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Discussion Starter #1
Greets, I've had this atv for 1.5 yrs and now it's burning oil about a quart a month. I can't seem to find any resource online. Not familiar with the rotax engines. Any leads I can pursue? Runs great otherwise.

Thanks
 

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2015 Outlander XMR 650
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Welcome to the site, Rummy.

Easy answer would be to just chalk the oil burning up to age/hours on the engine, and the piston rings/cylinder wall relationship deteriorating over time, leading to oil getting by the scraper rings, and being sent out of the exhaust.

There's not a lot of online info out there on those older bikes, but if you search around this site, there are a couple/few guys sharing some of their experiences
 

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Start with checking compression and preferably leakdown, there is likely a problem doing so. These motors appear to have a automatic decompression system that is based on rpm's. What this means is at too low a rpm (say starter or not running speed) the exhaust valve is likely being held open to help the motor spin over. This will give you a false low reading on both unfortunately but would be worth. A leakdown test works by filling the cylinder at top dead center compression and measuring how much air leaks out as well as where it leaks out, if it is a worn cylinder or bad rings you would hear air in the crankcase. With a decompression mechanism you will have much leak out the exhaust valve .

I would try a compression test and then squirt a bit of oil in the cylinder seeing it it improves a lot, if it does you MAY have something going on there.

1 qt a month seems excessive how many miles is that? what rpms?

The cylinder is nikasil and good quality so unless you simply got a bad (soft) cylinder then it should outlast many other parts. Bad or no air filters will allow dirt to damage the piston and cylinder so if you run a poor air filter and ride in the dirt expect some scoring. The piston is nothing special just a cast piece but I see no reason it should wear too soon as there is lots of skirt to keep it stable. Rings are probably decent as well but this may be a wear area to look at .

If you pull the cylinder you may find everything in spec but the cylinder glazed (looking like little to no cross hatch), this can be fixed. If this is the case the cylinder can be deglazed and return valve seal. cylinders can get glazed from the cylinder being filled with fuel or a oil treatment, removing the glaze BUT NOT THE NIKASIL can fix this. Special hones need to be used so not to damage the nikasil but it should not be expensive to have done.
 

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Discussion Starter #4
thank you both for replies, I am not familiar with Rotax engine and how it works. ATV is used on farm, few times a day. Last month it died and I pulled the spark plugs and they were both shot and replaced them and ran great. Other than that its been a great machine.
 

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Define shot?
You put them in a shotgun and fired them off or there was something visibly wrong with them?
hint, what was wrong with them?

plugs that are black and wet might be wet from a carb problem and this can be telling you the cylinder is likely glazed. At the point the plugs were "shot" may have been telling you what is causing the oil issue. If you are not familiar with engines you might want to get someone who is to take a look at the cylinder and piston as well as to the carb to make sure if it is glazed it does not happen again.
 

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I am not familiar with Rotax engine and how it works
It's not some NASA-grade moon rover motor, lol, so don't let it intimidate you. It's an internal combustion engine like most out there.

Duc- I'm wondering if the plugs fouling out led to weak or no-spark conditions, which would just let fuel wash down the cylinders, compounding the age/wear already there.

Rummy- you need to perform a leakdown test on the cylinders. If you're losing air past the rings, well that's probably also where your oil is going, albeit in the other direction
 

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Yes fouled plugs could lead to washing the cylinder down but thank god that is not a common issue or I would be busier than I am. most of the time I see glazed cylinders it is due to a stuck float filling the cylinder with fuel or a top end oil issue (like worn valve guides) allowing too much oil getting in the cylinder top end. Either way it will need the top end pulled, luckily this should be done in the chassis and for not a ton of money or parts. If the cylinder and piston are not worn or glazed you can at least see,measure or fix it.

I think I saw a number of heads and top end parts used on ebay for short money so if you do have a worn piston or cylinder you can likely get another used one for about $100 for the set. New they do not show available but given the low tech nature and good cylinder materials I would CAREFULLY buy a used piston with no worried. I would bet wiseco or some other piston manufacturers have piston circlips in the proper size.
 

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Discussion Starter #8
LOL sorry that wasn't a very technical term. Here's a pic. What parts would I need to pull the top end- a new gasket? It gets operated for short periods of time, I don't really beat on it too much working around the property.

