High speed surge

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blownengine

New Member
#1
#1
I have a 5 horse power tecumseh that surges at full throttle. It came off a very old snowblower. Circa 1976 i believe. Anyway is sears number 143-665082, Serial number 8142B.It starts and idles fine, accelerates hard, but surges at top speed. The spark plug always comes out black. It runs the same way with the air filter off too.
When you let off the throttle the exhaust pops and farts a ton as it slows down.
The only time the plug isnt black is when i turn the main screw in to 1/2 turns out. But then it surges worse and wont accelerate.
I have tried cleaning the carb three times now. The third time i removed the welch plugs and soaked it overnight. This morning i blew it all out and re assembled.

Any ideas?
Thanks, Dan
 
Austin T

Austin T

New Member
#3
#3
I'm guessing your running it governed then? have you tried revving it manually with your hand and seeing what it does at full throttle (not to overev it) sometimes it could just be the governor's fault.
 
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minibikedude

minibikedude

Active Member
#5
#5
Is the engine burning oil. The black plug indicates that it is running rich unless there black crud stuck to it than its burning oil too. I have a Tecumseh carb off a HSSK50 that I,m not going to use, I could sell it too you if you think it is the carb. The one I have has the primer bulb remote located. Or you could replace it with a 20mm carb like I did on my Hustler, I have pictures under my photos, I will never run another stock carb again it runs so much better.
 
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blownengine

New Member
#6
#6
Wow sorry i ever doubted you Austin! Upon closer inspection i found the governer was the culprit of the surging. And now that its gone the engine runs amazing. I was originally planning on keeping the governer because the frame its on is super small and i didnt want to go too fast. But o well:wink:

Also the engine magically seemed to stop running rich:eek:ut: It still backfires alot when i let off the throttle but ill ignore that. Besides, it sounds cool:thumbsup:
 
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blownengine

New Member
#7
#7
With that being said, can anyone tell me the correct spark plug for this engine? (143-665082, Serial number 8142B) I want to make sure i have the right one
 
cncsparky

cncsparky

New Member
#10
#10
blownengine said:
With that being said, can anyone tell me the correct spark plug for this engine? (143-665082, Serial number 8142B) I want to make sure i have the right one
Click to expand...
Can you recheck the number? I wasn't able to cross 143-665082. I found a 143-665072 thats a HS-50. It calls for a RJ-17LM plug. Do you know if its a points or solid state ignition?

Tom.
 
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blownengine

New Member
#11
#11
I checked the numbers and they definitly are 143-665082. It has points ignition. And it look almost identical to the other HS-50 i have. Someone on another forum told me my engine was circa 1976 and might no longer be listed because of its age.
 
cncsparky

cncsparky

New Member
#15
#15
I was doing some cross referencing at sparkplugs.com and can only find the j17lm listed for the HS50 engine :confused: . In the end, plugs are cheap. You might try several different ones to see if there's a difference.
 
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blownengine

New Member
#16
#16
I have both kinds of plugs lying around. If i tried them both what would i look for. Would the "correct" plug have a more brown/tan color then the "inncorrect" plug?
Since the plugs are so close would i really feel a difference in the power or acceleration?
 
cncsparky

cncsparky

New Member
#17
#17
Doubtful you'd see any difference with the plugs mentioned. Running too hot or too cold of a plug would affect performance, tho, and could damage the engine.
 
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