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Air-box versus Pods

Trojan441 Jun 10, 2019 at 2:07 AM

  1. Trojan441

    Trojan441 Well-Known Member

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    Just finished reading an old technical article on "Kwacker" 4 cylinder engines and here an crucial point.

    It states that the Carburettor to air-box rubbers being sealed, which they obviously have to be against air leaks; importantly form part of the total length of the Inlet tract & therefore you would/could assume if the original equipment is replaced by pods, the original formula for the engines breathing goes out the window, so to speak!
     
  2. Trojan441

    Trojan441 Well-Known Member

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    Carburettor Specifications for the 600s; ZL 600 A; ZX/ GPZ 600; GPX 600;

    Bought every manual I could find on the 600 500 400 4s I have Kawasaki own publications on the ZL 600, GPX 600, GPZ 600, Haynes 400, 500, 550 Air-cooled Fours, ZX 600 /& ZX 750 Liquid -Cooled Fours & was looking @ Carb' data across the board as importantly may have a set of Californian carbs!
    Interested b'cos of the bike originating as a Californian model looking @ how possibly the internals may be different so when I strip the Keihin's down no surprises! Also perhaps they could be tweeked for performance gains!
    Apart from the nominal choke size of 30mm on the ZL's all the other 600's are 32 mm.
    The main difference is a smaller Main Jet on the ZL's and all the others Machines having values of /from 105-108

    On the Emission controlled Californian models according to the manuals; any Californian models should differ in this way: ;
    ZL 600 A Californian model:
    Main Jet 92; ZX108;
    Jet Needle Zl N27X; ZX N52T
    Pilot Jet 35;
    Pilot Air Jet 160;
    Starter jet/ Choke jet 42/48. Later on Post 1989 ZX 52
    Needle Jet size of 6.


    ZL 600 A Standard model:
    Main Jet 90;
    Pilot Air jet 160; this is bigger than the other. ZX 600's @ 145/150.
    Jet needle is N27L found on the GPZ & ZX 600 models too GPX N52Q,;
    Needle Jet size of 6; I can't find this listed anywhere else on the Liquid-Cooled machines apart from the earlier Air-cooled 400 & 550 fours!
    Starter/Choke jet 52; Standard ZX/ GPZ 45;
    Air jet across the board is standardised @ 100 on all 600 cc models;

    Carburetors specifications can be divided into Pre-1988 Models & Post 1988 models, with some ZX adjustments in 1989.

    Not sure how the lower Bhp 1990s ZL 600 B fits into this tabulated data, but carb' spec's may explain the Bhp drop from ZL 600 A 73.4/7 to 61 Bhp for the ZL 600 B! a big difference no less.

    ZL 400 data is hard to come by & mainly in Japanese!
     
  3. COTTONTOP

    COTTONTOP Member

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    I do like my pod setup as I was forced to get them as my ZL600 had them on it when I got the bike. Much effort and experimentation though was needed to get it to run good.
     
  4. Trojan441

    Trojan441 Well-Known Member

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    Glad u eventually got your bike sorted and now perhaps we can all understand why it is so difficult to fit pods n' get them tuned right 4 the four cylinder engines.Aesthetically, though, when the fake chrome air box panels are missing do u not think something doesn't look right?

    Did U know the last of the GPz /ZX 550's did a quarter of a mile almost as fast as the Z1 Cycle Magazine test 12.65 S 104.16 Mph! And then the GPX 600 came along 11.7 seconds n' quicker too!

    What I really would like for fun is an strong flexible motor 80 + Bhp ZL 600 A, maybe through carb' tuning n' plus the GPX crank n' barrels n' pistons will get me there! Also it would be about 100 lb lighter than the Z1.
     
    Last edited: Jun 10, 2019 at 4:15 PM
  5. COTTONTOP

    COTTONTOP Member

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    I don't know how much horsepower I am pushing on my '86 ZL600 but it sure breathes and runs throughout all of the gears.
     
  6. Ed

    Ed Active Member

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    As far as I know, only the ZL600A (maybe not all regions but US for sure) models used less restrictive mufflers and intake snorkel. Those are the two things that mainly determine jetting and HP since all other parts are common to both. You can measure the exhaust outlet and snorkel to see the difference. I've only seen pictures but it would be nice to know the exact diameters of each.
     
  7. COTTONTOP

    COTTONTOP Member

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    I will check into it. The supplemental manual says 75 hp @10,500rpms for a ZX600-A1 which is the same manual they tell you to use for the 1986 ZL600 A. They also have the 32mm carbs that I put on my ZL. I have also taken off all of the emission stuff . I also installed a manual fuel petcock to get rid of the vacuum port which can be a pain at times if the diaphragm splits. I also took the check valve out of the fuel cap. No fuel starving problems now. I also put a taller tire in the back to a 150-90-15. It fills up the gap between the rear fender and gives me more bite to the pavement.
     
  8. Trojan441

    Trojan441 Well-Known Member

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    I have a set of ZL 600 A Silencers/mufflers on the ZL400 now!
    My ZL 600 A is 1986.
    My ZL 400 A is 1987.

    Snorkel? Are U talking about the Air-box Inlet Air duct piping?

    GPX engine was 10 Bhp up on the standard ZX/ GPZ 600 (75 Bhp) and rated @ 85 Bhp @ 11,000 Rpm! Higher Compression piston and a re-ported head on the inlet side with lighter Inlet valve train.
    The 30 mm Carb's were better @ fuel atomisation n' producing power @ low n' mid range Rpm values thereby giving more a wider power-band n' more usable power throughout the RPM range till 9,000 rpm.
     
