I bought a 1997 xpress 300. It did not run. So I broke it down and found out it needed piston and rings. Piston was scored on the right side of it. That was the only spot that was bad. The rest of the piston looked good. So I replaced them. Put it all back together. the only way it would start is with staring fluid. But it did start up. And it ran good. but now the only way to get it started is with starting fluid. I could have it running for 20min shut it off and try to start it right back up and nothing. Starting fluid is the only way I am getting this thing started. I friend of mine told me to check the crank. So I pulled of the clutch. I the crank moves up and down. It needs new bearing. But could bad crank seal cause it to run that way too? does anyone know were to get the bearing and seals at? In a kit.

 

Have the cylinder measure and bored out to the next correct oversize piston. Doesn't do any good on 2 strokes or for most 4 strokes as far as just throwing another standard piston and rings back in. Clearances are tight on piston to cylinder and when any kind of seizure happens,time for a top end rebuild at least.Since you checked the crank shaft and it can move up and down,time for new crank bearings and seals also... While you're down that far I'd just do it right and install a new rod kit also.http://www.ebay.com/itm/Polaris-300-2x4-4x4-1994-1995-Connecting-Rod-Kit-3082790-/400938473707?fits=Make%3APolaris%7CModel%3A300&hash=item5d59cb98eb&vxp=mtr Plus you can get the three bearings and seals on ebay. A good machine shop can install the rod kit and crank bearings along with doing the bore job..Doesn't matter whether its for a 250/300 or year model as the crank bearings are the same for all.
http://www.ebay.com/itm/1995-Polaris-Trail-Boss-300-Crank-Crankshaft-Bearings-And-Seals-Kit-ALL-*****-/281741713481?hash=item41991d6049&vxp=mtr

 

The piston is 75.50mm the standard size is 74.50mm. It Is a .040" overbore. The piston I took out of it looked almost brand new. And it had tons of blow by. The kit that you showed me only have 2 bearings. I need 3 And all 3 have different part numbers. and the part number from the 95 does not match the 97. even the OEM part numbers do not match.

 

As far as the bearings you DON'T have to have the odd ball inner bearing that goes on the clutch side of the crank. You can have all three bearings the same.I installed plenty of them like this and a lot of aftermarket kits don't even offer that bearing. It's supposed to have allow better oiling between the two crank bearings,but never was proven to have done so..Plus the 250 and the 300 uses the same rod,only difference is the piston size.Don't just judge a piston by it's looks,have the cylinder measured as you're talking about thousands of an inch clearances here.Here's a good video on this and even shows the redneck way of using a feeler gauge toward the end..

 

The part numbers are (ZA-NTN-62/32C3)-(ZC-NTN-62/32C3) One has a bevel on the inner race. The other bearing is on the flywheel side. I can not get it off because of the worm gear for the oiler. but that part number is (NTN 6208)

 

You have to have a bearing separator behind the inner bearing,heat the worm drive gear up thoroughly and whack the bearing separator to remove the worm gear and bearing. Worm gear has to be heated back up to slip back onto the crank shaft.. ALL ***** kits uses the same bearings for all three,same as for the 250. Plus I had discussions about this over the years with several Polaris engineers and they basically said the same thing,all three bearings can be the same! If you want to order oem bearings and feel safer about doing that,that's entirely up to you. Here's another listing for the Express 300.http://www.ebay.com/itm/All-*****-24-1084-Crankshaft-Bearing-And-Seal-Kit-Polaris-Xpress-300-1996-99-/321798637599?hash=item4aecb1881f&vxp=mtr

 

That's fine I have no problem using all the same bearing. But all the bearing kits I have found only offer 2 bearings I need 3. And wene I heat up the worm gear. Do I get it red hot or just before red hot.

 

It's got to get pretty dad gummed hot for it to move. Same for the install.Have a good punch ready in case it doesn't seat fully against the new crank bearing. I just used a hot plate at work and heated em up for a good 10 minutes are so. A bearing separator is what I used,but I suppose a good puller would work also just as long as it could get a good grip on the bearing. This is the one I had,but plenty of cheaper $19 ones (that should last a time or two)are on ebay also.http://www.ebay.com/itm/SnapOn-Bearing-Separator-2-3-8-CJ950-/121713940452?hash=item1c56b757e4&item=121713940452&vxp=mtr Plus it makes it nice if you had a 1/2 plate steel table that you could work on like at the shop,but a good work bench or concrete floor can work ok.I got tired of trying to screw em down,so I just whacked the top of the separator and job done.. On the reinstallation of the worm gear I used the hot plate or a torch,for removal I just heated the gear up with a propane torch until it was smoking hot,made for easy removal.

 

Would the bearings for a 1999 Polaris trail boss 250 fit. I can get the hole set all 3 bearings and both seal for $43.99 on ebay here is the link. http://www.ebay.com/itm/161771567575?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

Look at the link above with the three bearings and seals.It's from the same supplier I believe. Your listing just shows two bearings on the pics? If it's got all three bearings and seals, then it's a good price..