OKO carb going on a Can Am 175

Discussion in '2 smokers' started by Runaway Train, Sep 3, 2020.

  1. Runaway Train

    Runaway Train The Left-Right Tourer

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    I would like to ditch the Bing Type 84 and put on an OKO 26mm.
    I have an OKO on one of my SWM trials bikes and it works great.

    Does anyone have advice or experience?

    My Bing has an off idle stumble that I haven’t been able to cure.

    Cheers,

    Train 5194449E-7376-4BB3-B0F0-C93CC266FB41.jpeg
    #1
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  2. jimroid

    jimroid Long timer

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    Keep in mind that rotary valves need lots of raw fuel to start cold, that is why they have “ticklers” or primers.
    #2
  3. bark sampler

    bark sampler Been here awhile

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    Nice TNT!

    The problem may be as simple as a new needle and needle jet. Those were common wear items. Those choke plungers are the other even more common fail. But that makes it pretty fat, usually more than a stumble.

    I haven’t found anything to work as good as a Bing on my can-ams. But I do have a Lectron I’m planning on playing with on a 280.

    Let us know how it works if you try. I’d suspect it to hurt mid-top power as even a 32 Mikuni was considered restrictive compared to the 32 Bing.
    #3
  4. Runaway Train

    Runaway Train The Left-Right Tourer

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    I’ll keep you posted, I just ordered some gold from Bing Agency International.
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  5. Runaway Train

    Runaway Train The Left-Right Tourer

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    I may have found the problem. The bottom of the plunger enricher was missing a seal, so it was allowing extra fuel off idle and all the was likely. I didn’t know ther3 was one required. As it was missing to begin with.
    So I have replaced the seal, now waiting for bing part# to arrive, then I’ll put it back together.....I really hope this is the smoking gun I’ve been looking for.

    Apologies for the spelling.
    #5
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  6. bark sampler

    bark sampler Been here awhile

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    I’ve had some luck repairing those with cork or gasket material from the auto store. Cork holds up to gas but is a little too soft. Best option is another $30-$35 each in “gold” from the Bing Agency! That is my biggest complaint about those carbs: cost of parts.

    Now any Bing 84 in my garage is stored with the choke/enrichener open so that it’s not sitting in gas or slowly deforming the seal. There were a few years around here where you literally could not get gas without ethanol. Destroyed lots of Bing stuff in my garage even though I drain gas every time.
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  7. Runaway Train

    Runaway Train The Left-Right Tourer

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    Thanks bark, good suggestion. I’ll post as things progress.
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  8. spokester

    spokester Long timer

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    I got a bunch of them plunger rubbers for about a buck apiece for the East German carbs on my MZs. They're sort of Bing copies, I wouldn't be surprised if they fit.
    #8
  9. Runaway Train

    Runaway Train The Left-Right Tourer

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    Thanks for the tip, I cut one out of an old inner tube with a 9mm hollow cutter and glued it in with JB super glue.
    This weekend I’ll get it al back together and see if this is it.

    Stay tuned.
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  10. Runaway Train

    Runaway Train The Left-Right Tourer

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    Ok so I’m at my wits end with this carb. Bike starts and runs great no drama. I snick it into gear and the first ride around the parking lot was great. Put on my helmet and go for a longer ride and it starts acting up. Bogging when I get on the throttle and the bike is under power. I can rev it no problem but a soon as I put it under power it acts up. But it’s not consistent.....The common piece is when it’s under load.
    The spark plug is saying it’s rich, but I don’t know if at idle or under load?
    I adjusted the float it was off by a tiny bit, I should mention that I don’t have the tiny wire that connects the float to the float valve. I can’t imagine that is the problem but I can’t completely rule it out either.

    Damn this is frustrating. The bike ran like a champ on my friends carb with the same jets and specs.
    The OKO option is looking better......
    #10
  11. jimroid

    jimroid Long timer

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    Disassemble your buddy’s carb side by side with yours. Triple examine what the difference is. His carb works, yours does not. You are missing the key. I don’t think inner tube rubber will hold up in fuel, btw, but that would be more long term. Take your time, you will figure it out.
    #11
  12. bark sampler

    bark sampler Been here awhile

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    Another thing to check is the float. Three things there.

    First is the type of float. If it’s off white, it could be getting heavy. If it’s the off-white one you may need to set it so it shuts off at a lower level than you think. If it’s black, it’s the later one and is a little more stable. Second thing: Either way, change the level just a little so that there is a lower level by bending the tab a tick with a flat screw driver.