  9. COTTONTOP

    COTTONTOP Member

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    Well that is good to know. Being shaft and all that makes it run even better as there’s no lag time between throttle and acceleration like there is with a chain driven bike. My bike has 11:1 compression and is running on 91 octane gas. As far as the snorkel like I said I had to use pods because the original air box was gone.
     
  10. COTTONTOP

    COTTONTOP Member

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  11. Ed

    Ed Active Member

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    The snorkel is the inlet for the airbox and is the most restrictive part of the airbox. It helps keep a constant maximum airflow rate throughout the service life of the air filter. When running pods, the AFR gets richer as the filter gets dirty, especially if they are small.
     
  12. Trojan441

    Trojan441 Well-Known Member

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    I thought that is what U meant , funny how English usage varies across the pond! The most important book on Motorcycles i ever bought was some was some 35 years ago , by the Australian P.E. Irving of the Institute of Mechanical Engineers, (Phil' Irving), who worked amogst other places @ Velocette & famously Vincent where he developed the mighty Series A & then post-War Series B Vincent "V" Twin from 2 x 500 cc singles. It's called "Motorcycle Engineering" published in 1960, when the motorcycle was about 60 years old! And importantly it has the relevant Math's in it; ISBN 0-85113-075-5 first published by Clymer & then by Speedsport Motobooks, (My copy)! I also have an Electronic copy of his book, Tuning for Speed!

    For instance he tells you that in order to get fuel atomisation & subsequent vapourisation of the fuel for spark ignition, a considerable air velocity is required and maximum torque of an engine is usually around 300 feet per second through a choke.
    The "mean" (average,) air velocity which in practice hardly ever exists in reality through engine pulses as you go through say the Four-Stroke cycle is determined by this equation/expression:
    You multiply the "mean" piton speed by D2/d2 where D is the diameter of the cylinder bore & d is the diameter of the Inlet passage, (2 in this case is the power 2, otherwise known as the the "Square root").
    S is the Stroke and if working it out in Imperial Feet, then all measurements have to be in the "Sacred" Inch/inches!

    V = S X2 X rpm X D2
    12 60 d2 the bottom line divides into the top line values , so for a 500 cc Single a 300 feet/Second mean air velocity, through a 1" & an 1/8 , (1"1/8 ) bore choke carburettor @ 3,500 rpm! Maximum torque of this type of engine for the road is developed @ a around a theoretical 3,500 rpm. Maximum power is attained @ a much higher rpm/ (Road speed) because the drop-off in torque through the choke & due to air-restriction is slower than the gain in power by the increased rotational speed, (rpm) of the engine!

    If you have Nortons as I have and a project to put a car engine 930 cc all alloy tuned Rootes 4 cylinder engine, in a Norton Featherbed, you can have fun with the MATH as you Americans say, tuning your engines. Alas most Japanese machines are already in a high state of tune & little can be done to improve on this, in fact most people that fiddle with them make them worse rather than better!
     
  13. Trojan441

    Trojan441 Well-Known Member

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    Sorry " = the square of the integer not the square root which is a divisable sum!
     
  14. Ed

    Ed Active Member

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    Thanks for the info. The "choke" you mention for best atomization is after the airbox and the snorkel is before the box. It's there for sound deadening, filter life and in some cases, limiting HP. The snorkel does help tractibility at low speeds/light throttle. I'd love to have some of those old books. That kind of info just isn't easy to come across these days.

    Formula SAE uses 600cc inline motorcycle engines for cart racing. One of the rules is they have to breath thru a single 20mm diameter restristion which keeps them at a safe, competitive (racing against twins, etc.) speed and teaches the students how to get power thru other means. Amazingly, they still put out 75 HP. Increasing airbox volume adds power up to a certain point and then the gains slowly diminish. Helmholtz resonance tuning isn't considered because it only works at a specific RPM which is useless unless you have a really bad dead spot.
     
  15. Trojan441

    Trojan441 Well-Known Member

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    Choke equals the actual carburettor choke bore.
    V = S X 2 rpm D2
    12 60 d2
    For my Four-stroke SOHC 930 cc Imp engine i have a Weber Single barrel twin chokee DCD 28/36. The development & history of Weber carburettors is worth a read too. Eduardo Weber was a true genius in Carburettor design he was assassinated in Italy in 1945 by the Far Left for supporting the Facista, his body has never been found! What a loss to the motoring world!

    With pods there is the problem of extreme shortening of the Inlet tract fine for proper racing, but not so good for a flexible engine & tractability!
     
  16. Trojan441

    Trojan441 Well-Known Member

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    12 is under S X 2; 60 under rpm & d2 under D2. I type it right post it and the configuration alters!
     
  17. COTTONTOP

    COTTONTOP Member

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    Hey guys that is exactly what I did with the 2 inch tubular spacers on my 32mm carbs. When you can balance the air intake with a slightly longer runner before the carbs and with the bigger 32mm carbs and jetting, I found that I got excellent acceleration, idling and great performance.
     
  18. Trojan441

    Trojan441 Well-Known Member

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    You got pictures there boy?
     
  19. Ed

    Ed Active Member

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    Something I'd like to do is keep the forward plenum but remove the filter housing and add two huge filters directly to the pipes that connect the two. The foam filter and snorkel which are the main restrictions can be eliminated without changing stock flow characteristics at the carb mouth. I think the battery box is part of the filter housing so some re-engineering might be necessary.
     
  20. Trojan441

    Trojan441 Well-Known Member

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    Or find a later motorcycle air-box you can modify!
     

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