Engine stumbles with poping exhaust on a kaw 19hp engine

vintageman

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  • / Engine stumbles with poping exhaust on a kaw 19hp engine
I have a scag with 19hp kaw engine. Cranks and runs great with clutch engaged. When cutting it cuts great for a while, then sputters, losses power while backfiring through exhaust. Boggs down, then rpm picks up and levels out until you load it with another heavy cut. Then the symptoms reoccur. Have changed plugs and fuel filter. Any suggestions?
 

Luffydog

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  • / Engine stumbles with poping exhaust on a kaw 19hp engine
Take a good pair of pliers with rubber handles start engine and pull one plug wire off and see if it dies if it doesn't put it back on and pull the other off and see if it dies. Let us know what u find.
 

vintageman

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  • / Engine stumbles with poping exhaust on a kaw 19hp engine
Pulled plug wires separately and runs, doesn't die or stumble. Did this when cold and not under load. Will check again when it is hot and after being under load. Still think it may be a bad coil that acts up only when hot. What do you think?
 

Luffydog

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  • / Engine stumbles with poping exhaust on a kaw 19hp engine
Could be. Check your tank for any grass and debree when it gets low take filter off and blow little air back into the tank with cap off. Or take line loose and make sure you have good fuel flow sounds like it is stopped up in the tank or might have some water.
 

7394

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  • / Engine stumbles with poping exhaust on a kaw 19hp engine
Have you by chance recently adjusted the valves ?
 

vintageman

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  • / Engine stumbles with poping exhaust on a kaw 19hp engine
No, I have not adjusted the valve clearance. Had not considered adjustment, due to engine only having 143 hrs on it.
 

bertsmobile1

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  • / Engine stumbles with poping exhaust on a kaw 19hp engine
The first "in warranty" dealer service should check the valve lash.
Unfortunately many don't.
Things settle down after a few heating cycles so valve lash is generally wrong at whatever the first service interval which is why it is so short , usually 20 to 50 hours.
 

vintageman

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  • / Engine stumbles with poping exhaust on a kaw 19hp engine
I have a scag with 19hp kaw engine. Cranks and runs great with clutch engaged. When cutting it cuts great for a while, then sputters, losses power while backfiring through exhaust. Boggs down, then rpm picks up and levels out until you load it with another heavy cut. Then the symptoms reoccur. Have changed plugs and fuel filter. Any suggestions?

Engine runs while pulling plug wires separately, indicating good coils!!

Again,pulled plug wires separately while running. Placed screw driver in wire end to test spark from coil. One side had a strong spark. The other side was weak.
I replaced both coils and engine is back with normal power. Was advised by vendor that the new coils were an improved version from the old original ones. Stated that Kawasaki is fully aware of the faulty coils in the 19hp kawi engines. Evidently they have sold a lot of replacement coils due to failures.
 
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