What size of mainjet for sha type carb – catalog ??

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This topic contains 6 reacties, has 3 deelnemers, and was last updated by AA-T 6 years, 1 month geleden.

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  • #709738

    jacekniemiec
    Topic starter
    Berichten: 22

    Hey Friends,

     

    i have diffirent mopeds piaggio  vespas :

    3X bravo : ’78,’ 80, ’85     year of made

    1X grillo : ’90 year of made

    1X ciao :  ’76  year of made

    All of this have diffirent carburators SHA 12.7, 12.10., 12.12. and 13.7

     

    All main jets are mixed up in thise carburators so only 3 of the mopeds are working. With tons of work and plenty of time of trying diffirent jets to de carbs I made Grillo and two bravos working but I am not super happy of how the engines works due to teh jets not properly combined to the type of SHA. My question is – is enybody have somything like catalog what type carb to what number of engine and to what type carb what size main jet ?

    All my fingernails are eated, half of the rest of my hair pulled off of the stress of not be able to work with such a simple and pleasent engines after hours of running, reasembly and assembly again and running again with ni results…

    Aha, plus diffirend type of air filters to the type of SHA …

    Can anyone help me ??

    All the best to you all !

    Jacek

     

    #710706

    KillerNoway
    Donateur
    Berichten: 192

    Czesc Jacek,

     

    All that matters is the inlet. The best you can do is pick the right carburetor for the right inlet. But you can also run an big carburetor on a small inlet, the injector and airfilter matter. You should pick an 48-50 injector on a 11mm inlet and a 12.7 carburetor, you can also add holes to your air filter for more air but then it will need more gasoline.

     

    Keep in mind that your spark plug should be coffee brown with a little black. If it’s white after 3-5km then it has too less gasoline. If it’s black than it needs more air or a smaller injector.

     

    Kind regards,

     

    Noë  😉

    4-takt krijg de tering, ik rij meng-smering!
    Check mijn perso!
    #710798

    jacekniemiec
    Topic starter
    Berichten: 22

    Hey Noë ,

    Thank You for the tips.

    How many types of inlets there are ? I saw myself two types..

    I have 4 types of SHA carbs : 12.7, 12.10.12.12. and 13.7..

    Somone told me that air filters for 12.12 have 3 holes under the steel round air filter grid..  What about other air filters for other SHA..?

    Im going righ now to mesure the size of the inlets I have .

    Again  – Thank You for the Info !!

    Kind Regoars,

    Jacek

    #710893

    AA-T
    Sleutelbeheerder
    Berichten: 2442

    The last number is the size of the air intake on the carb. So a 12/7 has a 7mm air inlet, a 12/10 a 10mm air inlet and so on.. Smaller airinlets can do with less air going through the filter, meaning the filter with lesser and/or smaller holes..

    I never heard of a 13/7.. Are you sure it isn’t a 13/13?

    #715012

    jacekniemiec
    Topic starter
    Berichten: 22

    Hey AA-T!!

     

    Thanks alot for the info !!

    I will be in my garage for the next few days trying the ‘info’ in practice !

     

    Take care, Friends !

    #715780

    jacekniemiec
    Topic starter
    Berichten: 22

    Friends,

     

    I assumed that the  air  ”inlets” we talking  of the body of motors or air  ”inlets” of the carburators ?

    if air  ”inlets” of the body of the motor then do You know how many types of inlets the Vespa mopeds had ?

     

     

    Best Regards,

     

    Jacek

     

    #716284

    AA-T
    Sleutelbeheerder
    Berichten: 2442

    In my reply above I was talking about the air inlet of the carburator, not the enginecase.

    On the backside of the carburator, where you fit the filter there is a small hole (min 7, max 13 mm). When you use the choke lever this hole is almost entirely covered.

    For stock enginecases the intake is between 10 and 12mm. You can make this 13mm by yourself.

    As killerNoway already mentioned above it doesn’t really matter what combination you use, using the correct jet you can make it all run good.

    You have to look at the color of your spark plug after a few kilometers to see if the jet is correct. A white/grey color indicates you’re using a jet that is too small. A black plug indicates a jet that is too big. A coffee with creamer colored jet indicates the correct jet.

    Using a jet that is too small, the engine will probably not run stationary, but it will run stationary when using the choke lever. Using a jet that is too big, you ‘drown’ your engine and it gets up to speed quite slow.

    An engine that should run faster uses a combination of the larger carb and filter. So a moped that is supposed to run 45km/h will probably use a 12/10 or 12/12 carb. A moped that is supposed to run 25km/h will use a 10/7 or 12/7.

    Let us know if you figured it out 🙂

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