I picked up a '95 425 Magnum last night. The bike hasn't ran in a couple years. The owner said it wouldn't start and they replaced the ignition switches and it still wouldn't start, so they put a new cam in it thinking it might be the culprit. They could still never get it started. I brought it home, bypassed the fuel pump, squirted ether to it and it fired right up.

However, its building a LOT of crankcase pressure. The only crankcase vent I can find is on the back of the cylinder right below the timing tensioner. This vent is pushing a LOT of oil out and into the air box. I pulled the vent tube and put it in a bottle. After about 20 seconds of running, it put about half a quart of oil in the bottle. When you shut it off, its still releasing crankcase pressure for 5-10 seconds. Is that the only vent line these engines use? What could be causing so much pressure?

I haven't checked compression yet, but that is the first thing on my list. I wondered about rings being stuck from sticking, but its not smoking at all out the exhaust, and plenty of air is leaving the exhaust so I don't think its an exhaust restriction.

Also, after starting it 7-8 times and using the key to shut it off every time, the last time it was running, the key switch, nor the kill switch would kill it. When you turn the key off, the speedo light would turn off, but the bike wouldn't shut off. I am thinking this is linked to their original problem. Any ideas?

 

Also, I checked the oil pump line to the tank to make sure the pump is scavenging oil out of the crankcase, and its pumping out fine.

Oil level was low when I started, so I added some to the full line. After running a bit and oil blowing out the vent, the level was down to the tip of the dipstick.

 

160 psi compression, so I don't think its a ring issue.

 

Check all the grounds, Polaris is not known for there wiring cleaness. I had a 400 scrambler and chased wiring problems all the time till I got rid of it.

 

<div class="FTQUOTE"><begin quote>Originally posted by: Ernie660R

Check all the grounds, Polaris is not known for there wiring cleaness. </end quote></div>

That's no joke. That is the least of my worries right now though.

My main issue is the fact it keeps filling the air box with oil.

 

Check to see if you have the proper oil level. Some times an excessive anount can do the same thing. I know on my cannondale the manual said 2 quarts but some of the engine builders told me only 1 1/2 quarts.

 

<div class="FTQUOTE"><begin quote>Originally posted by: Ernie660R

Check to see if you have the proper oil level. Some times an excessive anount can do the same thing. I know on my cannondale the manual said 2 quarts but some of the engine builders told me only 1 1/2 quarts.</end quote></div>

The oil level is all over the place. I am starting to wonder about the check valve in it. I am about to pull it out and check it.

 

I pulled the check valve, and everything seemed fine. So I drained the oil. The crankcase had a LOT of oil in it. Owners manual said there should be about 1 cup in the crankcase. I drained over a quart out of it. The oil tank had about half a quart in it. I refilled the tank with 2 quarts per owners manual spec, and started the bike back up. Within about 15 seconds of running, oil start blowing out the crankcase vent again. I checked the dipstick and its not showing anything.

 

Bump

 

160 psi seems awful high, the book on my 500 mag says its should be between 60 and 90 maybe an exhaust valve is not opening all the way. my buddy has a 425 i'll ask him about it when he gets back in a few days. good luck