Carby High performance racing carb kit question

Discussion in '2-Stroke Engines' started by racing carb help, May 14, 2016.

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  1. hello,

    So my question pertains to the high performance racing carb I got from bicycle motor works that someone linked on this forum.

    The choke on this carb is built in on a lever. The idea of this is that when you close the choke, to start the engine, it stays closed...but when you throttle, it opens the choke with a spring action.

    I cannot get this to work correctly. It either is full open/close spring action (doesn't stay shut) or stays shut, but won't pop open with the throttle. Is anyone familiar with this carb, and can point me in the right direction of how to install? I've tried to adjust the installed throttle screw on top a few times but have had no luck.


  2. Timbone

    Timbone Active Member

    I prefer the RT carb (a dellorto carb clone) that has the "semi-automatic choke". I've never had the choke work properly. Used to be, I'd click the choke on, the motor would pop, the choke would disengage instantly and the motor wouldn't run.

    Now, the choke tends to stick. The motor fires instantly, I warm the engine up until it wants more air but try as I might to get the throttle to knock the choke off, I have to get off the bike and knock the choke off by using a flat head screwdriver to free the locking pin. Frustrating.

    I have my bike jetted perfectly for 7k high RPM Braaaapppp. Too lean for a choke free start. But I like my carb so what am I to do? I need a manual, controllable choke that will give me a fast. clean start. How can I solve this problem with a low tech, low cost item?

    My solution: I take a thin plastic bag (one of the bazillions that retail stores use) and wrap it around the air filter. Instant choke! The air pressure tries to pull the bag into the filter; it's not going anywhere. After an instant start, the bike will run up and slowly ask for more air. I slowly "undress" the air filter and when the engine is ready to go choke free I stuff the piece of plastic in my back pocket and roll on!
  3. Hello Moto!

    Hello Moto! Active Member

    Yeah mines funny too. If you take the air filter off you'll see a little screw that connects to the choke lever. You can tighten or loosen that screw to get it to hold and release properly. I didn't like the auto full throttle release so what I did was tighten that little screw to where it wouldn't auto disengage. I now have to manually set it to choke position and also manually release it with a little flick to the lever. Pretty simple and efficient little carb though.
  4. Haha

    Haha Guest

    Funny you say that, I accidentally screwed that together a little bit the day I was attempting to install the throttle cable and such. Realized (I thought) it didn't seem to do anything so I forgot about it.

    Thanks hello moto!
  5. 45u

    45u Active Member

    OK I am guessing we are talking about the SHA clone! I run this carburetor with out any problem other then you still do not have a low speed adjustment. If the choke is not staying closed till you blip the throttle you do not have it assembled properly. When you take the top off you will see a leg like part sticking out which is what cuts the choke off and if this is not in place properly it will not work properly. If you are going to loosen any thing under the air filter make sure you use thread lock as it would be really bad if you suck a screw in to the motor. I have mine working properly and did not have to mess with the choke screw.

    The SHA is a OK carburetor and good for those that are new to carbs but there are much better ones out there. My next carb is going to be Mikuni VM Series Round Slide Carburetor 18MM Clamp Mount | VM18-144-WP
  6. skyash

    skyash Active Member

    If you do the cable adjustment up to much which is in wood it hits something in side the can stop it from working that happened to 2 I got so I just undid it a bit