Hello, I am a new member and i hope that i am posting this in the right spot.
3 days ago i purchased a 1996 Polaris Magnum 425 4x4, automatic with on the fly 4x4. It was pretty decent. At low end it would kick of bog down and sputter just a bit than it would pick up and go. Today when I went to ride it it kept losing considerable power, so i nursed it back to the house where it would die at idle. Than it would proceed not to even start. I took it apart and cleaned up the spark plug, and took the carb apart and cleaned it up as well, though both looked decent. I even went as far as removing the fuel pump and disassembling it and making sure there was no trash in it. Put everything back together.... no dice, itll start after a good bit of winding and will stay running as long as you hold the throttle wide open (although it only sounds like its idling) as soon as you let off itll sputter and die. it has zero power. as i said full throttle is like idle. Can anyone help shed some light on this issue? thanks in advance.

 

A manual would help you a lot on this.DOWNLOAD 1996-1998 Polaris ATV Repair Manual ALL MODELS - Download ... First thing I'd do is check that you only have about 1/8" slack at the thumb lever. Too much slack and the internal etc contacts can touch and die at an idle. Cleaning carbs don't always help.Kits are the best way to go and you can eliminate the carb as a problem. Plenty are available on ebay.http://www.ebay.com/itm/NEW-SHINDY-CARBURETOR-CARB-REBUILD-REPAIR-KIT-FOR-POLARIS-425-MAGNUM-1995-98-/291286919632?pt=Motors_ATV_Parts_Accessories&hash=item43d20da9d0&vxp=mtr This model also was in the range that had cam problems. The early 425 and 500 engines exhaust lobes could be ground down by using the wrong viscosity oil,in frequent oil changes,plus part of the blame could be on soft heat treatment of cams. I'd pull the cam cover check the center(exhaust) lobe for any wear. If the cam lobe appears to be okay,check the valve clearance. .006 intake and exhaust. Here's one that was worn down. Bad Cam Pic - ATVConnection.com ATV Enthusiast Community
Plus clutch problems can cause similar type problems you're describing,such as belt wear/stretch or rear clutch ramp button wear. Again the manual is worth the 5 bucks.

 

it ran great for 2 days than today after just a few minutes of riding it when it had loss of power (as in bogging down, not eletrical) and than died.... would cams or carbs cause this?

 

Either can! Just a process of elimination. Check out the cam and valve clearance first. If this area checks out,I'd order a carb kit if you have good spark.Plus you can pull the fuel line from the carb and crank the engine over to see if the fuel pump is pulsing fuel through the line.Check the fuel tank vent line for any kinks,plus you can remove the cap and see if it solves any bogging because of vapor locking. Again clutches that have worn parts or belt can cause the same type symptoms,loss of power. Several different areas that you just need to check out.

 

we did pull the fuel line from the carb but nothing came out when cranked it, but there was vacuum coming from the carb so i figured the carb would suck the fuel.... is that not the case?

 

I just contacted the person i purchased it from, he said he recently built the carb, so im assuming the next step would be the cam/valve. Here is a silly question.... how do i measure the gap?

 

Then that could be the problem.. The fuel pump gets it's vacuum from the hose on the carb carb leading to the "P" marked nipple on the fuel pump. Check that this hose is ok and connected. Pull any fuel filter off the line going to the carb also. If you determine it could be a fuel pump,you can find them on ebay or here. Item #5.Dirt Cheap Yamaha & Polaris OEM Parts & Accessories – Cycle Parts Warehouse

 

Okay so just to make sure I understand. Take the line off of the carb and try to crank it.... And fuel should come from the hose I removed from the carb?

 

Yes,just crank the engine over. If fuel pulses from the line the fuel pump is okay. Pull the cam cover,inspect the cam lobe,have the piston at TDC. The cam sprocket alignment pin will be dead center of the head,cam lobes pointed down.You can pull the 14 mm plug on the recoil if you wish(not necessary) to see the tdc mark on the flywheel.Then you can check/adjust valves.

 

Okay well no fuel spurts out so I'm gonna guess that is my issue... Though I did remove and range apart the fuel pump I saw no trash or anything and it looks like the fuel pump is pretty new... I'll buy a new one and go from there..... Can I connect the fuel line straight from the tank to the carb to see if that's the problem?