1976 arctic cat backfire issue

G man 1993

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Hi . wondering if anyone can help me out with my problem. Just bought this sled, was running fine when I got it, rode it a few days,then it started to backfire, dont know a whole lot about sleds. Looked it over and found one carb boot was cracked so I replaced it. But its still backfiring and hard to start. Any suggestions what to try next !?
 

TROLLCAT

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make sure spark plug caps are not loose if they are replace them and a new set of spark plugs
 

Lund

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Hi . wondering if anyone can help me out with my problem. Just bought this sled, was running fine when I got it, rode it a few days,then it started to backfire, dont know a whole lot about sleds. Looked it over and found one carb boot was cracked so I replaced it. But its still backfiring and hard to start. Any suggestions what to try next !?

WOW, that is an issue best takin care of by a hands on tech. Why "1976", the age of the sled is the problem, there are so many things that can cause issues when components get old.
That being said a 2stroke is a 2stroke and i hope you understand them enough to know what your doing.
First thing is understanding causes of back firing in a 2stroke, generally it is caused by an inability to burn the fuel mix. Either because of malfunctioning ignition system or an over fueling fuel system. Plus in your case a worn out motor, like worn out rings.
Back firing is seldom and almost never caused be a lean situation, such situation (lean) will cause a 2stroke to over speed (rev) like running out of gas on a chainsaw and lead to eventual melt down.
Back firing on a lean condition is a 4stroke issue, completely opposite to a 2stroke. Many folks get these symptoms confused and chase their tails.
So yes the crack boots would had never cure the issue, though not a bad idea to replace as they are old.
 

Lund

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Basic things you might want to check in order of importance;
-Spark plug conditions, is one wetter then the other?
-plug wires and caps, condition and fitment.
-Choke plunger and cable, dumping extra fuel?
-Compression?
-carburetors, cleanliness and float level, would be too high. Needle seat and seat needle conditions.
-Reed valves.
-Fuel pump pulse hose, is there fuel in it. Answer should be NO, no fuel in pulse hose.
-Ignition can cause weak spark, failing spark and out of timing, wiring, primary coil, secondary coils, stator, CDI?
All these symptoms(issues) can cause an over fueling and collection of fuel that causes back firing.
And i'm sure i missed some.
 

mountianguy

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Hi . wondering if anyone can help me out with my problem. Just bought this sled, was running fine when I got it, rode it a few days,then it started to backfire, dont know a whole lot about sleds. Looked it over and found one carb boot was cracked so I replaced it. But its still backfiring and hard to start. Any suggestions what to try next !?

If it is backfiring out the exhaust it is most likely a fueling problem. If the backfire is coming through the intake most likely timing. 1976 was the first year for the Suzuki Spirit engine, nicasil cylinders and a decent engine for reliability. I would remove the carb and do a through cleaning and inspection, that wont hurt even if its not the problem. make sure the needle and seat are working right and all jets and passages are clean. Then adjust the choke and throttle cable to spec. Check all fuel lines and filter in the tank if it has one, replace the pulse line and rebuild the fuel pump. All this can be done at a low cost.
 
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