Think you found the problem on hard starting along with tight valves.. Make sure the ball relief area isn't damaged on the cam or rocker arm scarred. If it isn't you can replace this 60 buck part and have less labor involved or opt for just replacing the whole cam.Polaris 425 Xpedition 400 500 Sportsman Ranger Mangum Cam Camshaft 3086212 | eBay

 

Thanks OPT. Do I have to pull the camshaft to check the ball relief area? I was hoping to avoid that if possible.

 

No,just turn the engine over until you see the hole. The bearing will drop away,but if the area supporting the ball bearing is worn or gouged the cam may not last long. If it appears ok just install the new detent lever.

 

The ball seemed to be moving freely, but thought we should take cam out for a closer look anyway. Found a significant wear mark on the exhaust rocker arm over the bearing location. Ordered a new exhaust rocker arm and new cam.

OPT - question about something you stated over on this thread in post 31...
https://atvconnection.com/forums/pol...-camshaft.html

1. You mention oil and filter change - is that just because the top end is opened up and could have gotten debris in there?
2. You mention clamping the tank vent line. Assuming this is the crankcase vent line that goes from the cam sprocket cover to the airbox? What's the purpose of clamping this line?

Thanks!
-mc

 

Usually when most cams are damaged a lot of metal is floating around. Just standard practice to change oil and filter and clean the screen filter at the the oil tank to remove any particles. When you remove the oil lines you need to prime the oil pump up quickly especially with a new cam. This is where you need to pinch off the oil tank vent line which shuts off air and allows the pump to prime up faster to get oil to the top end quicker. When you release vice grips from the vent line a hiss is heard fairly often when air is purged. The Expedition is a different engine in that it's a wet sump and carries oil internally. Not really necessary to pinch off the crank case vent line. Plus with 5 1/2 quarts of oil it may not need to be changed.. Gets expensive if you do. Good that you're replacing the cam and rocker arm if you notice any damage..

 

Got the new cam and rocker arm in there yesterday and all buttoned up - thanks for help with that. But, lo and behold, it still won't start when cold.

Symptoms again... above 40F it starts great, below 30 or so and it will fire for just a second or two when you choke it, but it dies right away. Then it won't fire again for a while. 5-10 minutes later and you can repeat the routine.

I'm wondering if it's simply a choke issue... Maybe we don't really have a choke here??? Could we have goofed something up when putting the carb back together. We screwed in the choke cable on the carb, and adjusted it to about 1/8" at the lever. Thoughts?

Here's a quick video of it...

 

Always check for spark first. Just ground the plug at the head and check. If you have good spark,good fuel supply from the fuel pump,then sounds like you have to check back into into the carb.Looking over your first post you've done everything except replace the stator. You might look at this post and see if it could be your problem,especially if you can pull start it..http://forums.atvconnection.com/pola...ml#post3155476

 

Can't tell from video, but the choke lever has 2 positions. When straight out, which I see in video is position 1 is probably around half choke. There is ramp on choke lever and if you flip lever to right will lock into position 2 which should be full choke if everything is adjusted right. I know on mine it will start when 40 or above and be little hesitant like u stated yours is when in position 1. When it gets cold it will not start in that position must use position 2. Hope this helps can't tell from video if you flip lever for full choke.

 

Thanks. We've been through adjustment of the choke lever with no impact - which I believe is really just to ensure there's no choke when the choke is in the off position.

I'm able to start the machine in the cold with starter spray in through the air box (with air filter off), so I'm back to the carb enrichment circuit...

We rebuilt the carb at the beginning of this project, so if I take it apart again, I'm not exactly sure what I'm looking for. The enrichment circuit looks pretty straightforward, but is there something I could have missed in there? ... or anything to pay special attention to when I open it back up?

I noticed aftermarket carbs on ebay for $120. Seems silly, but I'm wondering if that would be simpler when I don't know what I'm chasing.

 

Again look at this post on not being able to start with the electric starter. If you just tap the pickup coil over a tad,may improve starting.no spark to plug when using electric starter - Page 3 - ATVConnection.com ATV Enthusiast Community If this doesn't help,check the ohms from the pick up coil. Should show around 97 ohms resistance. If out of range this could be the problem. If in range might be time to check the stator itself. If the stator specs check out,then I'd consider the cheap ebay carb. Plus I do hope you have the air box and filter on or that can be a problem on starting.