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Pulsar air-screw on Machismo 350 (and poor performance)

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  • #1

    Pulsar air-screw on Machismo 350 (and poor performance)

    When I first serviced my bike, which i inherited from my brother, at Southern Motors, Anna Nagar, Chennai, the mechanic said the air-screw is stuck in the carb and that they'll have to remove it to adjust the air-fuel mix. So they took it to a lathe/furnace, did something and removed it. I thought they'll put it back in, but the @#$%!^&*s replaced it with a Pulsar air-screw. After that, I began to service it regularly at Jaf's at Pudupet, Chennai, who is(was) considered the best authority on RE vehicles in Chennai. Atleast 75% of Madras Bulls members service their bikes there. It was there that I got to know about this air-screw issue.

    BTW, it is a 2002 RE Machismo 350.

    Now to the problem: The guy told me that Pulsar air-screw has only 7 windings while the Machismo's air-screw has 13. So right now the air-fuel mix might be too rich. I am getting a mileage of about 20-22 kmpl (which is waay low for a UCE) and the bike struggles to go above 95 kmph. In fact, it cruises at 80 kmph, which I feel is too low for that bike. I have a feeling it is because of the bad air-fuel mix. Acceleration is okay, because I can hit 80 quickly, after which it gets winded.

    My question is, am I right with my guess about the issue or am i shooting in the wrong direction here? If I am wrong, what could be the issue with the bike? I'm sure the bike could perform better, because I've personally felt it when my bro rode it when it was new.

    When I asked the guy to put a new bullet air-screw, he said RE does not supply it separately, so i'll have to replace the entire carb, which'll cost me Rs. 3500. I'm not happy at replacing the entire carb for a single screw. So, any suggestions? Hoping you guys can help.
    Tags: None
  • #2
    Query Approved.
    :)

    Comment

    • #3
      ^^ yup its true that the air fuel screw does not come separately. What you can do is try the ZMAs carb screw and see if that fits, or else the new P220 carburettor runs a BS29 CV carb, so the tuning screw should be the same.


      My offerings to the gods of speed -

      - KTM Duke 200
      - Yamaha RXZ 5 speed


      Comment

      • #4
        Originally posted by jd666 View Post
        ^^ yup its true that the air fuel screw does not come separately. What you can do is try the ZMAs carb screw and see if that fits, or else the new P220 carburettor runs a BS29 CV carb, so the tuning screw should be the same.

        Okay. Thank you. I'll look into that.

        And thanks for pointing me in the right direction. I did some research and found that the Machismo 350 has a BS26 CV Carb. The Machismo 500 has the BS29 Carb. The pulsar 150 uses the BS26 Carb, so, I guess that ain't the problem. Maybe the mechanic was BSing with me. Or I need to learn a LOT more about bikes (Which I definitely do).

        Btw, does the rich fuel mix affect both mileage and performance?
        Last edited by Udayakiran; 03-04-2010, 11:37 AM.

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        • #5
          Originally posted by Udayakiran View Post
          Btw, does the rich fuel mix affect both mileage and performance?
          Lean means more air, less fuel. Rich means more fuel(better performance), less air
          Smoke rubber,not tobacco.

          -Life Through-the-Lens
          -For HELLA/VALEO [BMW/AUDI/FORD/LINCOLN/SKODA],P220,Aftermarket Projectors,pls contact me!

          Comment

          • #6
            @udaykiran - rich fuel mixture will make your bike go like a rocket, but will deposit carbon on the sparkplug, face of the piston, exhaust port, valves etc. And it will also reduce the mileage. so better to stick to the ideal mixture setting than to mess with it, unless for a specific reason.


            My offerings to the gods of speed -

            - KTM Duke 200
            - Yamaha RXZ 5 speed


            Comment

            • #7
              Originally posted by jd666 View Post
              @udaykiran - rich fuel mixture will make your bike go like a rocket, but will deposit carbon on the sparkplug, face of the piston, exhaust port, valves etc.
              but tht is only if its tuned improperly right?
              Smoke rubber,not tobacco.

              -Life Through-the-Lens
              -For HELLA/VALEO [BMW/AUDI/FORD/LINCOLN/SKODA],P220,Aftermarket Projectors,pls contact me!

              Comment

              • #8
                ^^ that is if its tuned too rich. you have a rich to lean range. ideal range is 14:1 ( 14 parts air, 1 part fuel), depending on the setup of the engine and the requirement, the ratio can be set as rich as 12:1, and for economizing and compromising on performance, as lean as 14.5-15:1. But thats is all numbers. A general bullet mechanic will set the CV carb to about 2-2.5 turns out depending on where he gets the most steady rhythm of the engine and the idle is most stable, not rising and falling.


                My offerings to the gods of speed -

                - KTM Duke 200
                - Yamaha RXZ 5 speed


                Comment

                • #9
                  Originally posted by RanjithMN View Post
                  Lean means more air, less fuel. Rich means more fuel(better performance), less air
                  I understood that, but i was wondering if a too rich mixture is used, will it reduce the performance?


                  Originally posted by jd666 View Post
                  @udaykiran - rich fuel mixture will make your bike go like a rocket, but will deposit carbon on the sparkplug, face of the piston, exhaust port, valves etc. And it will also reduce the mileage. so better to stick to the ideal mixture setting than to mess with it, unless for a specific reason.
                  Okay, But how do I find if it is ideal?

                  Comment

                  • #10
                    Originally posted by jd666 View Post
                    ^^ that is if its tuned too rich. you have a rich to lean range. ideal range is 14:1 ( 14 parts air, 1 part fuel), depending on the setup of the engine and the requirement, the ratio can be set as rich as 12:1, and for economizing and compromising on performance, as lean as 14.5-15:1. But thats is all numbers. A general bullet mechanic will set the CV carb to about 2-2.5 turns out depending on where he gets the most steady rhythm of the engine and the idle is most stable, not rising and falling.
                    2-2.5 turns? So the story of the Bullet air-screw having 13 turns and the Pulsar air-screw having only 7 turns and that affecting the mileage is all pure BS?

                    Comment

                    • #11



                      Any idea what this tube is? And where it connects to? I found it hanging loose, along with the speedo and amp meter smashed after returning from a long trip. I have the feeling someone might have thought it is the petrol tube, which is on the other side, and tried to drain it.
                      Last edited by Udayakiran; 03-06-2010, 06:30 PM. Reason: Picscrazy messed up my pic, so trying with Imageshack.

                      Comment

                      • #12
                        Originally posted by Udayakiran View Post
                        2-2.5 turns? So the story of the Bullet air-screw having 13 turns and the Pulsar air-screw having only 7 turns and that affecting the mileage is all pure BS?
                        it depends on the length of the tuning screw as well. 2-2.5 turns is un-screwed from the screw being fully tightened, now if your screw is not long enough, then 2-2.5 turns out will only make it more lean.


                        My offerings to the gods of speed -

                        - KTM Duke 200
                        - Yamaha RXZ 5 speed


                        Comment

                        • #13
                          Originally posted by jd666 View Post
                          it depends on the length of the tuning screw as well. 2-2.5 turns is un-screwed from the screw being fully tightened, now if your screw is not long enough, then 2-2.5 turns out will only make it more lean.
                          OH! Okay. So how would you suggest me to handle this problem?

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