Rob/Sub 35cc carburetor air filter soaked

Discussion in '4-Stroke Engines' started by Mountainman, Jul 25, 2008.

  1. Mountainman

    Mountainman Active Member

    The little Robin has been running well for the first 5 or 6 hundred miles -- until today I noticed some loss of power. The air filter is soaked with gas ? I cleanned it and put it back in -- getting wet fast. Any ideas ? Happy Riding from - Mountainman

  2. Happy Valley

    Happy Valley Active Member

    Any luck figuring out what the problem is MM?
  3. Unhappy Time

    Unhappy Time New Member

    On my scooter that happens when my air filter is not letting enough air through and it pulls more gas to equalize the vacuum. Then the wet filter makes the filter even less porous and starts a vicious cycle. Also it gets wet when my carb is adjusted too rich.
    Last edited: Jul 28, 2008
  4. mark2yahu

    mark2yahu Member

    Mountainman, it's probably clogged with dirt. You washed it, but I think there's dirt firmly embedded in the foam filter's pores. The filter is just made of black foam, the same as some packaging foam I've come across. You might want to try on a new filter. Keep us updated.
  5. Mountainman

    Mountainman Active Member

    well you all -- the beast was running pretty good at the end of today.. Started out this morning wondering what to expect - started as always - one or two licks - rode for a little while - I was trying to figure out why my engine seemed to be a slight bit sluggish - then took a short break and when it came to restart - A FIRST - WOULDN'T START !! Took about 12 cranks - then it fired up - idling somewhat rough - I took off and it was running poorly - and then it just broke loose and ran super fine - for the rest of the day ??? What was it ? I am just not sure - something in the carb or gas line that broke through ? A piece of carbon hanging something up ? A sticky valve ? I had my buddy follow me in his car - he said that I was going 22.5 mph - that's as good as it gets. It's always nice when things fix themselfs - but - leaves one wondering if and when it will happen again ? For now - Happy Riding from - Mountainman
    Last edited: Jul 28, 2008
  6. mark2yahu

    mark2yahu Member

    Some gunk built up, probably in the carb or fuel line as you said. I wonder if some of that fuel injector cleaner is okay to use in these little engines?
  7. ibdennyak

    ibdennyak Guest

    seafoam seems to work for me
  8. Mountainman

    Mountainman Active Member

    Hey you guys - I have heard a lot about sea foam on this site - new to me. The fuel line going to my carb - is VERY light weight - almost rubber looking. I wonder - Sea Foam maybe ? I would like to run some cleanner - if it won't melt it ! Off the subject - Man am I going to miss my MB - off to Kona today with the little Lady.. It would be a blast to have it with me - but - with the BIG mountains over there I would need a 1/2" roller on my friction -- I know - not even made.. Until we return - be safe and Happy Riding from - Mountainman
  9. mark2yahu

    mark2yahu Member

    I use Seafoam for storing small amounts of gas. Also Sta-Bil. When you use Seafoam, you might see some dark smoke, not a lot. Both will clean the fuel lines and keep the gas from turning to varnish. Still don't know about fuel injector cleaner. Have fun at Kona :)
  10. Wet filter

    Hi I don't know what you will find but as an old-time mechanic I can tell you thsat if your intake valve is too tight, it will "sneeze" fuel back into the air cleaner, and can, intermittently run really carpy, have you loosened your valves a bit?

  11. Mountainman

    Mountainman Active Member


    hey Mike -- sorry about the slow responce time here
    I haven't seen this thread for some time now

    no I haven't checked the valves
    that's someTHING I should do
    thank you

    ride that thing
  12. Mountainman

    Mountainman Active Member

    later down the road -- slight miss -- sea foam

    new no more -- more time down the road now
    the little Robin got just a slight bit slugglish -- down 2-3 mph
    bought the sea foam
    THINGS have picked back up to speed so it seems
    ran through two or three tanks of gas -- mixed pretty rich with sea foam

    today it sounded like a hoped up fine running high speed sewing machine !!!

    ride that THING
  13. WU7X

    WU7X New Member

    gassy air filter, etc.

    Hi guys!

    It's been a year since you started talking about your problems with gas in air filter. I was having some problems with my R/S engine too. It starts up pretty easily but then stutters a bit when running full out. It still does over 25 mph using the lower GEBE gearing and on a mountain bike, so I'm happy with that.

    From my use of other air filters associated with different applications, I'm guessing that some of that oil is that to catch minute dirt particles and came that way from the factory. K&N oil filters work that way.

    I took off the covers and noticed that the filters are/were covered in oil and had the smell of gasoline on the dark filter. I am not sure why I have the gassy smell though. So I just cleaned the darker air filter with soap and water and have dried it with paper towels. I used paper towels to suck up as much of the oil off the white filter element as I could get by applying a rolling pressure over the filter between several sheets of paper toweling. Will then reinstall it and see what happens. Oh, I also pulled the sparkplug. It was covered with a gray ash, not oily or dry, so think it should be o.k.

    I am going to add some Seafoam to the gas tank and try running the engine that way and see if I can emulate your results. This is my second summer with the engine on my bike and I only have just under 300 miles on it it so far. So thanks for the ideas on this thread. I'll let you know what I find out.

  14. Old Bob

    Old Bob Member

    The gassy smell is caused by spit back from carb. nothing you can do about it. just clean foam
  15. Oil in the air filter is a problem on Robins. Once the filter gets badly oiled it restricts air somewhat and that can cause a too rich mixture to wet the filter with gas. It comes from overfilling the crankcase. Subaru calls for 100 ccs of oil, but it is excess and gets sucked into the intake. Put in about 1/3 cup of very good oil, or fill to no more than 1/2 full on the dipstick. I prefer Castrol Syntec 5W-50 oil. It's expensive but we use such a small amount per oil change a quart lasts quite a while. Some even fill to no more than the lowest mark on the dipstick with no bad result. Clean both the white fiber and foam air filter elements with a good dish soap(I use Dawn), rinse well, and let them dry completely before reinstalling.
  16. Mountainman

    Mountainman Active Member

    I have been putting way too much oil in my Robin
    sometimes more is just not better

    got to love that Dawn stuff
    saved many birds in the oil spills

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