Carb Problem or serious problem?

Discussion in 'The Workshop' started by Ryanthespeedshiteowner, May 8, 2017.

  1. Ryanthespeedshiteowner

    Ryanthespeedshiteowner New Member

    Messages:
    13
    hi I have got a speedfight 100cc and I have noticed I can not tune the air/fuel mixture, so the top speed is only 30 mph! and it bogs out after that. Is this a carb problem like jetting or something else? it has got a 100 jet in the carb atm also I have noticed it sprays a lot of fuel out of the air intake I have to have the air/fuel mixture screw turned all the way in if not it will bog even worse but when I give it gas on its stand with no weight on the bike it seems perfect does not stutter or bog. :mad: any help will be appreciated thanks - Ryan :cool:

    Ps the bike has got a K & N air filter on and have also tried standard air box but still no difference
     
  2. Tamiyacowboy

    Tamiyacowboy Pippa's Owner

    Messages:
    1,850
    Rides:
    Piaggio Skipper
    carb needs a strip down, could be the jets have blocked up and you need to give them a good blow through.

    remove main jet and pilot jet, then use some compressed air in a can and blow that into the port holes to help remove any objects that could have built up. now flip the carb so your looking at where the airbox fits onto, see those three / four little holes in the outer ring portion , again spray compressed air down them to get any junk out.

    fit the main jet and pilot jet back in and rebuild back up...... check the carb mounting points on engine and airbox for leaks , ie split rubbers , missing gaskets etc etc.

    ALSO please wear safety glasses when blowing out carbs, you do not want that dirt and petrol getting in your eyes.
     
  3. Ryanthespeedshiteowner

    Ryanthespeedshiteowner New Member

    Messages:
    13
    hi thanks for your reply.... I have already striped down the carb god knows how many times with compressed air and checked for air leaks my carb bolts on with a rubber mount is it possible that I've got to big of a main jet as I think the standard is a 85 and I have a 100 don't know if that would make me not able to tune the air/fuel mixture looking forward to your reply ps I have not got the original auto choke on the carb and the fitting is really lose I have sealed up the choke port with gasket seal before and it did not make much difference
     
  4. Tamiyacowboy

    Tamiyacowboy Pippa's Owner

    Messages:
    1,850
    Rides:
    Piaggio Skipper
    you maybe better finding a cheap replacement carb or grab an autochoke and fit that.

    its possible your overfueling with a to larger main jet, only way to see if dropping down to an 85 and see if that helps , usually a huge upjet would show as poor throttle / flooding and possible airbox spitting so you could be way overjetted.

    its kind of hard to tell without having a hands on look. but a rejet and a autochoke would be the better starting area , to be honest the K&N aint going to be doing any help either , ok on something like a big huge bike but a lil ol scooter not so good. if your going to fit that type of filtering system i would say your better going with a dual foam type, where they have an inner foam then an outer foam , a lot better but still going to be a pain in wet weather running.
     
  5. Ryanthespeedshiteowner

    Ryanthespeedshiteowner New Member

    Messages:
    13
    thank you for your info I have ordered a new carb off ebay with a 87 jet to see if that helps I will keep you posted
     
  6. scubabiker

    scubabiker NITROJUNKIE

    Messages:
    7,321
    for what its worth, the mixture screw really only affects idle speed mixture plus a little bit more, main jet is for full throttle mixture....
     
  7. Ryanthespeedshiteowner

    Ryanthespeedshiteowner New Member

    Messages:
    13
    I have solved this problem and it was quite obvious lol it was the carb and wiring because i was using the 50cc wiring loom and coil stator etc the spark was weak also float hight was not right now does 65 mph quite easy should go faster aswell with a little bit more work :)
     

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