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Air intake leak - effects?

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by jd, Feb 21, 2006.

  1. Decided to strip the Kat down the other day to give the carbs a bit of a clean out - been running fine just decided to do it for the sake of it. First annoyance was the realisation that the Kat airbox goes in before the engine, and being larger than the frame wasn't going to come out (curse you Suzuki). Anyway worked around it and discovered that the rubber tube connecting the airbox to one of the carbs was leaking - not surprising since that one was being held on by a cabletie and not a proper clamp :shock:. Anyway fixed that (and replaced the fuel line whilst I was at it) and I've already noticed that the engine runs better, especially at low revs (had to drop the idle speed) but can't quite work out how an air leak affects the engine like that. Anyone want to give me the technical explanation?


     
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  2. Simple really ( and no im not being smart ect )

    But "that" little air leak would have been upsetting the very fine air/fuel mixture at idle making it run 'lean' ie more air than fuel , you'll probably notice at lower speeds the bike should run a little cooler now as well.

    That air leak would have been changing the higher rev air/fuel mixture as well but less noticable :)

    hope this helps you out alittle

    Rob
     
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  3. That's sort of what I was thinking, but it'd be more to do with a change in the air pressure/flow than an actual change in air volume though wouldn't it? No idea on how engine temp has been affected, no temp gauge on the Kat and its air and liquid cooled anyway so overheatings never been an issue. Just hoping it's the cause behind my increase in fuel consumption in the last few weeks.
     
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  4. air leak

    I had an old YAMAHA XJ900 years ago and noticed that on the exhaust header of 1 pipe it was all white right where it comes out of the exhaust port on the head,I asked people who know more than me about these things than me and they said that there was a leak in your intake manifold which is causing too much air to be coming in the intake of that cylinder,increasing the air fuel mixture(any combustion needs air to go boom and the more air,the more boom but obviously there are limits to the ratio of air/fuel before combustion cannot occur)
    This in turn was causing the valves to burn the air/fuel mixture at a higher temperature because of the excess oxygen and thus the white hot scarring around the exhaust pipe.Thats how you get burnt exhaust valves and expensive head reconditioning bills. :cry:
     
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  5. If it was between the airbox and the carbs it shouldn't have made much difference. One carb may have been getting more air, therfore running more lean, but really it shouldn't make much difference.

    One thing I find on these Japanese 4's is they run really smaller idle jets.

    Cleaning the carbs can dislodge small bits of gum and make more difference then you realise.

    The idle jet effects more of your riding then most poeple give credit. you notice a difference when you get them right, because they come into play when you crack the throttle.
     
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  6. Ah ha - that's what I'm noticing (guess the carbys were dirtier than they seemed). Before when I cracked the throttle at lowish revs the engine would sometimes bog down and be reluctant to accelerate, but it would usually come good after a decent run at higher revs
     
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  7. Yep air leaks in rubber definatly affect the running :grin:
     
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