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postie bike massive oil leak

Discussion in 'Technical and Troubleshooting Torque' started by skinny jim, Apr 25, 2015.

  1. hello.

    i have a ct110 which has an oil leak. it had some electrical issues when i bought it a few months ago (hence i got it cheap) which i managed to sort out . it was running strong for a month or so then it developed a big oil leak. i took off the bash plate and tracked the oil leak down to the outlet on top of the crank case, which has a drain hose that runs down under the carby. it sort of looks like a pcv valve outlet, maybe? if i can figure out how to post a picture, i will do so.

    once the bike is started, after 20 seconds or so this hose will start a steady flow of oil. i've managed to drain the oil out of the engine two or three times during this process of tracking down the leak, and luckilly i haven't seized it yet.was

    i've had a look at a another ct110 and confirmed that this hose is a drain hose and hasn't come loose from somewhere that it supposed to be connected to.

    so i'm wondering why this hose has suddenly decided to dump all the oil out of the engine. is it a sympton of a blocked oil filter, for example? or a faulty pcv? i'm at a loss. please help, internerds.
  2. Normally if u have oil coming out of the crankcase breather it's a sign your piston rings are very worn and compression is getting into the sump. It may also be due to having too much oil in the motor
  3. Is there enough back pressure to stall the engine? How petrolly is the oil?

    If the oil is quite petrolly you have a fuel leak, I would suspect an o ring on the jets. If not, do a compression test. If it's rings, I wouldn't bother trying to fix it, a new engine is only 300 or so.
  4. ah crap. i feared it might be a bit serious. bugger. the oil doesn't seem too petrolly but i'll double check that. thanks for the responses, it gives me something to work with..
  5. It's not too much of an issue like I said. While you can put up with it, just get the cheapest oil you can from coles or woolies and keep topping it up. When you want to fix it, a new engine is cheaper to buy than a service and and a bit of extra labour on a normal bike.
  6. Hey guys I just wanted to update this and thank you guys for your assistance. It turned out to be the piston / rings as suspected. The cam chain and tensioner was also shagged. Did a compression test and it was low, and a lot of compression was getting into the crank case. Hence the oil spraying out of the vent.

    Leaving it as is wasn't really an option as I was spraying oil all over the place every time I rode the bike, and the building manager in my apartment building followed the trail of oil back to my bike and let me know that he wasn't too happy about it , lol.

    I picked up a new piston / cylinder kit from ebay for less than it would've cost to get the old cylinder honed etc. About $140. My local bike shop Kustom Kommune installed it and the bike is running great again.