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18 SBA 800 (Engine) Longevity?

8K views 24 replies 12 participants last post by  NavyNut 
#1 ·
My 18 SBA 800 144” now sits at around 6980kms (approx 4365 miles) and at what point should I consider doing a rebuild if even needing to do one at all?

I’ve read from other sources some if not most people are rebuilding at approx 8000-12500kms (5000-8000 miles)
 
#2 ·
Do a quick compression test and youll have your answer..... Change out
your fuel sock or filter at the end of the year. Read your manual on what
mileage to change out the filter. The 800 motor for your year of sled is good.
way to early for a rebuild. Put in 4-6 ounces of the snowmobile oil of your
choice and mix it with a gas container and put it in your tank on every
fill up. Keep an eye on the temperature of your sled dont let it get over
180 degrees, if it does shut the motor down and let it cool off.
Keep the oil topped up, dont overheat the engine, add oil to your fuel
this sled will run past 14,000 miles with no rebuild.... Run a compression
test at the end of the year if unsure of engine reliability
 
#3 · (Edited)
Do a quick compression test and youll have your answer..... Change out
your fuel sock or filter at the end of the year. Read your manual on what
mileage to change out the filter. The 800 motor for your year of sled is good.
way to early for a rebuild. Put in 4-6 ounces of the snowmobile oil of your
choice and mix it with a gas container and put it in your tank on every
fill up. Keep an eye on the temperature of your sled dont let it get over
180 degrees, if it does shut the motor down and let it cool off.
Keep the oil topped up, dont overheat the engine, add oil to your fuel
this sled will run past 14,000 miles with no rebuild.... Run a compression
test at the end of the year if unsure of engine reliability
I’ve never done a compression test on anything before but I know that princess auto sells the kits for it and I’m sure with a little YouTube mechanic video I can figure it out quite easily. What are ideal compression pressures? Also what is the benefit of the oil directly in the gas, lubrication?
 
#5 ·
I’ll offer this. There is no trophy for who squeezes the most miles out of thier engines. So I never subscribe to the idea of running them past 5000 miles. I would not personally even run my engines that long. But my father in his 70s is east on them so I would say he could go 5000. It’s my opinion. That you take them apart on your terms not on the sleds terms. If the sled decides it’s generally way more expensive and catastrophic.
 
#6 ·
Compression 125 range, 10 percent difference between each cylinder is okay
for a reading. Oil in gas, lubricates injectors, fuel pump, and it benefits the engine,
a mixed, oil and fuel spray. A mechanic on this site serviced 2 polaris 2012
rush pro rr 800,s with over 14,000 miles, compression still good,
and injectors were fine..... no rebuilt motors and put 4-5 ounces of oil in the
fuel on each fillup. My source this site, use the search community feature.....
 
#11 ·
Engine rotating assembly? As in the crank you mean? The 800ho is a dry crank(sealed bearings) and doesn’t have a lot of oil in there in the first place.

As for the other questions premixing your oil through the fuel tank allows extra lubrication on/around your transfer ports, better skirt wear and less piston slap=more miles out of your pistons. Biggest killer of these engines is heat and lube. The amount to premix is subjective, dumping in the tank before topping up is fine. But most people recommend on a motor that is broken in about 1oz per gallon(128:1) but like said it’s subjective and I’ve seen as little as 200:1 recommendation. It can also benefit your fuel pump, injectors and summer storage. Break-in procedures are a whole other ball game of premixing the first 1000mi. Klotz octane boost is great as well. One of the biggest failures seen on these motors is from the piston rocking from wear and excessive skirt wear, this cannot be found out with a compression test. Examine through the exhaust valves is best w/o disassembly. Another common failure(as mine did at 4000mi) is the loss of the ring locator pin, cause the ring to spin and catch a port. In my case it was a total loss and is currently under rebuild. Lots of reputable engine builders on here recommend these steps mentioned above, along with other extensive(compared to the past) steps to make with regard of PTCW clearance, honing finish, injector test/clean, etc when doing a top end. Keep that in mind if/when doing PM to your top end.

Because it’s difficult to tell if your pistons are worn enough for a top end(aside from compression test and inspection), there are other signs to look for. Loss of power/rpm compared to before is another indication, possibly even a leak-down test. If all these check out a lot of these reputable builders say to run it, a don’t fix what ain’t broke kinda thing. All my sources are also from this site and some others that these builders have multiple accounts on, I’ve recently been doing my own extensive research on the topic since mine went down last week and have learned a lot to improve on with my new engine when it’s done. Good luck.
 
#17 ·
Maybe. Well probably. But I dont know about it being enough to say so. But I have no data to prove otherwise. Im not sure they have any real data to prove how much is in there either beyond the therory of some could get it’s way back down there in less efficient areas of running. Idk. We can go round and round all night o how much fuel comes out of atomization on a sdi engine that pulses the injector right at a wall. Anyway if it does it’s by fault in design not by design I would bet. I’m not saying somebody should never put a drop of oil in the gas I’m just saying I’m not sold on it being night and day to longevity in these engines. We both know what is and the epa doesn’t like it. Lol
 
#20 ·
No drama at all bud. These engines are considered to be a dry crankcase that’s why they produce crankcase heat they don’t have the 20 degree fuel introduced to the bottom end to quench the heat. A lot of this diffusion comes from the evolution of some might say deevolution for asloects if the 2 stroke due to epa. Carbs that delivered fuel and oil mixed I tiduced bith to bottom end so oil in gas would introduce more , throttle body injection would Inteoduce oil in gas to bottom end if you added more to fuel , so clever we have been trained. to think that way. But an sdi Polaris does not intentionally introduce fuel or anything added to fuel into the bottom end. Polaris for part of beak in used to call for adding oil to fuel for first tank they even did this on the 800ho. In 15. They shortly thereafter stopped calling for oil in the gas tank . If it was measurably and consistently effective do we think they would discontinue this direction ? So what we are left with is a therory ,which might be true, that some fuel in less effieciant areas of the running make there way down in the engine as air is moving up and gets to the bottom end. It’s possible but how much is it really ? I think it’s very small amount super small even but with that being said if I thought I was having an oil issue out on the trail I would probably put some oil in the gas hoping it would help get me home.
 
#21 ·
I completely agree, not much data out their supporting the argument at all, mostly theories albeit good ones. And for the owners who’s engines that do last say 8000mi without an issue that premix that extra 4-6ounces, well I’m betting to argue there is an equal or almost equal amount of owners that don’t do squat but gas an go with similar mileage. There are so many units out there, and most of the time you only hear of the bad ones especially on these forums and in shops. I dare say this but the crankcase heat with Polaris SDI engines is true as well, and I guess that’s one area that Rotax definitely got it right with the Etec.
 
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