Tuning carburetor on 1992 CA tw200
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Thread: Tuning carburetor on 1992 CA tw200

  1. #1
    Junior Member efnick's Avatar
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    Tuning carburetor on 1992 CA tw200 (updated 7/11/19)

    Hey guys, im almost happy with where this bike is at, but i do have a stumble at WOT (wide open throttle) heres the rundown-

    1992 CA compliant tw200 (stock)
    got in non riding condition, checked electrical seems ok for the most part, battery holds a 11.6 voltage overnight after being on a trickle charger and at idle is around 12.5v, 13.5v with revs

    took off carb, cleaned all jets and slides, pulled air idle mixture plug and checked- factory setting was 1.5 turns out, adjusted to 2.5 but way too rich, now currently around 1.80-2 turns out. Removed top cap and slide assembly/ needle from carb, shimmed the needle with (2) M3 washers (approx .03mm thick total). Now starts without choke at that setting and idles without dying (it was sputtering and dying at idle before and required choke on a warm day with bike in the shade), it will bog if i whip the throttle open immediately, but if i roll the throttle on it revs perfect and multiple throttle whips after its off idle yield immediate response. When riding, throttle response is fantastic, however, if i twist throttle to WOT is bogs, sputters, looses power pretty much immediately. If i roll the throttle up through the revs smooth it seems OK, but throwing it into WOT seems to create a lean condition.

    What brand is the stock carburetor on a 1992 CA model? What is the stock main jet size on this bike, as well? I tried looking when it was apart and couldnt read whatever was stamped on it. Will a 130 main jet for the newer model tw200 be too much for this bike? Thanks!
    Last edited by efnick; Yesterday at 01:54 PM.
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  2. #2
    Ken
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    Welcome. I have a 1993 and the only issues with the carb that I have had was a thumping at wide open throttle. That was caused by a lean condition/ not enough gas for that speed. My carburetor boot was bad so I was getting too much air which only really affected it at WOT full speed. I sealed up the intake and never had another issue. The next size jet bigger may not hurt but since these bikes are not ran WOT much it would probably just hurt your mileage without much increase. Your lower rpm issues I think you probably didn't need the shim. Using the choke isn't bad. If mine has been sitting even when it is hot I usually have to put the choke about 2/3 out, it cranks and push the choke off and take off. I tried another carb for experimental purposes and mainly it was too rich. I reinstalled my stock carb and it runs great. Play around with the air fuel screw as it does slightly affect some of the other speed ranges also. At least these carbs are easy to get to. Good luck.
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    1993 TW200 just shy of 46,000 miles

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    Junior Member efnick's Avatar
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    thank you for the feedback- after i initially cleaned the carb and before i added shims or adjusted the idle mixture screw, pulling the plug yielded white residue on the very edge of the plug filament, and white residue from the end of the arc all the way almost to the base of it. Now, since riding it (for a very short period of time) with the shims and air fuel adjustment, those areas are a mocha brown color. im also getting a much more responsive throttle while riding, primarily mid-range where one tends to cruise most often. I also have an issue with the air box boot being old, and im assuming, hardened and shrunk. it does not fit snug over the entire mouth of the intake side of the carb, but barely touches it all the way around the edge, so perhaps that it affecting the top end/ WOT. are these tubes for the older tw200 available anywhere, and is there a temporary fix or that, such as wrapping with electrical tape, or is that just going to make a mess?

    also just to note- i am at about sea level.

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    Ken
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    That air box boot and all sounds like your issue. That is pretty much what mine was. I rigged mine somehow with alternate rubber tubing. I need to order the stock one. Partzilla, Bike Bandit, [email protected] cycles etc. Just look around.
    1993 TW200 just shy of 46,000 miles

  6. #5
    Junior Member efnick's Avatar
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    well, i wrapped that area with electrical tape and took it for a spin and noticed no difference. i removed electrical tape and at idle i sprayed some carb cleaner on that area, and there was no change in idle speed (that i could tell).

  7. #6
    Junior Member efnick's Avatar
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    Pulled off the second needle spacer, so theres only a single spacer added to the needle, then took it for a 6 mile ride and pulled the plug-
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  8. #7
    Senior Member SportsterDoc's Avatar
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    I am not a fan of shimming a needle, instead preferring a richer (skinnier) needle if needed.
    That is not to state that it cannot be made to work, but the profile will be off.

    Surprised that it does not like mixture of 2.5 turns from gentle seat, but behaved non-WOT in mid-range.
    Is enrichener not seating?

    How did it behave with one of the two shims removed?

    Are you sure that WOT is lean...balking...hesitating
    versus blubbering from being too rich?

    Before pulling the spark plug, how was it run?
    ...and did you cut power and coast to a stop?

    See the first link in post one of this thread:
    https://www.tw200forum.com/forum/tec...agnostics.html
    Last edited by SportsterDoc; 06-30-2019 at 07:37 PM.
    2014 Honda CB1100
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    1976 Honda CB750F
    1975 Honda CB360
    1970 Yamaha CT1
    1972 Yamaha CT2
    1972 Yamaha AT2/CT2
    1970 Honda SL350
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    1962 Honda CA110

  9. #8
    Junior Member efnick's Avatar
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    I believe what led me to think it was a lean condition was before i shimmed the needle, and before i pulled the brass plug and adjusted the idle mixture screw, it was a little difficult to start the bike, the bike required nursing at idle in order to not die when cold and warm, and when i pulled the plug after riding around the diode had white residue on the tip, and the arc had the white residue all the way down to the threaded shoulder.

  10. #9
    Senior Member SportsterDoc's Avatar
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    This was my 2 cents 2 1/2 years ago

    Off the showroom, it required choke (enrichener actually, on the TeiKei MV28 carb) for warm starts and it had idling issues ...deceleration diaphragm seemed to affect fast idle...when it dropped to "normal" it would die on the 18 mile ride home. Drilled the plug and adjusted from factory 1 1/4 turns out to 2 3/4 allows restarts, even after 2 hours sitting in ~65 F ambient...and ended idle issues. Pilot, needle and main jets seem OK up to 5,000 feet elevation (home is 2,200)

    Stock jetting was fine up to 8,500 feet
    2014 Honda CB1100
    2018 Yamaha XT250
    2016 Moto Guzzi V7 II
    2017 Yamaha TW200
    2012 Triumph Bonneville
    2002 H-D Sportster 1200 Sport
    2003 H-D Sportster 883
    1976 Honda CB750F
    1975 Honda CB360
    1970 Yamaha CT1
    1972 Yamaha CT2
    1972 Yamaha AT2/CT2
    1970 Honda SL350
    1970 Honda CL350
    1967 Honda CL160
    1967 Honda CB160
    1962 Honda CA110

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    “Rip and strip” the air filter – until then, none of this makes any sense - P.S, your battery is knackered ....
    Last edited by Purple; 07-01-2019 at 11:42 AM.
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