    Last, while you are checking the level, pull out the float needle and look it over. If the viton tip has a ring, it’s toast. You can sometimes clean them up a little but better off with a fresh viton tip needle.

    My experience is the Bings are a little more sensitive to level than most carbs but once set, should be fine.

    Also, make sure that the air filter is getting air from the back of the seat. You can have the seat too low and starve it for air if you don’t have the rubber spacers on the fender bolts. The seat base can get bent too and choke it out, never happened to me, but it is common.

    I’ll try to think of other rabbit holes to go down.
    #12
  13. Runaway Train

    Runaway Train The Left-Right Tourer

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    Thanks for the tips. I replaced the float with a new white one. The float valve may be leaking and I consider that one next. Gonna fettle with it this week.
    The bings on my Airhead are also finicky for float level, so I am aware of the idiosyncrasies of Bings.
    #13
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  14. Runaway Train

    Runaway Train The Left-Right Tourer

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    So the strange thing is that the off idle stumble is not every time. Just sometimes it is starving for fuel or to rich, I’m not sure. im going to drop the needle to the bottom groove, that should lean it out as the main jest comes on. See what that does.
    seriously though I’m strongly considering the OKO, I’m just really tired of messing with this carb. At this point it doesn’t make sense to me to find another used Bing and swap jets. I think it’s time to cut my loss.
    The American OKO dealer is prepared to provide tech support as this is their first Can Am TNT175.
    It’ll be a winter purchase and a spring test. I’ll post for those that are interested how I make out.

    thanks for the advice so far.
    #14
  15. bark sampler

    bark sampler Been here awhile

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    The other options are a Mikuni or a Lectron. I have build specs for either of those. With either option and likely your OKO, you will need a different boot between the carb and air box. The one used on the 1980 250 MX6 is what you want. You can get them from RTR Moto. The Bing has an abnormally small inlet compared to everything else. I don’t think there is any point in trying something smaller than a 32 or bigger than a 34. The rotary valve intake is 32mm and regulates well enough that a smaller one has no benefit for low end. Those OKO carbs look interesting, reasonable price too.

    For a 34 mm Mikuni, it’s just using the configuration they spec’ed in 1982 on the Qualifier 4. A 32 works but you lose some peak power.

    For a Lectron, a 34 is best but a 32- 36 works, 4/2 without a power jet, 3/2 with. This was a great option until all the used ones shot up in price when the KTM crowd figured they worked good.

    Bummer that Bing has been such a pain. If it’s irregular, it sure sounds like enrichener/choke if that’s still got the home made fix. Is the slide badly worn/sloppy? That can make it hard to tune, but they aren’t cheap either. I think you replaced darn near everything, right? They work real nice when the work, but there’s a demon in that one!
    #15
  16. Runaway Train

    Runaway Train The Left-Right Tourer

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    My slider had about the same wear as the known good carb I used. No more, no less. Yes they are expensive. My enriched rubber has held. The bike has always started without needing the enricher. In fact in the spring I blocked it off and it had no noticeable effect on performance.
    It’s running rich and backing up at idle and the settings are factory. So I’m done messing with this carb it’s going.
    I’ll take my chances with a new carb and the fettling that goes with it.
    #16
  17. bark sampler

    bark sampler Been here awhile

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    On the early TNT Bings you can just block off the whole choke/enrichener circuit with a home made gasket.

    If it’s that fat at 0 to small throttle openings, somethings out of whack on the enrichener, the air screw is plugged, or the float is way to high. That’s about it.

    But keep us posted on the OKO!
    #17
  18. Runaway Train

    Runaway Train The Left-Right Tourer

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    Ok so update. First I’ll start with a big thanks to Doug Gropp for helping me out. Doug is a local tuner with immense experience on Can Ams, mostly flat trackers in the AHRMA. It took three different carbs before we found the right voodoo. In fact he never looked at the specs on the last carb he just said let’s try this one...and then it ran like a scalded dog.
    Then he said just give me fifty bucks for the carb.....and 25 for my time. Three hours worth. Doug helped me go through rebuild the engine a few years ago, and it was really interesting to watch him work.

    I don’t know what the secret actually is, all I know is it’s working. He said a couple times that he has had carbs work fine on one bike then not work on another there are just so many variables.

    Case closed.....
    #18