Hi all,
So I recently acquired a 2002 Polaris Magnum 325 4x4 and I've got engine troubles. Would not start at all so I cleaned the carb and adjusted the valves. I got it to start. It will idle pretty good but as soon as I hit the throttle it bogs coughs and basically locks up and stalls. It kind of squeeks when it stalls. I took the belt and clutch off but still does the same thing. Any ideas why it does that before I tear it apart? Maybe a common problem?(hopefully simple lol)

Thanks in advance

 

Might seem a stupid question but do you have the air box and filter installed? If not that could be the reason for the bogging. If you do have it installed and it does this,then I'd check compression. Standard compression range on this model is between 70-90 psi because of the decompression device on the cam.

 

I did have the air box both off and on. I read that before and got excited that may be all it was but no luck. I will do a compression test and leak down while I'm there tonight. Just scares me with the churp it makes when it stalls abruptly.

 

Have heard that noise before. Hope it's not a piston squeal as it's seizing. Keep us updated.

 

Yeah that's for sure. It's weird because it doesn't idle to bad. I'll let you know what I come up with later.

 

so I finally did a compression test on the beast and with the good ole harbor freight tester i got 60 psi with the starter. I also did a leak down and got only a little bit more than 20% so i dont know if its the rings or not

 

Compression is on the low end at 60 psi,leak down high at 20% when the manual shows 10% max. Might be worth the tear down. Hope it's just the top end and the rod is ok as these had split rods like a car. Cranks could be turned,over size rod bearings installed, but the machine shop had better know what they're doing on this one if the crank is involved also.Dirt Cheap Yamaha, Polaris, Suzuki & Kawasaki OEM Parts & Accessories – Cycle Parts Warehouse Just happened to think about a couple I came across over the years that the slotted nut holding the lower timing chain gear in place came loose and was grinding against the back of the stator plate. If mine I'd pull the recoil,flywheel,stator plate and give a good look see.. Might be where the noise is coming from and causing the lock up? Plus this guy had a similar problem with the nut backing off and the crank sprocket eating away at the woodruff key and causing noise..

 

Well ik it's been a bit but I finally got the motor out and saying that it spun the rod bearing would be an understatement so off to the machine shop she will go hopefully with if anything just a new rod not a crank. Does anyone happen to have the specs for the crank rod and bore on this motor for me to give to the machine shop. That would be super helpful. Thank you. I'll be sure to keep an update

 

Specs are in the manual along with side to side play on the rod allowed.2002 Polaris Magnum 325 Service Manual PDF Download Rod has an updated part number which may be because of the problems that a few of these had on this. I had a couple Trail Boss 325s that spun bearings. Two over size bearings are offered,but if it's like the ones I got a hold of, the crank journals were damaged too far to grind down and I just replaced the crank assembly.Hopefully you can salvage your crank shaft. Dirt Cheap Yamaha, Polaris, Suzuki & Kawasaki OEM Parts & Accessories – Cycle Parts Warehouse

 

Thanks so much for the link to the manual. I took the rod crank and jug to the machine shop and of course as you said the crank journal was already at .02 and rod was whipped too so time for a new crank and rod. Bore luckily only needed to go .010 over.