Try taking the snoot off the airbox

 

I've been having the same issue with my '96 Magnum. I just replaced the needle jet, jet needle, main jet and the diaphragm (mine was siliconed together). I started it up and it ran like crap.[img]i/expressions/face-icon-small-confused.gif[/img] My reverse limiter decided to take a dump. I unplugged the black wire from it and it'll rev all the way up now. It hasn't done that since i got it. You could actually see the wear on the needle jet. I revved it a few more times and the throttle cable broke![img]i/expressions/face-icon-small-frown.gif[/img] I stole the one from my dead '86 Kawasaki Bayou 300 and modified it to fit. [img]i/expressions/face-icon-small-happy.gif[/img] I'm going to ride it around tomorrow and make sure it's alright. I'm supposed to trade it off on Monday for a 2000 Trailblazer and a 2001 Scrambler 400. Neither of them run right and the owner of them doesn't like 2 strokes. I checked and they both have good compression, so it shouldn't be too tough to get them up and running.

 

I have replaced the jet needle, needle jet, main jet (37.5- i thought it was running too rich) floats, inlet needle valve/seat, all O-rings, in addition to all the other 'easy' possible solutions. Still, no power under load with a goodly bit of backfire through the carb. Solution? The center lobe (exhaust) on the cam is worn down (just like the number one exhaust lobe on the GM 350 used to do at 80k miles). This is only detectable by removing and inspecting the camshaft; valve lash and/or a compression check won't catch it. The good news is that if you've removed your carb, then getting to the camshaft isn't all that difficult; it can be done without removing the engine. The bad news is that a new camshaft assembly is around $250. Proper alignment prior to removal and during installation is important, as is the use of assembly lube on the lobes. Having a service manual is recommended. The service tech (Terra Haute, IN. An excellent shop) advised that this is a fairly common problem with these engines, having to do with inadequate lubrication and usually the result of improper oil or infrequent oil/filter changes. I'm wondering if Crane Cams has anything redical on aftermaket for it.....

1996 425 Magnum 6X6 (subject of post)
2005 800 Sportsman

 

Aaen has a replacement and so does WEBB cams

 

<div class="FTQUOTE"><begin quote>Originally posted by: clazy_chollie

I have replaced the jet needle, needle jet, main jet (37.5- i thought it was running too rich) floats, inlet needle valve/seat, all O-rings, in addition to all the other 'easy' possible solutions. Still, no power under load with a goodly bit of backfire through the carb. Solution? The center lobe (exhaust) on the cam is worn down (just like the number one exhaust lobe on the GM 350 used to do at 80k miles). This is only detectable by removing and inspecting the camshaft; valve lash and/or a compression check won't catch it. The good news is that if you've removed your carb, then getting to the camshaft isn't all that difficult; it can be done without removing the engine. The bad news is that a new camshaft assembly is around $250. Proper alignment prior to removal and during installation is important, as is the use of assembly lube on the lobes. Having a service manual is recommended. The service tech (Terra Haute, IN. An excellent shop) advised that this is a fairly common problem with these engines, having to do with inadequate lubrication and usually the result of improper oil or infrequent oil/filter changes. I'm wondering if Crane Cams has anything redical on aftermaket for it.....



1996 425 Magnum 6X6 (subject of post)

2005 800 Sportsman</end quote></div>

 

I have replaced the jet needle, needle jet, main jet (37.5- i thought it was running too rich) floats, inlet needle valve/seat, all O-rings, in addition to all the other 'easy' possible solutions. Still, no power under load with a goodly bit of backfire through the carb. Solution? The center lobe (exhaust) on the cam is worn down (just like the number one exhaust lobe on the GM 350 used to do at 80k miles). This is only detectable by removing and inspecting the camshaft; valve lash and/or a compression check won't catch it. The good news is that if you've removed your carb, then getting to the camshaft isn't all that difficult; it can be done without removing the engine. The bad news is that a new camshaft assembly is around $250. Proper alignment prior to removal and during installation is important, as is the use of assembly lube on the lobes. Having a service manual is recommended. The service tech (Terra Haute, IN. An excellent shop) advised that this is a fairly common problem with these engines, having to do with inadequate lubrication and usually the result of improper oil or infrequent oil/filter changes. I'm wondering if Crane Cams has anything redical on aftermaket for it.....

To follow up....

The replacement Polaris camshaft for the 1996 425 Magnum has been redesigned. The new shaft has an oversized oil journal on the left end, where the oil is fed to the shaft. The exhaust lobe, which before had one small oil hole, now has two bigger oil holes. This would indicate that it is a common problem that Polaris is aware of and attempting to resolve. For those of you with the loss-of-power problem, check the oil filter and reservior magnet for fine metal shavings; they came from the exhaust lobe of your camshaft. Replacing the camshaft is much easier than removing and rebuilding the carburator. Be sure to secure the timing chain with a wire after you remove it from the cam gear, so it doesn't fall down into the engine. The shaft slides out to the left. Make sure the TDC mark on the flywheel is aligned AND (there are two TDC positions possible) that the cam lobes are pointed down (toward the piston). Be sure to replace the rocker arms as well; they're $165 for the set at Babbits ATV parts online. Mark or remember the alignment of components upon removal, and replace them accordingly. The replacement camshaft comes as an assembly, with the compression release already installed. If you don't have a service manual to specify the spring position on the compression release, make note of the position when you first get the replacement camshaft, in case it gets jarred out of position while it's sitting around waiting to be installed.

Haulin' wood again in Indiana...