101016
 

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Do you run it year round how hot and how cold?

From what I see the plugs are pretty black which means running rich for some reason, check for a mouse nest in the airbox first off and if that's all you are done. If not you may want to drop at least one jet size. someone may have jetted it for winter time cold say ice fishing. If you run it in the summer with winter jetting expect it to be rich.

Top end should be common hand tools though you need to be careful with re-installing the piston in the cylinder so you do not break a piston ring.
 

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Discussion Starter #10
I think it is running rich, not sure how to adjust that. Guy i bought it from put a high flow air filter on it but did not put different jet in. I can smell gas occasionally when it's running. I did clean the carb when i got it, had some boogers in there.
 

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Looking at those plugs, it sure appears it is/was.
 

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if it is running too rich that extra fuel may be your main issue. The air filter itself should not be the issue as most stock filters flow almost the same air. That said if you know the carb is rich you may need to rejet or adjust the fuel screw at least. you can do this by feel and experience but even someone like me that has done it as a pro for decades understands a gas analyzer makes the job much faster and more accurate. If you have a shop near you with a gas analyzer it should make a noticeable change.

Step one is to make sure you do not have something off you (or the previous owner) touched.
1. float height
2. fuel screw
3. correct jets - unless you have a jet kit NEVER buy any brand of jet that is not marked on the jet that it was made by Mikuni. each piece of brass will have the miluni symbol on it and if it does not you have created a larger problem than need be. Something marked "for" or "the same as" or "works with" or "just like" means you are buying the wrong parts.
4. before you go further make sure the carburetor actually says Mikuni on the side, there are cheap chinese knock offs that are NOT the same and require jetting. I see these as people see a $40 new carb as better than a used $200 carb and often they are not. They can be made to work but often need a bit of work to get them right. Unmarked jets are often a indication you have a fake.

Same for brand-X rebuild kits often they come with brass but often are not sized the same even if the numbers on the jets are the same. Kind of like you handing me your wallet and I had you back one that looks the same but has foreign currency in it, sort of the same but not really.
 

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Discussion Starter #13
thank you for the reply, I don't see Mikuni on the side. I did remove it and clean it when I got this atv about 1.5yr ago, took it apart carefully and cleaned the jets and it ran better after that. Also the choke cable seems to get caught in open position if I pull it all the way out. Can you help me ID the fuel mix screw so I can just back it off a bit?

101034


101035
 

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https://www.amazon.com/Carb-Bombardier-Traxter-Carburetor-PD33J/dp/B07PTP37NV

Looking at mine the Mikuni name is cast into the body just above the float bowl in your top photo. There is a diaphragm cover with 2 Phillips screws above the logo. If you look at the carb in the amazon link above it is a 90% chinese copy that has NO markings in the same location. If you pull your carb off another way to tell will be the throttle plate on the engine side will have a number and symbol on the plate as well. the symbol is the Mikuni mark and it looks like a small box with another marking inside the box.

The chinese amazon carb is a good looking copy I would in no way expect it to work the same out of the box.
 

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Discussion Starter #15
I can't see any markings, probably have a Chicom knockoff. Which is the fuel mix screw? Can I just back it off a bit? Thanks for your responses!

https://www.amazon.com/Carb-Bombardier-Traxter-Carburetor-PD33J/dp/B07PTP37NV

Looking at mine the Mikuni name is cast into the body just above the float bowl in your top photo. There is a diaphragm cover with 2 Phillips screws above the logo. If you look at the carb in the amazon link above it is a 90% chinese copy that has NO markings in the same location. If you pull your carb off another way to tell will be the throttle plate on the engine side will have a number and symbol on the plate as well. the symbol is the Mikuni mark and it looks like a small box with another marking inside the box.

The chinese amazon carb is a good looking copy I would in no way expect it to work the same out of the box.
 

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Fuel screw is on the bottom of the carburetor.
engine side under the spigot dead center with a brass flat blade screw going up.
fuel screws will lean it out as you screw the screw in and rich as you screw out.
They are a tapered needle and can be damaged if you seat them too hard so just be gentle feeling for fully seated.
 
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