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93 Carry DD51T Carb Tuning

Discussion in 'Suzuki Carry' started by Cole, Aug 6, 2017.

  1. Don-in-Japan

    Don-in-Japan Member

    Just to clarify.. your CO fine adjustment is the air/fuel mixture screw. Adjusting this is the "Meat and potatoes" of carb tuning. It can be done in while an emissions tester is reading HC/CO, but that's a bit of a "Lab tune" for passing the tests for JCI inspections.

    Here's how to do it..

    -Pull the adjusting screw all the way out to inspect. It should have a smooth taper, and be clean. Sometimes, it will need replacing due to super mechanics torquing it down too tight.
    -Re-insert, and GENTLY snug it down until it bottoms out.
    -Using the flat tip slot as a guide, turn the screw CCW 2 complete turns. Turn the vehicle on, and let it warm up.
    -Once it is warmed up, turn the screw CCW in very small increments.. say 1/8 of a turn
    -The idle will slightly raise with each turn of the screw
    -You will get the the point where the idle no longer raises.. turn it CW until you hit the point where it first stopped raising the RPM's. You want it right on that crest.

    If you have a spare vacuum gauge, it will do the same job. Adjust until you see max vacuum on the needle.. but no further. Any more will just introduce too much fuel.


    Of course the adjustment screw is independent of any of the other physical adjustment screws.. just thought it would help to clarify.
     
  2. Cole

    Cole Member

    Thank you very much for clarifying!! I am definitely not an expert just a guy trying to learn. Any information is really appreciated! I'll have to go through this on mine. I have been noticing it running rich. Thanks again and I love how people come together here and colabirate to build a good resource for these trucks!!

    In the tuning process would you suggest adjusting this after you have gotten the base idle and choke set?
     
  3. KCCats

    KCCats Member

    Yes and start with the idle down as low as possible once it is warmed up!
     
  4. Don-in-Japan

    Don-in-Japan Member

    Correct.. when the mixture screw is 2 turns CCW, you may have to play with the idle stop screw to get a good baseline RPM for mixture adjustment. Start at around 500-800rpm (whatever is stable for your vehicle.. these are 3 cylinders after all), then do the turns. You'll likely end up at 1100-1200 RPM's when done (or more.. depends on vehicle). Then re-adjust idle to a happy medium, and make any other adjustments as per your write up.

    Consider too.. that this is assuming typical behavior from a healthy carb. If you start getting missing problems, erratic idle, or no changes in idle while adjusting mixture screw, the carb likely needs an overhaul. No amount of tuning and tweaking is going to help a crappy carb.. it's like trying to tune a $5 guitar.. might stay in tune for 10 minutes, if at all.
     
  5. Cole

    Cole Member

    Awesome! Thanks
     
  6. rugerman

    rugerman Bronze Supporting Member

    Hey guys where exactly is that air mixture screw you are talking of. I am farmiliar with how to tune but don't see it.
     
  7. rugerman

    rugerman Bronze Supporting Member

    I think I see it back there.......... whew.
     
  8. Cole

    Cole Member

    It is located between the 3+2 or 2+3 vacuum hose take offs on the carb near the intake mainifold.
     
  9. rugerman

    rugerman Bronze Supporting Member

    Mine was already set as good as it was going to be.
     
  10. KCCats

    KCCats Member

    Hey Oriely's only has the 5/64 stuff will that work for vac lines?
     
  11. Cole

    Cole Member

    It looks like 5/64 is just under 2mm. So I know the 3mm tuning was a snug fit. I would probably say you will have a hard time with it.
     
  12. Durb

    Durb New Member

    I have noticed in my search for new carburetor that the only one I can find that looks like my 3+2 is used and very expensive. I have found several new ones but all the choke actuators etc are different. What should I be concerned with when looking for a new carb. Thanks for any advise.
     
  13. KCCats

    KCCats Member

    I had found one on Ebay for $107 but the choke was different and wasn't sure on all the vacuum lines?
     
  14. Cole

    Cole Member

    I guess first question is why exactly you think you need a new carb. There are several different rebuild kits out there and all the information is on here now to tune it.

    If you are set on replacing I would stick with a factory replacement no matter the price. There are some threads that cover replacement with a 3+1. I guess the best thing to ask yourself is how much is you frustration worth? Personally I would spend a few hundred more to not even think about it.
     
  15. KCCats

    KCCats Member

    Then there is that EFI system that Fred mentioned for about $800
     
  16. Durb

    Durb New Member

    Mine has some mounts that are broken for diaphragms and has too many of the choke components missing
    Also what would be the difference of a DD51T and a DB51T carburetor because I have yet to find a DB51T carburetor that looks any thing like what's on my truck
     
  17. fmartin_gila

    fmartin_gila Active Member

    You say you have not found one that looks like what is on your vehicle. Are you positive that what is on there is what should be on there, or has someone already done some messing? Hard to guess what has transpired over the years to these vehicles.

    Fred
     
  18. Durb

    Durb New Member

    I'm pretty sure it is the original it's just when I search carburetor for a DB51T all that pulls up have different vacuum configurations but the carbs for Dd51 seem to look very similar to mine. When I see a used carb for for the DB51T it looks correct. I don't see a reason to buy an used carb for twice the money with who knows what kind of problems it has when a new one is half the price. It's not so much the cost as getting a good working carb. Trying to figure out if there is difference in carbs on the different models or do I just stick with the F6A engine group.
     
    Last edited: Oct 7, 2017
  19. Cole

    Cole Member

    Well I don't know for sure but it wouldn't make sense to me for different models with the same engine to have different carbs. I would think that all F6A would have same carb setup, being that it is specific to the engine.
     
    Last edited: Oct 8, 2017
    Durb likes this.
  20. Durb

    Durb New Member

    Cole I wanted to say thanks for all the info in this post. I ordered a new Carb out of Hong Kong that was a modern version of mine and with only a few mods to it was a great replacement. The hardest tuning issue I had was getting the Choke Plate adjustment made. It was remaining at almost full choke and after several adjustments I have it close and may have to do some fine tuning as the weather gets colder. After getting it set I followed your tuning tips and it worked fine. The truck starts with just a bump of the key and goes through its warm up procedure great. The only thing left for me to find is the accessory idle up vacuum line. I'm not sure were the vacuum switch is located that operates this feature.
     

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