Thanks for that list OPT. Ive been trying to round up one on ebay. Everybody seems to want big money for them.


I have found a reasonably priced inner and outer clutch cover in great condition off of a Polaris Xplorer 400. The parts listings show that the outer cover is the same, but the backing plate is a different number than what came on mine. Do you happen to know if an Xplorer 400 backing plate would work on this 300 Xpress?


And yes, it does seem to have some exhaust leaks. I may have to try the RTV trick. I ran it a little the other day after cleaning out the fuel tank and it either quits smoking as much once it gets good and warm, or the fresh gas took care of it. Either way the engine seems to run great, the frame looks good and the plastic is solid, but they've neglected some mechanical issues so im trying to get that in order.


I checked to see if it was trying to charge(there is a bad battery on the machine) with it idling the other day and got no voltage at all. Someone has messed with the voltage regulator wiring where the regulator would plug in. Im hoping either the wiring connections are loose or the regulator is bad since they seem to be cheap enough. Either way, im pretty sure its not trying to charge at all. Ah, the joys of an "initially cheap" project. Oh well, my buddy that's buying it is just glad that it will be gone over and in good shape when he gets it and I think he'll be happy with it once its together. It'll probably get a little bit of a workout hauling firewood for him this winter. He's coming over Saturday so im trying to get all the parts I can rounded up so we can knock out most of it.

Thanks!

 

Some models do exchange like the 97 model 300 Express and Explorer 400 and several other models. Any difference would be maybe one outer cover hole wouldn't line up with a different backing plate. Usually the rear of the backing plate would mount to the transmission ok.

Usage : 2200790 Inner Cover

Year Product Model Assembly
1998 ATV SPORT 400L CLUTCH COVER Sport 400L W98BA38C (4947234723C003)
1998 ATV XPLORER 400L CLUTCH COVER XPLORER 400L W98CC38C (4945414541C004)
1997 ATV XPRESS 300 CLUTCH COVER (400L) XPRESS 400L W97CA38C (4939603960C008)
1997 ATV XPRESS 400 CLUTCH COVER (400L) XPRESS 400L W97CA38C (4939603960C008)
1997 ATV TRAIL BLAZER CLUTCH COVER (SPORT) Sport 400L W97BA38C (4940124012C005)
1997 ATV SPORT 400L CLUTCH COVER (SPORT) Sport 400L W97BA38C (4940124012C005)
1997 ATV Big Boss 6x6 400L CLUTCH COVER BIG BOSS 6X6 400L W97AE38A (4940814081C007)
1997 ATV BIG BOSS 6X6 400L CLUTCH COVER BIG BOSS 6X6 400L W97AE38A (4940814081C007)
1997 ATV SCRAMBER 400L CLUTCH COVER Scrambler 400L W97BC38C (4939893989C006)
1997 ATV SPORTSMAN 400L CLUTCH COVER Sportsman 400L W97AC38C (4939673967C006)
1997 ATV XPLORER 400L CLUTCH COVER XPLORER 400L W97CC38C (4939753975C004)
1996 ATV XPRESS 300 CLUTCH COVER (400) XPRESS 400 W969540 (4935923592C008)
1996 ATV XPRESS 400 CLUTCH COVER (400) XPRESS 400 W969540 (4935923592C008)
1996 ATV TRAIL BLAZER ES CLUTCH COVER (SPORT) - W968540 (4935863586C007)
1996 ATV SPORT 400L CLUTCH COVER (SPORT) - W968540 (4935863586C007)
1996 ATV NORWEGIAN 400L 6X6 CLUTCH COVER 6X6 400L - W968740 and 6X6 400L Norwegian - N968740 (4935963596C009)
1996 ATV 400L 6X6 CLUTCH COVER 6X6 400L - W968740 and 6X6 400L Norwegian - N968740 (4935963596C009)
1996 ATV SCRAMBLER CLUTCH COVER Scrambler W967840 (4935823582C006)
1996 ATV SPORTSMAN 4X4 CLUTCH COVER Sportsman 4x4 W968040 (4935943594C007)

 

Thanks again for the help with part numbers. I've got pretty much all the parts I need sitting here now. Hopefully going to make some progress on it tomorrow. I do have a question though.

I just rebuilt the master cylinder. It's working great, builds pressure good, and I was able to bleed the left front brake. However, the right front brake and the rear brake don't seem to be getting any fluid. I can hold hard pressure on the brake handle and take the brake line for the right front caliper loose and nothing comes out. I think the rear is the same way. Any idea what's wrong? I may just pull the lines off and try to clean them out but I'm not sure if that's the issue or if it could be the splitter block or what? Thanks

 

May be in the block or individual lines. That's where a compressor and a blow gun can come in handy clearing any blocked lines.I'd just remove the main brake line at the master cylinder and at the calipers then blow through the main line first and see if it opens everything up.If that doesn't help then reverse clean the lines. Hopefully you wont have to separate them at the splitter block.

 

Well I got the brake lines cleared. It took some wire and fishing to free up the gunk but all that seems good now. I got the new clutch backing plate installed, got the starter on, fixed the motor mounts, installed a new battery and reinstalled the clutches with a new Gates drive belt. Starter works good and engine runs good. I've gotten most all of the hard stuff done.

