I remember that my kit come with a pair of rings. They were the exact same diameter, but there was one that would not fit in neither one of the grooves. It was like it was barely too thick. I ended up breaking it, and ordering another set of rings. Exact same thing. One ring wouldn't fit in neither of the grooves. So i took the 2 from the different sets that for and used those. The ring gap seemed correct. Could this be a problem? They were the same size but i didn't have a dial caliper to judge the thickness. Both of the rings i used seemed to fit in the piston right. Are both of the piston rings supposed to be identical? Also of i pull the motor, what would be a reasonable rate for removing old bearings and installing new ones?

 

You never said what piston you used so I'm just guessing Wiseco. Wiseco usually has the same size rings on the old 250. Any piston that has a thicker ring,this ring(usually a darker color) should go on the bottom,thinner rings(usually a silver/chrome color) on top. Also marks on rings (N50,R50,etc ) always face up as the rings are tapered so they can "scrape" close against cylinder walls for a good seal. When the ring is just installed in the cylinder,the ring end gap should be between .009 to .018 max. Plus just to make sure, the the piston ring stops face the intake only as some people have installed pistons backwards. "IF" the noise is from the bottom end,the quicker you tear it down the better on being able to save the new piston and bore job. Not only do you need to replace the crank bearings,but you need to install a new rod kit on the crank shaft. Hot Rods are what I used the most of,even in place of Polaris parts because imo they are a lot better ! The crank has to be separated,new rod, lower rod bearing,spacers,and new crank pin installed,then the crank has to be balanced or "trued" as we called it. For this you need a 20 ton press,crank shaft holder,plus a dial indicator and truing stand OR just take it to a local dealer or machine shop.Just call and see what they charge since you're supplying the parts. The three (3) crank bearings you can get cheaper at any auto store or bearing house. Just use the "universal" number on the bearing. Hot Rods, Inc. OR you can go the cheap route on a rod kit. http://www.ebay.com/itm/Polaris-250-300-Connecting-Rod-Kit-Trail-Blazer-Boss/261197573773?rt=nc&_trksid=p2047675.m1851&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D261%26meid%3D9086869868299259411%26pid%3D100005%26prg%3D1088%26rk%3D1%26sd%3D120479811093%26

 

The piston rings did have a marking, I need to pull the cylinder and make sure I have them right. I can't remember if I put the markings up or not. I didn't notice the robs being tapered. I used the wsm top end kit. If I had the rings upside down, wouldn't they not fit in the cylinder? Both of the rings were the same "color"

 

Yes the rings can fit marks up or down on the piston and in the cylinder. It's hard to notice the bevel on the rings,that's the reason they're marked..

 

Could that be why I couldn't get the other rings to fit?

 

Who knows? They could have sent the wrong rings for this piston the first time?? Just check out the ones you have installed now..

 

Both pairs had 1 ring that wouldn't fot right. I couldn't push it all the way in, and however far I did get it to go it got stuck. So I just used the 2 that fit, but I didn't pay attention to how they faced. Can you removed the whole motor without pullib the jug? I'm going to try and pull the motor and put it on the workbench and break it down. In a nutshell, how do I get the whole motor out? Undo motor mounts, exhaust, pulleys, belt, inner cover?

 

Yes you can pull the whole engine out as an assembly. You have to remove the exhaust,clutches,motor mounts,carb,plus what I did was to remove the flywheel and stator and tucked them inside the frame rather than unplugging all the wires. Makes it simpler when you reinstall the engine. You have to twist it around a little,but it'll come out toward the clutch side ok.

 

Ok, so I got the bottom end done, put it back together, luckily there was no top end damage. I did have a ring upside down though. I rebuilt the carb today, put a 155 jet in it, and a clamp on unifilter, with a black/white primary spring. I'm wondering if I have the idle air set right. How many turns is it supposed to be? I started at 1.5 turns, then I couldn't tell a difference between turning it in and out. It doesn't sound like a 4 stroke, so the idle difference is hard to tell. How do you adjust it? And how do I adjust the choke?

 

Normally 1 1/2 to 2 turns out from a lightly seated position. You wont notice usually a great deal of engine change since this is an air/fuel screw,not a fuel/air screw that's on 4 stroke engines and more critical to engine idle. Just start at 1 1/2 and gradually go up while checking throttle response. If it starts to hesitate,just go back down. Stock jetting shows to be a 145 main jet (from sea level to about 3000 ft or so) so it might be over kill on the 155 main depending on your altitude,but do a plug chop test after you get it running properly.If the plugs dark,drop back down to the 145. The choke adjusts at the carb. Loosen the lock nut on the cable adjuster,turn adjuster in or out until you have about 1/8" or so slack on the choke lever,then tighten the lock nut.