Magnum 425 sputtering and backfiring
Jan 24, 2008 | 09:54 PM
#1
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Trailblazer
Joined: Oct 2007
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Magnum 425 sputtering and backfiring
I trying to help a friend fix his 1995 Magnum 425 2x4. It starts and idles fine, but if you give it any gas above 1/4 throttle, it starts missing and sputtering and it will occaisionally backfire loudly out the muffler. I replaced the spark plug and cleaned the air filter only about a month or so ago (I usually do the maintenance on the quad). It is also MUCH WORSE WHILE IN GEAR. The greater the load, the worse it does it. It doesnt seem to matter if the choke is on or off. Is this a fuel issue or a ignition issue? What should I do? TIA
Jan 25, 2008 | 12:57 AM
#3
Trailblazer
Joined: Nov 2007
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Magnum 425 sputtering and backfiring
I have the same problem... I ordered new nozzle, jet needles, and few other internal carb parts. I hope this will fix it, I will post my results in the next week or so after I do the install. I too have read that the cam could be the issue. Are you fouling spark plugs easily?
Jan 25, 2008 | 09:26 AM
#4
Pro Rider
Joined: Jun 2005
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Magnum 425 sputtering and backfiring
Souunds like the cam but check to make sure the etc is adjusted correctly and there isnt gas in the oil, sometimes the needle and seat go bad and fill the crankcase with gas. Maybe clean the carb.
Jan 25, 2008 | 12:59 PM
#5
Trailblazer
Joined: Oct 2007
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Magnum 425 sputtering and backfiring
My '96 did the same thing when I got it. It got worse when it warmed up. I got lucky. The valves were adjusted way too tight and weren't closing all the way. I'd check that first and make sure the lobes on the cam aren't flat.
Jan 25, 2008 | 01:59 PM
#7
Trailblazer
Joined: Oct 2007
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Magnum 425 sputtering and backfiring
When you take the rocker cover off to check the valve adjustment, just look at the cam lobes and make sure they arent flat.
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Jan 25, 2008 | 07:48 PM
#8
Quad Patrol
Don't let the hp numbers fool you. Its all in how you get it to the ground. Clutching clutching clutching!
Don't let the hp numbers fool you. Its all in how you get it to the ground. Clutching clutching clutching!
Joined: Apr 2000
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Magnum 425 sputtering and backfiring
<div class="FTQUOTE"><begin quote>Originally posted by: tedsxb
How does a cam go bad? I have never heard of a cam going bad, i didnt think it was possible!! How do you check if its bad?</end quote></div>
In the early-mid 90s Polaris had an oil problem to the topend that ate up cams in a hurry.This is the reason for the 0w40 synthetic oil and frequent oil changes.
How does a cam go bad? I have never heard of a cam going bad, i didnt think it was possible!! How do you check if its bad?</end quote></div>
In the early-mid 90s Polaris had an oil problem to the topend that ate up cams in a hurry.This is the reason for the 0w40 synthetic oil and frequent oil changes.