The problem is that it still doesn't accelerate like I think it should. If I nail it from a stop, the engine takes a second to come up to speed and then the clutch grabs and it pulls hard till about 10mph. Then it still accelerates but it's really slow after that first 10mph. Topped out as fast as it will go is about 25mph just guessing. I know this thing should run 40 surely. I took a short video of the clutches. They seem to go through their full range of motion in neutral. Do you see anything wrong here opt? It just feels to me like when you're riding it that the engine will rev hard but the clutches don't advance properly. That or someone changed sprockets??

https://m.youtube.com/watch?v=llm9xMbEjmE

 

First off I would have stayed with the oem Polaris belt,but doesn't sound like that's your problem. Sound more like the clutches need to be checked into,especially the rear clutch on non ebs systems. Worn ramp buttons along with worn guide buttons/plain bearings in the front clutch can slow down it's operation. Several videos on youtube on this. Here's one on rebuilding them front clutch. Plus the rear ramp buttons if really worn down can muck up things and not let the clutch engage properly. I've found many that looked like this.The manual can really help you out especially on replacing rear clutch buttons and preloading the spring. Or you can simply remove them and have them checked out/repaired at any shop.

 

Well its been a few days, but I have some updates. Both good and bad I guess.


So, I hadn't messed with the crank any after I got the engine mounts good and tight because I did my best to check it out before I ever ordered any parts. Unfortunately, the crank bearings are bad Go Crazy I think I couldn't tell it before because of how loose the engine was. Plus, with the clutch on, its harder to have a good visual on the crank moving.



The good news is that with the plastic off, it took me 50 minutes to get the engine out and on the ground. Pretty straight forward. I probably would have just re-sold this machine to someone as a project if I had known the crank needed bearings because Im going to wind up having $1000 or a little better in it by the time its said and done. You can buy a pretty decent one for that, however, this machine will have new starter, battery, brakes, rebuilt clutches, crank bearings and probably some other parts as well.


I have attached some images of what the piston and cylinder bore look like. The Rod bearings still feel good, and I think the plan as of now is to leave it. It may or may not be the thing to do and I may or may not change my mind, but I don't see a problem with them. As far as the piston, it has one decent scratch and maybe a couple smaller ones. The one you can hang your nail on pretty good. The bore still looks pretty nice. I think it could be honed and be fine. I was planning to hone it and throw on some new rings at the least. I guess im looking for your opinion on what to do with the cylinder/piston. I could do a hone/ring job only, I could do a new piston, rings, and hone, or I could do an oversize piston, rings, and bore. I don't think it needs boring and Im trying to keep costs down while still keeping this thing reliable. I know you've done many of them, so keeping cost in mind, what would be your recommendation?


I do have all the crank bearings off the crank, as well as the oil pump gear. The new bearings are sitting here waiting to go on, so I can basically stick the bottom end back together whenever I get the motivation. Smile


Thanks for your help!

 

Crank bearings out and seal moving around with them causing lean running condition.Piston showing signs of wear along with the cylinder. Mic the piston to cyl clearance. If .004 or over order the next over size piston and rings,Wiseco being the best and have it bored and honed. Don't over look ANY up and down play on the lower rod bearing or a new top end would be useless as soon the rod bearing would take out the new top end.No sense in partially building an old engine and having that much into it when a rod kit is fairly cheap and most machine shops wouldn't charge that much to replace and true up the crankshaft.That is if you plan on keeping it after this ordeal. All 250 and 300 engines use the same rod.http://www.ebay.com/itm/1996-99-Polaris-P300-XPLORER-4X4-Bronco-Connecting-Rod-Kit-/231584043769?hash=item35eb7c12f9&vxp=mtr Good part about this if you do it up right and decide to keep it,it should give you years of service. Still cheaper than buying a new machine.

 

Ok Im back. Once again, ive gotten sidetracked from finishing this machine, but it will get done.


So now for my next question. Ive got the new crank bearings on the crank. I got the flywheel side in the case, everything felt good. Then I heated the clutch side of the case that the two bearings go into and got it down on that. Everything went well and seemed good. I have two shims between the crank and the first bearing on the clutch side, and one shim between the bearings on the clutch side, just as it came from the factory, and the same way all the parts diagrams show it to work. The problem is that when I tighten up the case bolts, the crank gets just tight enough that it takes a good bit of effort to spin it. I thought I was going to have the bottom end together tonight and then this little issue came up. The bearings all spin free on their own, so the issue here is clearance I guess. Have you ever had this problem OPT? Ive assembled several ATV engines now and never had an issue until this one. If you loosen the case bolts, everything spins free again. I thought about pulling one of the shims that space the bearing out from the crankshaft, but im not sure if that is the correct thing to do. Any ideas? I haven't done anything with the top end yet, but plan on an oversize piston. Thanks!

Eric

 

Just take a dead blow hammer and whack one end of the crank shaft after the case bolts are tightened. If it's still stiff to turn,whack the other side of the crank shaft. This is a common thing as I've had to do that on practically ever engine I've rebuilt.Especially on ones that I've had to replace rods on also.The rod will still be a little stiff to turn but will break in fine. If you didn't replace the rod and IF there's any doubt on the lower rod bearing there's still time to replace it.. Nothing worse than just replacing crank bearings and a new top end and then having a rod bearing go out later.. Also if you have the plastic oil pump drive gear it needs to be replaced with the metal one.. The plastic one could get hot and melt and fail.. Item #20.http://www.cyclepartswarehouse.com/f...1994&fveh=5381