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Discussion Starter #1
Picked up a disassembled Polaris Xplorer 300, engine was completely torn down by the PO and I'm going to start on it today after work. Its a 2-stroke engine with oil injection. Since it doesn't have a cam or any valves, I'd imagine the piston is directional to allow the piston skirts to line up properly with the intake and exhaust, correct? Any tips on what to look for? I bought a service manual; but it does not specify. TIA:beerchug:
 

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Sounds like FUN!
 

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Discussion Starter #5
Alright, that makes it easy enough.

Now a question I'm ashamed to ask; but be easy on me as I've only ever rebuilt car/truck engines. This is my first 2-stroke project. What kind of lubrication does the crank case take? The manual lists engine oil for the 4 stroke engines; but says nothing about lube for the 2 stroke crankcase. There's bearings down there... that tells me there must be fluid! Funny how an engine way less complex than what I'm used to dealing with is making me feel like a complete novice.:wow:
 

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The oil from the injection pump will lube the bottom end. use a good synthetic oil not the Polaris stuff. Make sure you lube all bearings lightly on reassembly and use 1104 Three Bond to seal the crankcase. Make sure to break loose the bleeder screw on the oil pump and bleed out any air in the system. Good luck!
 

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2 stroke pistons have an arrow on the top of the piston, the arrow always points to the exhaust side, or forward, the oil pump provides the mix for the 2 stroke, if the pump is being bypassed, mix the gas at a 32:1 ratio, i had to do this with my old 87 cyclone
hth
Rick, Ore
 

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Yes what you say is true to some point but it depends on the manufacture what way the arrow points so do not use that as a guide. The 32.1 mix will work on the first tank then switch to 40.1 or just run Amsoil 100.1 premix this is real good stuff. Yes you can mix it at 100.1 as we have mixed at 180.1 in drag sleds with over 300 hp with no failures.
 

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Discussion Starter #9
Finally got a start on this over the weekend. With the arrow on the piston pointing toward the exhaust side, the "pins" for the piston rings are facing towards the intake side; so I assume that's a good sign. Got old bearings and seals replaced with new, put the new crank in, and mated the two halves of the crankcase. Couldn't get any further than that as one of the piston wrist pin retaining clips is missing.

I guess I still don't completely understand (or maybe trust) how the bottom-end stays lubed if the crankcase isn't filled up with 2cycle by the oil pump. It makes sense for the bearing on the flywheel end near the pump; but the bearings on the other end of the crank and the little needle bearings on the piston wrist pin are a good distance away from there. I did put a light coat of oil on everything while assembling.

Oh, and BTW, when I cleaned up the crank case, it had 241cc and the mfgr name machined into it. I could justify calling a 241cc motor a 250... but Polaris is pretty ambitious passing it off as a 300. LOL
 

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The bottom end will be fine. The crank and case for the 250 and 300 are the same that is why they have the 241cc stamped on it. The top end is what is different.
 

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Discussion Starter #11
Okay, got a new wrist pin retaining clip from the dealer; so progress could resume. I have the entire engine itself assembled now and it turns smoothly with a 22mm wrench on the flywheel bolt. Really, I expect the engine to be the easy part, its just a few major components. Figuring out where the rest of the Folgers can's offerings go will be the tricky part.:kopfkratz: I printed the parts manual from Polaris' website; so the exploded views really help work through things. Definitely recommend that to anyone doing a similar project.
 

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If you have any problems just send me pictures of the machine and what you have for bolts and I can probably tell where they need to go. Good Luck!
 

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Discussion Starter #13
Great! I'll just lay them all on a tarp and take a picture so you can label them.

































































































j/k :nana: But I do appreciate the help!
 

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Discussion Starter #15
Got more done tonight. Flywheel and pull-start mechanism installed and body mount brackets bolted on. Here's the engine not far from its home:




Not bad considering this is the ATV as I bought it:




And the engine/clutches/plastics/etc were stripped down and stirred together in here:




I started visually tracing the fuel and electric lines and it doesn't look like its going to be as brutal as I had feared... especially with the parts manual to go by.
 

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Discussion Starter #16
1998 Xplorer 300 4x4

A few parts from the Folger's can I'm not 100% about:




I think the lower black plastic disk is a damper for the upper body mount. There was only one of them and the parts manual only shows one, located at that mount. It also matches that location in terms of ID and OD.

The upper metal washer fell off when I was pushing the ATV into the barn... just not sure from where. Its roughly 1 3/8" OD and 7/8" ID.

The other piece appears to be a standard square head pipe plug. I see nowhere on the engine or tranny that would utilize it as a drain plug; so I'm not even sure it belongs to the ATV??? It WAS in the Folger's can, though. :suspect: LOL
 

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You are correct the plastic piece would be for the front struts. The washer is a 0.60 thousands shim that goes on the tranny out put shaft to make sure the clutches are aligned properly. Keep in mind you need at least one of them on the shaft and sometimes as many as three. The plug does not look like a drain or filler plug that I have ever seen. To make sure somebody did not rig something up check the tranny and front and rear diffs.
 

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Discussion Starter #18
The washer is a 0.60 thousands shim that goes on the tranny out put shaft to make sure the clutches are aligned properly.

So in the below picture, it would go on the rusty shaft (to right of the engine in pic) BEFORE the driven clutch goes on? That would be the input shaft by my understanding; but what I would call the output shaft (that drives the chain) was never taken apart so it can't go there. Or did you mean the engine output shaft before the drive clutch goes on? Thanks again for the help!


 

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You are correct the shim goes on the rusty tranny out put shaft. I would use a scothbrite pad to clean up that shaft then put a very little grease only on the splines of the shaft. You do not want any grease flinging around on the clutches.
 

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Discussion Starter #20
You are correct the shim goes on the rusty tranny out put shaft.
And correct that the spacer goes on BEFORE the driven clutch? I only found that one spacer... but I drove 70 miles with the ATV on a trailer between the original owner's house and my own; so others could have been lost in transit. And don't worry, I definitely intend to take care of that rust!
 
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