F7 leaking oil vent tube

Discussion in '2 smokers' started by sjc56, Jun 3, 2013.

  1. sjc56

    sjc56 Long timer

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    I have oil dripping out of the oil tank vent tube when trying to kick over. Bike started doing this after i rebuilt the carburetor and replaced the clutch, which involves removing the oil pump. I did an 80 mile ride, bike ran so so bogged down didn't want to start after a lunch stop. I tried to start it Saturday, no go and a puddle of 2 stroke oil under the bike after kicking it over many times. Tank is not over filled, it did do this before my ride and bike does smoke at higher rpm's.
    #1
  2. bogieboy

    bogieboy Long timer

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    hmm my first guesswould be that the carb rebuild may have jetted the carb too lean? not sure on the oil overflow, as my f11 ( the 250) hasnt had a working oil pump the entire time i have had it....i just run 32:1 premix....
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  3. sjc56

    sjc56 Long timer

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    Stock jetting on the carb, seems like I am getting to much oil. It started last night with one Kick and smoked big time killed some bugs though. When checking the pump(it's disconnected when checking) my Haynes says 20-1 but I have heard with the new oils you can run less.
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  4. bogieboy

    bogieboy Long timer

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    Yeah 20-1 is just to be on the safe side.....which ironically will make the engine run lean, due to more oil and less gas, but more lube in the lean condition somewhat helps that....LOL
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  5. sjc56

    sjc56 Long timer

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    We just have gas with 10% ethanol around here which also helps leans things out, though my plugs show I'm running rich or to much oil, dark no soot.
    #5
  6. joexr

    joexr Banned

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    Is the air filter clean?
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  7. sjc56

    sjc56 Long timer

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    Yes
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  8. bogieboy

    bogieboy Long timer

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    as for the not running portion, i would check to make sure you have a good fat blue spark and if not, clean out your points, and possibly try a new plug, that helped me get my f11 running again...

    as for the oil drip, not really sure what that could be other thana loose fitting somewhere... can you trace the oil to where the leak originates?
    #8
  9. sjc56

    sjc56 Long timer

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    Well the drip is from the oil tank vent hose, no points so they are fine good spark new plug. Oh and it did start one kick the other day.
    I have been doing the timing belt, water pump ,seals on my Subaru so haven't any time for the F7 this week.
    #9
  10. Dabears

    Dabears Long Timer

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    Have you verified that the rubber flange between the carb and the engine case is sealing tight? They shrink over time and with no clamp involved will be first logical place for an air gap.

    Otherwise crank seals could be a concern too.

    FYI, I sold my F7 a couple years ago...
    #10
  11. bogieboy

    bogieboy Long timer

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    I thought about that boot, but the plug seems to read rich from my understanding, which would eliminate an air leak from my list of concerns....
    #11
  12. Duck_Pilot

    Duck_Pilot Retired Roadracer

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    Take a good look at your transmission case oil. If it looks fouled, or is low, you may well have a crank seal problem on that side. Lost crankcase compression can pump tranny oil out the vents, while intake vacuum can draw that extra oil in for combustion. If a 2-T engine has been sitting a long time before being run again, I am always cautious about crank seals. Might be worth a look-see.
    #12
  13. cgk64

    cgk64 Adventurer

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    I have to change the clutch on my 71 f-7, how much work is involved.
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  14. bogieboy

    bogieboy Long timer

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    if its similar to my ke100 (i think it is, both are rotary inducted kawasakis) it wasnt too difficult...bull the carb and oil pump covers, drain the trans, then pull the side case off, clutch is right there, 6 bolts for the pressure plate and springs, pull the friction disks and replace making sure to alternate, staring and ending with a friction disk,and having a steel disk between each friction...then bolt up the pressure plate and springs, throw the covers on, filler up and reset the clutch cable.... i did my ke in about an hr and a half, but i have done more than one clutch, did a honda 110, a F11, and now the ke... its not too difficult...if you are unsure of how to get everything apart, grab a Clymers manual, or a factory service manual, they will lay out the process step by step, and show good illustrations of what needs to be done.
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  15. bogieboy

    bogieboy Long timer

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    good question...given the not running right, and the pressure, i think the right side crank seal may be the culprit, that would show rich on the plug due to the extra oil, and cause the blowby to the tank...
    #15
  16. sjc56

    sjc56 Long timer

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    Can you replace the crank seal externally or do you have to disassemble the motor to get there?
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  17. sjc56

    sjc56 Long timer

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  18. ABee

    ABee Near Normal

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    The only thing that can be pressurizing your external oil tank is the oil pump itself. This means you probably got the oil lines backward when you put the oil pump back on the bike. Your pump is now pushing air into your oil tank rather than pulling oil into the engine, this is causing the leak out the tank vent. Get out your manual, make sure the oil lines are correctly installed, and you should be back in business.
    #18
  19. sjc56

    sjc56 Long timer

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    Thanks I'll check, but I did do an 80 mile ride with out killing the motor.
    #19