Rebuilt carb but won't start, it tries to but coughs back through carb, is my engine out of timing? can you help? thanks otis

There are certain things you need for it to start and run,
A good spark, and at the correct time.
A fresh fuel supply to the cylinder
A sealed engine with no leaks
So with the plug well grounded against the cylinder do you have a spark when you crank the engine? if you remove the flywheel is the key not sheared?
After cranking the engine do we have signs of fuel on the plug tip? do we have excessive fuel in the engine ( carb needle leaking ) when the engine was rebuilt were the crank seals in good condition? was the cylinder sealed properly onto the crankcase?
Do you have a pressure tester to see if the carb is leaking at the needle?
Was the piston and ring in good condition with no excessive ring wear?

When was the last time you ran it Prior to this problem? When you rebuilt the Carb, did you pull out the plastic plug on the top of the carb? Many B&S carbs has a air plug up top that clogs. When gummed up, it causes surging. Did you clean all the tiny holes in the Jet and Emulsifier?

Try to pressure test the carb to see if you have an internal leak. If it won't hold pressure then it is junk and needs to be replaced. If it holds then double check that you didn't accidently put the gaskets and diaphragm in wrong. If it holds and still doesn't work right replace the carb anyway. They are relatively inexpensive

If you need further help, I’m available over the phone at https://www.6ya.com/expert/kelly_69a0cf1b13789df1

Had a similar problem, I rebuilt the carb and fixed any gaps/cracks in the intake boots and carb-engine gasket. runs ok now

Mine was stored for 20 years, I ended up replacing the seat and needles, cleaning them thoroughly and when I tried starting it, nothing!! No gas was going to the carbs, it turned out to be my gas pump, it was seized by the old gas remains 'varnish' so I had to clean it numerous times, soaked it in gas cleaner (short period at a time 15 minutes or so, being a very powerful cleaner, you cannot leave it for long without causing greater problems, thus I was able to get the pump going by boosting it with my car batterie, having more cranking amps directly to the pump, the pump was able to release itself from the old crusty varnish.

carbs need to be pulled and cleaned, they might even need to be rebuilt

Usually spitting and coughing back out of the carb is due to a lean fuel air mixture. I'd go up one size on the slow speed jet in the carb. Maybe raise the needle by putting a 0.020" (standard 3mm flat washer) under the needle in the slide. Remove the needle from the slide, put the washer on from the long end of the needle, and replace it.

The leak is another matter. Usually when the stock CV carb leaks, it's because the accellerator pump diaphragm has a hole in it. This allows gasoline to get on the top side of the diaphragm and then it comes up through the top of the hole that the pump push rod goes down through.

All in all, it sounds like it is time to have your carb rebuilt. A thorough cleaning INSIDE and out and a few parts replaced. That should cure your problems.

Good Luck
Steve

I'm not too familiar with Triumphs but assuming your bike has carbs and not fuel injection, then it is time to clean the fuel system. Remove the water trap bowl at the bottom of the petcock, (gas valve). Is there any water or trash in the bowl? Drain a cup of gas from the tank. Is there any water or trash in the cup? Dump it, clean it and re-mount it, ( not all bikes have a water trap bowl ). Install an in-line fuel filter.

For each carb > Drain the carburetor. There should be a screw on the lower side of the carb float bowl. Remove the screw then replace it after the fuel drains. Turn the gas back on and wait a minute for the carb to fill with gas. Install a new stock NGK spark plugs and start the engine. If the bike doesn't start and run properly then shut off the gas and remove the carburetor from the engine.

Remove the float bowl and clean the entire carb with a spray carb cleaner from the auto parts store. Wear protective goggles to avoid getting spray in your eyes. Spray into all the little airways and fittings in the carb. Remove the idle screw and the air screw on the outside throat of the carb and spray into the screw holes as well.
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Be sure to put these two screws back in the same hole they came out of. IMPORTANT > do not tighten these two screws down. Only screw these in until they LIGHTLY seat. Now turn each screw one and one half turns outward. Put the rest of the carb back together, clean the air filter and install the carb. Let the float bowl fill then start the engine. This process should get you back on the road.

You may want to go to a richer main jet. If the jet is (for example) a 178 then change to a 180 or 182. This should fix the top end problem. Do this only if cleaning the carbs doesn't work.

Please rate this solution. Thanks!

check your firing order as well as your timing