I need to do a complete rebuild on a '95 Polaris 300 4X4 2-stroke engine. This engine had the plastic oil pump gear. It ate the plastic gear and the top end seized up. Bottom end has a lot of runout on the clutch end (.015") and main bearings sound rough. As an option, I am considering a used bottom end or even a used motor. I need help determining which 300cc engines are compatible with the '95. I thought I could go by the crankcase part numbers, but this model is so old, most online dealers don't list the P/N for the engine cases. I know that it is a EC28PF01 model engine. Just moving to a '97 model, the engine model# changes to EC28PFE01. Any help would be appreciated.

 

All are compatible just minor changes in engine numbers because of increased stator output,jetting,etc. Confusing,but you can order parts from your model and all newer parts such as this plastic oil pump gear will be updated to steel. Yea I know about the plastic oil pump gear on the first year model 300. Couldn't believe the first one I tore apart that was chewed up. The replacement I ordered was already updated to the metal one. Polaris tried to go cheap and it bit em.I wouldn't trust ANY used bottom end. Better to rebuild the one you have.As mentioned all parts that are in the newer models have been updated on yours. Look at #16 and the updated part number.Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse

 

Thanks for your response. I am finally completing the rebuild. I have run into another snag. The engine mounting bracket was broken at the back of the cylinder. The temp switch was damaged. Polaris no longer sells P/N 4010211. I followed the Explorer 300 model up to 2000 and found that Polaris sells P/N 4010284, which has the same description. I am sure something is different, but what? How would you handle this?

 

Hopefully answered this in your other post..

 

I am replying to this post in hopes someone else might benefit from it. The Temperature switch P/N 4010211 is exactly the same as the 4010284. Polaris was absolutly no help figuring this out. They say it won't work and just tell you the part is obsolete.

 

Problem is with all these sensors on the 300 is that they break from vibration being mounted on the rear engine bracket which is not an accurate way to measure engine temperature for the fan to kick on. Plus most are set to kick on at 235 degrees and kick off at 210 degrees which is really stupid. For the most part I hardly ever heard one kick on. Actually better if you want the fan option on this air cooled engine to take the two sensor wires and wire them to a toggle switch that you can turn on while under a load or driving slow for long periods of time. Many air cooled 2 and 4 stroke engines never even had fans including the Polaris 250 engine.