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Help Suzuki Bandit exhaust headers

Discussion in 'Suzuki 250cc In-line 4's' started by Anthony Cole, Jul 16, 2022.

  1. Anthony Cole

    Anthony Cole Active Member

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    Hi all, have started doing some more work on the little Bandit, thinking of a VicRoads permit for some test rides and maybe as far as my local bike tech for RWC, attending to a few things first to make sure the bike is thoroughly RWC and looking respectable, I took the headers off this afternoon, noticed some removable plugs in each pipe near the connector clamps for each cylinder, M6 allen key, could they be used for inserting Lamda probes for the initial factory tuning, what are they for?
    Tony:confused:
     
    Last edited: Jul 21, 2022
  2. amct77

    amct77 the one that got away......

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    If you can help us to know which version of bandit you have.
    But to keep it simple, no bandit 250 have a lambda sensor or fuel injection.
    These gj74a and gj77a models (can be seen on the steering neck vin), have a cdi not a ecu; so good old fashion carbs to work on.
     
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  3. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Usually they are for inserting some form of factory test tool, which will be described in the workshop manual.
     
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  4. Anthony Cole

    Anthony Cole Active Member

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    My Bandit is a gj74a (GSF250P) with four vacuum lifter carbs and CDI ignition, my only thoughts were that the holes might be used for temporary insertion of an O2 probe during initial factory adjustment of the pilot jet circuit on each of the carburettors, (emissions compliance)
    I would love to find a workshop manual that is specific to the Bandit, the best I have done so far is find one for the Across which is really a quite different bike, If anyone could direct me to a 250 Bandit workshop manual download it would be appreciated.

    Tony:)
     
    Last edited: Jul 21, 2022
  5. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Last edited: Jul 22, 2022
  6. amct77

    amct77 the one that got away......

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    I have the gj74a workshop manual scanned and in pdf, but I'm having trouble uploading to resources. And it's still in Japanese.
     
  7. Anthony Cole

    Anthony Cole Active Member

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    Thank you for the links, just wondering now if the gJ74a model was uniquely for he Japanese market hence only Japanese language documentation available, I have talked with a Suzuki dealer here and he remembers selling the VVT version, (red cam cover) at his shop in Mont Albert, will have to ask him if he ever had any english language documentation, anyway, I'll struggle on here, get what I can from my Across man, Its great catching up with a few folk that have own these 250s though.
    Tony
     
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  8. Simon

    Simon Well-Known Member Premium Member Contributing Member

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    You are correct that the holes in each header are direct fitment from the factory and are indeed used for setting up the carbs properly. You will note that there is one in each of the headers giving accurate mixture (lambda or afr) for each specific cylinder and carb. On the bandit they are on the inner bend of the header pipes, and also in the same location on the suzuki 250 cobra (model gj73a). On the very similar gsxr 250 (gj73a) they are located on the inner lower part of the downpipes after the SPES (suzuki power up exhaust system) chambers which suzuki copied off yoshimura . I'm not sure what your ideal settings are as your exhaust wont have these chambers and the engine while basically the same has a slightly different state of tune, but for the gsxr 250 (gj73a) I have a full set of AFR data as to be expected on a freshly rebuilt 180psi + compression (factory tolerances) engine which gives best AFR settings for either power or rideability. The data has all been aquired using an Innovate LM2 wideband using two channel input, cylinder by cylinder (inner cylinders then outer cylinders) one at a time. The inner and outer carbs on the gsxr run different size main jets from the factory though i'm unsure if this is the same on the bandit. If you go down this route I'd first get a full Litetek seal kit (maelstrom) to make sure the carbs seal properly (if not you'll be chasing your tail as the results will differ every time you do another run) and once the seals are as they should be purchase the carb tuning kit from keyster ■ FS-5562NU/S GSX-R250R GJ73A 1989-1993 Carburetor Repair Kit Keyster Fuel Conditioning Kit 3 / 【Buyee】 "Buyee" Japanese Proxy Service | Buy from Japan! bot-online

    It will have standard and richer/leaner needles and a full assortment of jets, basically all you will need to tune it properly cylinder by cylinder, the LM2 Innovate can be picked up for around £300 here in the uk though i'm unsure of its cost in Aus. You wont be able to set up anything other than pilot/idle mixture for each cylinder stationery, unless you can monitor the afr on the road under load as the afr changes hugely - hence the need for the LM2.

    Hope this helps and good luck,

    Cheers from the uk,

    Si
     
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  9. Anthony Cole

    Anthony Cole Active Member

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    Hi Simon, my Bandit coincidentally, is running a GJ73a ignition at present, the original igniter box was weak, kiffsta helped me out with a trigger wheel and CDI from a GSXR250, I will eventually get around to replacing the power transistors and capacitors in the old CDI and get it back in the bike but the engine still seems to run fine with the unit a with different advance curve. I'm at present just getting the little bike to a state where I can safely and legally take it out on the road and see how goes. Just been looking around the Innovate site, lots of very useful kit for tuning bikes, you have sent me a lot of good information to help me with the Bandit, thank you.
    Cheers Tony
     
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