I ve got an issue with my 2002 Bulldog after doing the basic tuning of carb...


I've got an issue with my 2002 Bulldog after doing the basic tuning of carb jets and the TDM air intake (at the same time I also replaced the old carb intake rubbers). Now to the issue: When the engine is cold it runs poorly when accelerating, almost like a misfire or like it is getting poor mixture. BUT when its warm it runs great. Bike is in the winter garage right now so have not yet had time to investigate properly but given that it works well when warm I'm guessing there is a small air leak somewhere that "closes up" and goes away when the engine is warm? Any suggestions or anyone who has had similar issues?

%d comments
  • Bigger jets? i had 137 jets and my BT drove perfect

  • I've got 135 jets now to match the TDM air

  • I had a Topham kit no TDM air intake, and K&N airfilter

  • Ok. I've got TDM and a hiflow filter, open cans. Runs great warm, not great cold. Any suggestions?

  • Perhaps the rubbers wich hold the carbs are to old and dried out.

    small tear?

  • The carb intake rubbers are new but I suspect I failed to install them and the carbs in them 100% correct

  • I found it a hard job due to the Vtwin

  • I also have done this on my bull

    Tdm air intakebox

    K&n airfilter


    But also removed the aig

    And the exaust (laser)

    Then the dealer did the rest

    Runs Great and beter when its warm

    Had no problems what So ever

    In cold or warm whetter

    Did you try to play with your choke in order to check if its gasoline flow ?

  • Yep tried all choke settings. But don't think it's flow related as it runs perfect when warm?

  • All engines run when warm Nice

    Butt did you disabelt the aig ?

  • Michel Mounir I have not yet disabled the AIS

  • Try to spray deodorant or brake cleaner at the rubbers when the engine is running.

    Does it run faster when spraying a flammable liquid then there must be a leak.

  • More clean air

    And a easy job to do

    The bull likes clean air

    Al you need are two heating endcaps STEEL 12 mm

    Disable the ais/aig

    And mount those end caps

  • Maybe iT runs and sounds like this one

  • And this was a cold start

  • Did you synchronise the carburators ?

    Very important fir a smooth running and idling engine.

    Also :


  • Michel Mounir This has no relation to clear air in the engine. It is not an EGR.

  • Ais / aig / egr

    The same thing

  • Michel Mounir Air Induction System.

  • Jep and i keep forgetting this broos

  • I did not re sync the carbs after fitting the new jets. Thought this was not needed as it runs perfect when warm?

  • Eventually I will remove the AIS to make it cleaner and to hopefully get rid of some exhaust bangs when decelerating, but cant really see how removing the AIS would help with a poorly running cold engine as the AIS simply pumps air in to the exhaust?

  • Fredrik Börjesson You took them out so synchronnising is essential.

    Idling will be better and better response when you touch the throttle.

  • Fredrik Börjesson you are right, there is no relation between AIS and a poorly running cold engine. And you are right, the AIS allows fresh air to be sucked into the exhaust. This is done to reduce the concentration of CO and NOx in the exhaust gas by dilution. And therefore, it does not influence the quality of the mixture in the engine, as Michel Mounir is suggesting.

  • I suggest you concentrate on the mixture during conditions of idling and the beginning of the accelleration. In these conditions, the pilot jet size and the pilot air screw setting are of importance. You probably are in too lean conditions. This is less severe when the engine is heated up. I suggest to replace the 17.5 pilot jets by 20 jets. Then, locate someone that has hardware to measure the percentage of CO. Adjust the pilot air screw so that it reads 4.5%. When doing this, disable the AIS as it will mix fresh air into the exhaust and the CO reading will be wrong. Make certain the carbs are well synchronised, the Bulldog is quite sensitive to that. The International Buldog Forum (mostly referred to as the German forum) has many postings on the air screw setting, the effect of a 20 pilot jet, and on synchronisation. Some members also claim that using platinum spark plugs will help, but I have not noticed a big effect (I use them too).

    I remember that when I removed the carb slide stoppers, installed a TDM inlet as well as a K&N filter, I had identical problems, as well as poor starting behaviour. Now, after I have done all the things I suggest to do, it starts immediately and picks up from idle smoothly, even when the engine is cold. Oh, and by the way, I also removed AIS, because of the cleaner looks.

  • Thanks for the very extensive answer.