the carburetor to not slide easily and clogs up the small openings inside the carburetor. It's all just a guess on my part, but most of the time, it is just a simple little part to clean. or a cracked or kinked flexible line somewhere.

However, you did say that the battery was not charging, so for sure you need to have a good battery. If the Battery will not charge, then that means, that one of the cells may be shorting out. I don't know if that would effect the ignition system, but it might. On my motorcycle,, my motor will not run properly, if the battery is not any good. I have even had my Motorcycle engine to quit running while riding it, once the battery stopped charging and one of the cells shorted out. It has an electrical fuel pump though, but maybe on your engine to run properly, the electrical circuit needs to be working properly also.

I always replace the battery on my mower when it goes bad, and I never have tried to operate the mower, with a bad battery. So I just don't know how it will affect things. The charging system is designed to flow into the battery and complete the circuit through the Battery. Just thinking out loud, but if the battery is shorting out, and won't complete the circuit, or intermittently completes the circuit, I just don't know if that will affect the ignition system or not.

Make sure that you see if a good battery makes any difference, before you start taking the carburetor apart for cleaning and or repair.

These things can be really aggravating, I wish that I knew more information to help you. Maybe someone with more knowledge can jump in and save the day.

Good Luck &
Have a nice day,
Joe

jgbanshee · Apr 28, 2005

I just replaced the gas filter today and made sure that the jet in the carb where on mine the no backfire mechanism is screwed in is clean. Still have no luck with the motor. It is still the same. When I listen closely to the motor, I can actually here is miss every so often. I guess I'll try a new battery now and see what happens.

JINMA224XR · Apr 28, 2005

When I listen closely to the motor, I can actually here is miss every so often. 

Hey jgbanshee,

You may save some money at WalMart on your Battery. I bought one this year for mine from one of the battery Specialty stores in my area and they were a tad bit less than Walmarts price.

I would pull the boot off of each spark plug and observe the spark while the engine is running, but BE SURE TO WEAR RUBBER GLOVES TO PREVENT SHOCK. You may be able to tell if the spark might be the problem or not. I would put in new plugs and make sure that they are gapped correctly to illiminate whether one of the spark plugs might be the problem. Check the plug wires and make sure that they have a good connection at both ends and that they are not cracked and no other ignigion wiring is worn and may be grounding out on the chassis.

Observing the spark on each spark plug should tell you a lot about the ignition side.

It would be nice if a small engine technician, would jump in here and offer you more advice than I can.

I'm hoping that it is not a sticking valve or a weak spring.

Don't give up, &
Have a nice day,
Joe

Egon · Apr 29, 2005

Can you check the amperage being delivered to the battery? Can you check each cell on the battery for water and charge? Look at the sparking plugs. This may indicate if only one is missfiring.

Egon

jgbanshee · May 1, 2005

I have now replaced the battery with a new one and I still have the problem. I did however try to cut some grass with it anyway. When cutting I use FULL throttle and it just doesnt feel like full throttle. Everytime I would cut a thick patch of grass, the mower would bog a little and black smoke would puff out. Both cylinders are firing. Still have the screw in the carb about one and a half turns out (lean). That is where it runs the smoothest.

JINMA224XR · May 2, 2005

Everytime I would cut a thick patch of grass, the mower would bog a little and black smoke would puff out. Both cylinders are firing.

Hey jgbanshee,

Ok, if both cylinders are firing good, then we are back to the Fuel/Air side again.

Before you take the carb apart. Take the Air filter out and look at the choke butterfly, to make sure that it is opening all the way. Then leave the air filter out, for just a test to see how the engine is running. Just want to make sure that we don't have an air restriction. If the engine still runs the same, then, IMHO, it is a fuel restriction, either at the carburetor or somewhere before the gas reaches the carburetor.

Did you run some carburetor cleaner in the gas, while you were cutting the grass. Sometimes putting some carburetor cleaner in the gas, can make the difference.

When it comes to taking the carb apart, and checking it out, I won't be much help to you. I would suggest getting a small engine repair manual on carburetors. You will need a can of carburetor cleaner, some compressed air, and you will need to know how to check out the float, to make sure that it is working properly. They do have carburetor overhaul kits, that are available, and I don't think that they cost that much.

Don't give up, you may be getting close to the problem now &
Have a nice day,
Joe

mark1 · May 2, 2005

Hi Again..I just re read all the post and I'm wondering if you ever actually replaced the points. I remember my ole boss after watching me mess with carburator adjustments for what seemed like forever..He said as he walked by "needs new points". and of course he was right.(I hated that).Now days with everything being electronic we forget about the old machines that still have them. (heck you've tried everything else??) good luck /forums/images/graemlins/confused.gif

jgbanshee · May 2, 2005

I dont think that it has points. It has a coil/magnatron ignition system.

Jagmandave · May 3, 2005

If he's getting black smoke, it's unburned fuel, he's not lean. Check the air filter, make sure the throttle is opening all the way and the choke flap isn't closing up on you some way.
First thing tho, you should check the compression, if it's off, you're wasting time with all the other stuff...............

Oop's sorry, just reread that you checked compression and it's good and even

ronnie2005 · May 5, 2005

I have a 16Hp Briggs opposed twin motor on a late 80's Simplicity. I finally got the motor to start and now I cannot get the thing to run smooth.

Sounds like it's been sitting for some time and maybe had gas left in it. If so, drain the fuel that's in it now and refill to about 1/8 tank, then add about 5 ounces of Mineral Sprits. Rock it back and forth to mix it up a little. Start the engine and run just above idle and play with it to keep it from stalling. It will run real bad, but will usually clean the lacquer left behind from the old gas. Run it for about 15-20 min and then drain and refill with clean gas. If that doesn't fix it, pull the carb and rebuild it. Also check the governor linkage and make sure it is not binding.