Dumaguete Info Search


bike carburetor help, anyone?

Discussion in 'Science and Technology' started by kelpguy, Oct 29, 2019.

  1. kelpguy

    kelpguy DI Senior Member

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    looks like i messed up doing a carb cleaning.
    following a complete disassembly and cleaning, the motor dies immediately when i accelerate normally. it will accelerate normally if i do it very slowly.

    i had two bike mechanics look at it and 1 guy got it to accelerate normally by plugging ±4mm air port on the carb throat rim but now it runs rich and smokes.

    ideas?
     
  2. Jack Peterson

    Jack Peterson DI Forum Luminary Highly Rated Poster SC Connoisseur Veteran Air Force

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    Sounds to me you have an Automatic choke problem,
    Most Shop mechanics do not like Stripping modern carbs as they are Factory set and sealed, a slight bad Fix and it will take air in and make the choke act up. :thumbsup:
     
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  3. OP
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    kelpguy

    kelpguy DI Senior Member

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    tnx, jack. the bike, a Yamaha SZ (2014), has a manual choke which has been disconnected for years. the bike starts with a touch to the starter button and idles perfectly, it's the acceleration that is a problem.
     
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  4. Jack Peterson

    Jack Peterson DI Forum Luminary Highly Rated Poster SC Connoisseur Veteran Air Force

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    Might sound silly but have you tried a new or different spark Plug, you say it is smoking so I wondered if is Oiling up on Idle, also it may be a Scraper ring problem?
     
  5. Catabisis

    Catabisis DI Junior Member

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    Just replace the carb. You can probably get one for under P900. My 6 year old bike is on its second
     
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  6. Philpots

    Philpots DI Member

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    Sounds to me like a bypass jet or feed is blocked. If you cleaned it maybe you blocked that small hole in the process. And if the problem started immediately after you disassembled the carb I really don'k thing it will be rings or plugs. New carbie looks good at that price or take the thing apart and have a really good look at everything. You missed something that's for sure.
     
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  7. RR_biker

    RR_biker DI Senior Member Veteran Marines

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    There's a carburator repair kit for around 250 peso with the most essential spare parts to be replaced.
     
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  8. Philpots

    Philpots DI Member

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    Yup but I think he missed a bypass jet or something like that. Acceleration requires a bit more more fuel that just coasting. I am assuming that the bike can eventually get up to speed from idle or does it just die when the throttle is opened?
     
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  9. OP
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    kelpguy

    kelpguy DI Senior Member

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    thanks for the input guys...

    i'm still putzing with the carb but here's the story to date;

    the bike is a 2nd hand Yamaha SZ 2014
    the carb is a Mikuni 1PM1 00 C4601. the locals call it a diaphragm car and they don't like this type of carb.

    i checked with Yamaha and no less than 10 shops in the area including FS&O and Raddi, and aftermarket carbs and rebuild kits specifically for that bike/engine aren't available. i also checked with a vender on Lazada that lists a lot of carb kits. (not available)

    yamaha wants ₱8k for a new carb; an aftermarket carb is under ₱2000
    yamaha wants ₱1500 for a only a high speed jet

    a couple of bike shops said a mio carb would fit but they said no go because there's no electrical connection. i never did find out what the electrical connection does but it looks to be a heat sensor cuz a red colored engine block looking icon in the instrument panel lights up when i disconnect the cable. the connection is mounted near the choke and looks to be coupled to it, maybe it chokes/shuts down the engine if the motor gets hot? the bike runs the same with the electric thingie disconnected or connected. do i need it?

    the manual choke cable was disconnected when i purchased the bike and i never needed a choke to start the bike.

    in theory; shouldn't a rebuild kit fix a carb if it's the body isn't warn?; this bike only has 17k on the odometer.

    i agree that something is blocked, i suspect it's in the high speed ports but we haven't been able to fix it.

    2 bike mechanics have tried to fix it and yesterday, a very meticulous bike mechanic and his two knowledgeable companions spent more than 3 hours yesterday trying to find the problem.

    next is looking for an aftermarket carb that will fit.

    on a side note;
    that particular carb is notorious for leaking from the float bowl due to the float valve needle and seat not working properly. yamaha can get a new n/s but it takes 3 months; i waited 5 months and gave up and it's the same n/s combo as the oem. quite by accident, i found a needle and seat in a Suzuki Raider 150 carb rebuild kit (₱110) that looked to be the same dimensions so i took it to a machine shop, had them remove the SZ n/s and press in the Raider n/s and that fixed the leak problem, so far.. the float bowl cover gasket interchanges also but unfortunately, the jets in the raider kit don't fit in the SZ.
     
  10. Philpots

    Philpots DI Member

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    Mate you are certainly learning a lot about carbs. Best of luck.
     
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