Hi All,
I purchased a 1987 Trail boss 250 a couple of years ago from a guy who pretty much rebuilt it including a full engine rebuild. Currently, I and am in the process of cleaning up some of the things he hacked such as wrong brake calipers, cable ties for hose clamps, etc.

And although I've never had a problem with the oil injection I would prefer to use premix and was considering removing the oil injection system completely and blocking it off.

My thought was to premix 40 to 1 with quality 2 cycle oil and never worry about the injection system again.

Any reason not to do this?
Any suggestions on where to get a block off kit?

Thanks

 

You don't have to remove the pump,just drain the tank,remove the line at the base of the cylinder and cap it off. If you remove the pump you still have that spit cable that doesn't always work well just pulling the carb slide only. If you're determined to remove the pump,you can get a block off kit here plus they have single throttle cables if you wish.Aaen Performance - Polaris ATV Two Stroke - Top End Pipes Tight fit with the engine in the frame,but can be done like in this video.

 

Hmmmm, I like your idea better. Just leave the pump, cap the line, and get a single cable throttle. Easier and cheaper.

Thanks again OPT!

 

You don't have to get a single cable. Just leave the original cable hooked to the pump arm. Pull the small hose from the pump to the cylinder and use a small rubber cap on the cylinder injector to keep it from sucking air.

 

I once owned a 400 Sportsman that the previous owner unhooked the oil injection and ran premix. It smoked and fouled the plug if you let it idle. I hooked it back up, ran the Polaris Blue injection oil and measured the exact amount of gas it used on a trip and the amount of injection oil, just to verify that it was injecting the correct amount. It was about 65/1 ratio. Once I ran the premix out, it ran better and no smoke, just saying, if it's not broke, but if you want to verify, you can measure the amount used.

 

65/1 no wonder it didn't smoke that much.. If the pump arm mark on the 250/300 and the mark on the wheel on the 400 are adjusted to where they align with the mark on the variable pump body at an idle,oil is then metered at a constant 50/1 ratio.It doesn't give this ratio in the manuals but I had to question a couple of Polaris engineers to find that out.

 

Hey OPT,
I am taking your advice and leaving the pump, draining the tank, and capping off the oil injection intake on the engine. Also ordered a new dual throttle cable because my cable was kinked and would not release easily when revving. The dual cable was a lot cheaper than the single cable anyway.

My plan is to start with a mix at 40 to 1 and if all goes well go to 50 to 1 with a high quality (synthetic) 2 cycle oil.

Thanks again!!!

 

Premixing I'd stay at 40/1 with a good synthetic oil.Most people had no problems with that in over all riding conditions. In defense of the 250 oil pumps they were pretty near bullet proof. Only problem with the 300 engine was the early ones used a plastic drive gear.That was changed back to the same one the 250 used later on.The 350/400 oil pump was a different story. Not that this Mikuni pump was bad,just that it was located at the front of the atv and moisture could cause corrosion, rust and freeze the pump wheel.This pump was the one I really recommended to block off and premix or keep a close check on the pump condition.

 

Wow great info!

OK, I will stick with 40-1 using synthetic oil.

I also have a 1994 300 that runs like a dream. My wife loves to drive it. Maybe I should be running premix in that one too. Was the improved pump in place by 1994?

Thanks!

 

That's the model that some,not all, had a plastic oil pump drive gear...If it had the plastic gear it should have shown up by now I would think..