Not sure on model of mower it is a talon 4 stroke when you work the throttle on the handle bar the carby is open it won't close or open it just stays open would it have anything to do with the spring as it only has one on it. Thank you Vince.

Check that the contact in the carburettor is open circuit when you're trying to start it. The way the ignition is killed on pull start lawn mowers is by the throttle linkage creating a dead short to the coil (grounding the circuit to the body of the mower). Also check that the spark plug lead isn't damaged, the spark plug is in serviceable condition, the coil wiring is undamaged and connected and the coil pick up itself is mounted firmly. A similar question was posted approx 5 years ago with no response - this could possibly be a manufacturing fault with this brand of equipment.

check that the cable clip on the carby for the throttle has not allowed the outer cable case to move
readjust at the clip for idle speed so that the butterfly lever hits on the idle screw when the throttle is in the idle position

Throttle cable stuck ,or carby ,spray cable with WD40 and work the leaver back and forth,check carby to make sure a return spring hasn't come off,is the motor a Brigs and Stratton. Make sure the leaver at carby it moving whilst you are working the cable leaver,good luck.

if the bolt pattern is the same and the throttle cable is the same , any carby will fit
the problem is most likely dirt or water in the main jet of the carby or insufficient fuel flow to the carby

Sounds like a burned or bent valve. If the mower has a lot of use time on it, you might consider having the head re-worked, as valve spings get worn, they get looser and it's very possible that they're opening and closing excessively and could even strike the piston and bend the valve shaft if it's opening out of correct timing. If they open more than they should (the stroke is longer than design permits) then it won't close completley at the right time, and the blow-back will burn the edges of the valves and make leakage even worse. The resulting loss of pressure will cause bad compression (loss of power) and a valve which is open when it should be closed will cause a backfire, which is simply the explosion inside the compression chamber escaping back through an open valve. As for the high idle, if the throttle is cable operated, a rusty cable or bent cable inside the sheath may cause the throttle to stay in the same place rather than return to a completely closed position. The same may be true of a dirty carburetor intake valve. The mower may have multiple problems, but without knowing exactly the usage history and work time on the motor, it's just an educated guess.

Check the attached links,
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YAMAHA MANUAL STORE
Motorcycle Owners Manuals MyBikeManuals com
Electrical Testing Shortcuts with Vince Fischelli Part One Battery Testing
Steps to Take When Your Motorcycle Won Start Dennis Kirk Powersports Blog

not if is a 4 stroke engine not being bothered to include engine make , model year etc makes answering accurately.
you could even say the color of the smoke
so here is a generic answer ( 4 stroke )
it indicates that there is a problem in the needle and seat and there is no fuel flow control in the carby
if it is a 2 stroke with a carby --same problem
ordinary engine oil (20w-40) for 4 stroke sump) and special 2 stroke for 2 stroke engine

Turn both jet needles CW to stops (lightly), then back out each CCW 1-1/2 turns. This is a basic setting that should allow the engine to start and run. Start the engine and allow to warm up, then pull throttle full on. Adjust H needle CW until the engine starts to speed up, but continues to 4-stroke. Proper setting is when the engine 4-strokes unloaded, but immediately 2-strokes when cutting. Release the throttle and adjust L needle CW for better idle, yet allows the engine to 'follow the throttle'. Adjust idle speed screw so that the chain stops turning, but the engine continues to run. Hope this helps!

no spring in the grip!
id suspect the cables are binding up inside so disconnect at the carby end then & see if they are moving freely
Cheers Rob

The internal govner is a good option.