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Oil/fuel leak where exhaust meets the cylinder Predator 50 2 stroke

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Oil/fuel leak where exhaust meets the cylinder Predator 50 2 stroke

  #1  
Old 06-06-2019, 11:21 AM
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Default Oil/fuel leak where exhaust meets the cylinder Predator 50 2 stroke

Working on several different issues, but maybe they're all the same culprit. 04 predator 50 2 stroke. Hard starts, basically it starts when it wants to. Compression is not great (I vaguely remember it being 75-80 on the electric start, but will re test tonight). To me it acts like it's starving for fuel, so I may have several factors. If I drop a little pre-mix into the carb through the air intake, it fires right up, but drips a decent amount of oily gas onto the exhaust, which smokes when it warms up. I know there's a gasket where the exhaust bolts up, so that's the first thing to replace, but I also don't think that gasket looks like it would even stop a leak like that. Exhaust seems pretty oily back by the muffler too, although I recently stood it up on it's end and that probably made a bit of a mess.

My gut says if oil can leak out of there, so could air, which could explain low compression? I'm just a little baffled by the oil drip there. Carb has just been rebuilt, if that matters, oil leaked out before and after the carb rebuild.
 
  #2  
Old 06-06-2019, 11:40 AM
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If your compression is that low then its time for a upper end rebuild.. if memory serves me right compression should be double that... Back to your other post since now you know its a 2 stroke are u doing a oil fuel mix or are u using the machines oil injection? Its quite common for the oil pumps to fail so allot of people do not use them and just mix their own fuel/oil

FYI it would have ben easier to to just add to your other post
 
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Old 06-06-2019, 02:13 PM
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This one is still pumping oil, so for right now I am using the pump. I'm 100% sure it's pumping oil because some of it is running right out of the lower part of exhaust. I do plan on switching it over to pre-mix since my 06 is using premix, but I don't have a close source for ethanol free fuel yet, so it's a bit of a pain to gas these up with fresh fuel and I'd rather dump old fuel than old fuel + expensive Polaris Oil.

Any idea if rebuilding the top end will cure the leaky oil problem? I'm trying to picture how oil can be running straight through it without burning off with the gas. I've got the top end rebuild kit sitting at home already. I'm very much the type of person that if I can find instructions or take it apart, I can put it back together, but my engineering knowledge is not very heavily based in tearing down engines so it will be a learning thing for me.

Side note- I was worried adding to my other post wouldn't be good because this was a specific problem, and most people were probably just going to laugh at the title about checking non-existent valves anyway. I'd rather that post go away so I can focus on this problem. I should clarify that I knew this was a 2 stroke (I have 2 other late 90s polaris 2 strokes), I just did not know that there are no valves to adjust on the 2 stroke. The farthest I've ever been into one of these is replacing starters on the bigger Polaris quads, but like I said, if I can take it apart and I know torque specs etc, I can usually get it back together.
 
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Old 06-06-2019, 02:34 PM
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Possible it could be over oiling? Or running rich... if never had a issue with ethanol based fuel especially when mixed for my saws and such
 
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Old 06-07-2019, 01:44 AM
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I suspect the oil isn't being burnt because it isn't starting, so all the oil pumped into the sump, before it started, has to escape out of the exhaust. 80 psi is a bit low but I would have expected it to start. My guess is either the choke isn't working, or there is a carb problem, too much fuel or too little. Give it a good clean and check if the choke is OK (if possible). Check the exhaust isn't blocked, leaking out of the joint can be a sign of increased back pressure, though bikes usually start but won't rev if this is the problem.
 
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Old 06-07-2019, 08:13 AM
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You don't have enough compression (should be 90 minimum and good shape would be 130+) Thus the fuel isn't being burnt correctly (what merryman said). Altho I do think most all mini's have the same oil leak at the exhaust.
 
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Old 06-15-2019, 09:56 PM
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I also have 2stroke Predator. It ran but not well. I didnít leak oil or fuel but did have low compression. I replaced the top end, the jug, one of those 65$ kits off eBay and still low compression, but now wonít start. I know this isnít exactly help, but if you do go down the road of new jug, I wouldnít buy the cheaper ones....
 
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Old 06-16-2019, 02:37 AM
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Wouldn't call $65 cheap, as that "Minarelli" engine is made in Taiwan and China so manufacturers price won't be that expensive. Polaris may stick a huge markup on parts if you buy from them. I paid £25 for a piston & cylinder kit for a Honda 70, now that is cheap, and it worked!
 
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Old 06-16-2019, 07:51 AM
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I've replaced my last china cheapo cylinder. Absolute junk!
 
  #10  
Old 06-17-2019, 01:23 AM
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Just pointing out those Polaris two stroke engines came from Taiwan or China so wherever you buy parts, they will be made in either Taiwan or China.
 
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