Greetings everyone. Thank you for the wealth of knowledge I've been able to pick up around here.

My father-in-law had a 2000 Polaris 425 that had a broken rear axle and he parked it in a barn about 5 years ago. He gave it to us and it's been a restoration project for the last 6-8 weeks. Everything is pretty much good to go, but it's been a lot more than a busted axle:

Full Service manual
new battery
new ignition switch (no key)
new kill/start switch (was bad)
oil change (5+ qts!?!)
air, oil, fuel filters
spark plug
rebuilt carb (float was stuck) & adjusted
Valve adjustment
new front brakes & rotors
gearcase fluid change
replaced rear axle & bearings
replaced side panel
new tires
fixed AWD (https://atvconnection.com/forums/pol...ml#post3304943)
fixed speedo (KA7OEI's blog: Repair of the speedometer on a Polaris Sportsman 500 4-wheeler)
replaced wheel speed sensor
repaired reverse actuator with a motor I bought off of Digikey

AND FINALLY IT ROCKS for the last couple weeks!!!! (when it's warm out... argggg)

The last issue I think we're up against is that now that it's getting colder in MN, when we go to start it, it takes a little choke for it to fire, it runs for 2-3 seconds and dies. If you're lucky it will give you another chance right away. But that's it. After that, it needs 10-15 min before it will give you another chance and fire again. I really can't get it to start sometimes, and it's absolutely frustrating. Runs and starts like a champ once it's warm.

Any suggestions on where to start looking???

THANKS!

 

If you've positively eliminated any carb or fuel delivery problems(fuel pump) intake manifold good, no cracks,my first suggestion is to check the cam compression release mechanism to see if the small return spring possibly might be broken.This can make one a bear to start if it has.Plus another area while you're at it is the exhaust cam lobe as it shares the same cam as the Magnum 425 and early Sportsman 500. Wear on the exhaust lobe was a common problem on these and could effect starting and running.Like I mentioned previously We only sold about 3 of these machines and don't have a good reference as to cam failures.I know it's nothing you want or like to hear after all you've had to do and accomplish..By the way good job if you were able to repair a dead speedo.. Seems like 2 of the 3 we sold had to have the reverse actuators replaced also..

 

I had not checked the fuel pump... I need to do that. Thank you!

 

Just pull the fuel line at the carb and crank the engine over. Should be either a steady or pulsing stream of fuel if the pump is ok. Don't overlook a stopped up fuel filter also. Pumps are cheap now if one is needed.Performance Fuel Pump for Polaris Xpedition 325 425 ATV Quad Fuel Pump | eBay

 

Fuel pump appears to be fine... it gave me a pulsing stream. And then I tested vacuum on the pump and it held it fine.


Assuming I still had my problem, I pulled the air filter off and started it with a shot of carb spray. Fired right up and has kept running, no issues. I thought it might fire up, but die after a few seconds... ... but it kept running.


So I'm wondering if by pulling fuel lines off and turning the gas valve on/off/reserve, etc... wondering if there was a blockage or something that may have sprung free?


We'll see if/how it keeps running. I've got a pump coming just for grins ($10!) and will probably blow out the fuel lines & valve when I put that in there.

 

Gremlins... Hate them little buggers..

 

I'm back at this again... Spring is fine, but the service manual says to replace the compression release shaft if there's any wear. Obviously wear here. Is this enough to cause my issue?

 

Got back into this today... the behavior is very persistent... If it's under about 30 degrees F, it will fire up for a couple seconds and die and then you can't get it started again. Above 40 F, and you can start it - it's a little delicate in between 30 and 40. Once it's warm it runs and starts like a champ.

1 - The compression release return spring wasn't broken, but the shaft of the release is worn more than I'd expect. Could this cause the issue?




2 - Opened up the valve cover (removed plastic & gas tank this time - SO MUCH EASIER!) as well... I checked the valve clearances, and I had to really push the 0.006 feeler to get it to go in. Wouldn't even make it in on some of them. On one of the exhaust valves, I barely got my 0.004 in there. I'm guessing these wouldn't change that much in the 50 or so miles since I adjusted last, but I probably just went too tight last time.

3 - The exhaust cam lobe looked good to me - very similar to the intake lobes and nothing like the pictures I've seen on the internet of bad ones.

So any thoughts on 1 and 2 and if they'd affect this? Or thoughts on where I might want to look next???

 

NOTE - this is my third time trying to post a reply in the last three days, every time it says the post needs to be approved by a moderator, but apparently that's not happening. Wondering if I'm getting that because I'm trying to embed images in the post? I'll try without this time...

Got back to this a few days ago. Took front plastic and gas tank off - so much easier to see/get the top end!

1. The compression release spring is in good shape, but the shaft of the lever is rounded off a bit on one edge where the camshaft ball engages it. Is that typical? Could it cause issue? I have a picture I've tried to post, but I'm guessing that's why I'm getting flagged for moderator approval, so I won't post it this time.

2. Camshaft exhaust lobe appears fine. This is a 2000, so as I understand, it could be at risk for rounding off. Lobe appears very similar to the intake lobes.

3. My valve clearances were tight. I couldn't get .006 between some of them, and one of them was extremely tight even with a .004. We've only put 50 or so miles on it since adjusting them last, so I'm guessing I did them too tight last time. All are at 0.006 now. Any thoughts on the impact that could have?

4. Every time I've done a compression test, I've been around 60PSI. Service manual says 50-90, so I haven't been concerned. Sound about right?

5. I have a leakdown tester and I've been wanting to do a leakdown test... When I used to do it on my 2-stroke v6 outboard, it was easy to clamp the flywheel in place and put 100PSI into it. Any thoughts/notes on the best way to do that with this motor?

THANK YOU!

 

Pictures should be available now. Sorry for the delay, just caught us all enjoying the holidays.