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Help MC22 not starting

Discussion in 'Honda 250cc In-line 4's' started by markcm02, Oct 9, 2021.

  1. GeorgeT

    GeorgeT Member

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    Definitely incompatible. The full-thread one will hit the piston. If that was in all cylinder heads the engine would probably not even be able to rotate!!!!!!
     
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  2. markcm02

    markcm02 Member

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    good good, glad I checked before chucking them in. At least they make good spark testers
     
  3. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Yes, 2+ turns out is common on CV fuel screws. By the way, the easiest carbs in the world to tune by ear are Bings on a BM. They should never need to be set by 'n' turns out.
     
  4. markcm02

    markcm02 Member

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    So I went to go do the compression test however the kit that was leant to me does not contain the correct fitting for my 10mm plugs :( off to Bunnings to try find an adapter

    edit: Bunnings not super cheap had an adapter so I am stuck
     
    Last edited: Oct 10, 2021
  5. markcm02

    markcm02 Member

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    I have inspected all choke plungers and the look clean, can’t find any debris
     
  6. GeorgeT

    GeorgeT Member

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    Yeah, what I used to do was basically tune each cylinder by removing the spark plug lead on the other one. Just adjust the mixture until the engine feels like cutting out then do the other one. Then connect both and she (R100/7) ran so smoothly I could stand a pencil up vertically on the tank and it would not vibrate off. I remember going to a vintage race meeting at Oran Park where Don Wilson had a couple of his BMs running next to me and I didn't even know they were running until he told me they were. Just the people chatting around drowned out their motor noise. Don was a magician when it came to BMs.
     
  7. markcm02

    markcm02 Member

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    I can get it to a point where if I hold the starter for an extended amount of time I can get it running and then it will run at very low rpm by itself for a couple seconds then die. This is with choke fully out and idle screw at varying levels including max
     
  8. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Doing that with the choke open for so long can foul the plugs and/or flood the engine...

    Dry out and clean the plugs, try a little bit of choke (not full) and a little bit of throttle. If it starts to fire, keep everything where it is and hold the button. Very slowly try to roll on the throttle a little bit.
     
  9. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Last edited: Oct 11, 2021
  10. markcm02

    markcm02 Member

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  11. markcm02

    markcm02 Member

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    Cleaned plugs and started with half choke and a tad of throttle and engine roared to life but did die after a couple of seconds I would have held it however it’s getting a bit loud and these things definitely aren’t quiet. So until tomorrow :)
     
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  12. DannoXYZ

    DannoXYZ Well-Known Member

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    Did you poke out lateral bleed holes in emulsion tube and pilot jets with matching size copper wire? Dried petrol varnish turns to plastic and cannot be dissolved with modern carb-cleaner spray that lacks chlorinated compounds.

    Same with poking out bleed holes in carb venturi. Bend tip of wire 90-degrees 5mm from end and reach down carb throat and floss out all bleed holes (remove AF-screw 1st so it's not blocking hole). You'll find copper-wire pushes out dried petrol plugs from these holes like little grains of sand.
     
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  13. markcm02

    markcm02 Member

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    I did inspect all the injectors but I could not inspect the Venturi hole, so I’ll pull the carbs off again and try and dig out if there’s anything there.
     
  14. markcm02

    markcm02 Member

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    I haven’t pulled the carbs off yet but just cranking it, it sounds like it’s so close, like I could hear some cylinders firing but it just never picked up. I’m gonna go through the carbs and clean them as thoroughly as possible
     
  15. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    That is just totally confusing :idk:
     
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  16. markcm02

    markcm02 Member

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    I think its because I had used some carb cleaner on Mmmmm on the plugs and so it used it for fuel. So a complete fluke because I can’t get it to happen again tonight. I am as confused as you are
     
  17. markcm02

    markcm02 Member

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    So I think current issue is one of my carbs (#1) is not getting fuel. Because I’ve managed to “drain” the bowl of carb #1 and comparatively not much is coming out.
     
  18. DannoXYZ

    DannoXYZ Well-Known Member

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    Need to split carbs. Scrub out fuel-rails, one going to #1 may be clogged with petrol varnish. Also replace fuel-rail O-rings while you're there.
     
  19. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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  20. markcm02

    markcm02 Member

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