Monday, June 20, 2011

Tuning the Suzuki Bandit 1250

This is a topic that comes up in bits and pieces all over the Net, so it's worth recording my experiences in one place.  This is what worked for me.  If you aren't confident, competent or know what you are up to, don't do this.  Do it at your own risk.

ADJUSTING THE THROTTLE POSITION SENSOR (TPS)

Firstly, it's worth getting some baseline figures on the Bandit's injection system.  Purchasing a dealer mode switch part number  enables you to check the fault codes and the throttle position sensor (TPS) setting.  It should be -C00 with the cursor in the middle position as shown below.  If the cursor is elsewhere (i.e. up top or down low), the TPS is slightly out of adjustment.

Any other codes, check the manual.



To adjust it, you will need the bike in dealer mode.  The connector is under the right hand side cover with a white dust cover on it.


Connect the switch (you can short the plug with a paper clip to achieve the same effect), turn on the bike and turn the switch "on".  If all is well you will get -C00.  If the cursor is anywhere else, find the TPS, which is on the left hand throttle body, and slightly loosen the two security Torx bits, which are type T20H with the hole in the middle.  Do not remove them, and do not remove the TPS from the throttle body.



You will see the cursor move with even undoing it, so take time and a little patience to get the cursor in the right place.  DO NOT overtighten it, because you may crack the housing.  In theory you should adjust it with the throttle stop screw between the throttle bodies, but it's buried deep and I don't know anyone who has managed to get to it.  Is it critical?  Suzuki say good is C00 and don't mention the cursor.

BALANCING THE THROTTLE BODIES


Do this after you have replaced the plugs and cleaned/replaced the air filter.  I don't plan to list those steps here, as if you don't know how to do that. you shouldn't be messing with this.  Balancing the throttle bodies will give smoother idle, smoother low speed running and reduced surging.

To do this, you will need a 4 carb balancer.  I use the Morgan Carbtune Pro:


There are various schools of thought on balancing, but I used the Suzuki method listed in the service manual as "Use of Mode Select Switch".

You put the bike on the main stand, and remove the tank and prop it up so you can access the throttle bodies with the fuel hose and fuel pump still connected.  I use a Metrick metal (www.metrickmetal.com) tank prop:


  Connect the dealer mode switch, and run the bike until it is warm.  Wait until the fan kicks in (don't adjust anything if the fan is running though).  The dealer mode switch automatically sets the bike in synchronisation mode.  (Some people don't use the switch and apply vacuum to the IAP valve, but I don't think it's necessary).

Stop the engine and attach the Carbtune lines to the vacuum ports on the manifolds.  The number 1 line is shown marked below - pull it off an replace it with the Carbtune line and repeat for the other three.

Make sure the mode switch is"on" and run it.  Check the 4 readings are the same and use number 2 cylinder as the base reference.  Getting the 4 columns even is the aim.  The speedo will show "C13" which means the IAP isn't getting vacuum because it's disconnected from the manifolds.  Ignore that

The levels are adjusted with the air screws on the throttle bodies.  The air screw by the number one injector is shown below.  Turning it clockwise makes the column rise.  Don't unscrew them too much - small turns are all that are needed.

Give the throttle a "blip" when you think it's right, as you may have to fiddle a bit.

If you get it right, smooth running results.  If your bike idles poorly afterwards, a common fault is due to leaving the vacuum lines disconnected from the IAP sensor.  Any vacuum leak means she won't run.

19 comments:

  1. Thanks for the info.

    ReplyDelete
  2. Just have to buy the Morgan Carbtune .

    @67500 km I'll give it a try
    Greatings from Holland
    Lampie GSX650F K8

    ReplyDelete
  3. Why "number 2 cylinder as the base reference"?

    ReplyDelete
  4. Recoomended by Dale Walker (www.holeshot.com). He's an expert on tuning these, so I follow his advice

    ReplyDelete
  5. Brilliant info. I've checked the fault codes and am getting _C00
    Do I need to move the TPS? If so how much by and which way? I'm a little confused.

    ReplyDelete
    Replies
    1. Hi. Ian. Unless the bike is running badly, I really wouldn't bother. From my perspective it's a difference that makes no difference if you know what I mean.

      Delete
  6. I am checking the air screws now. They are all 1 1/4 turns out by closed. What is the Factory setting for #2 air screw?

    ReplyDelete
  7. There's no specified amount. Leave it at 1.25 turns and adjust the others to that vacuum reading

    ReplyDelete
  8. Hey and thanks for the nice tutorial!

    By mistake we first loose the STP sensor (right to the TPS). How can we get it back to the correct position? We just fastened it the way we think it was before.

    Thank you and greetings from Germany!

    ReplyDelete
  9. Hello,

    The skrew in the middle, how many turns is the Factory Settings?

    Thanks

    ReplyDelete
  10. Pak Suzuki introduced some of the heavy bikes with new and advanced features Bandit is one of them.
    Suzuki Bandit in Pakistan

    ReplyDelete

  11. It’s actually a great and also handy section of details. I am just fulfilled that you simply contributed this helpful info along with us.. Be sure to keep us knowledgeable similar to this. Thank you for expressing.
    car removal brisbane
    cars removal brisbane

    ReplyDelete
  12. The instructional exercise is exceptionally useful for a beginner like me, incidentally on the off chance that you might have given an instructional exercise on making a free site, it would have been extremely useful for amateurs like me.
    Ezy Car Removal provide cash for your old cars with free removal doorstep service.
    Old autos removal Gold Coast
    Junk Vehicle Removal Melbourne
    Unwanted Car Removals Brisbane

    ReplyDelete
  13. A very helpful article with detailed instructions that even a novice can easily understand. Thanks for revealing such knowledge to us. It's impressive to see your commitment to this line of work and I wish you all the best!
    Cash for Cars Adelaide
    Cash for Cars Glenelg
    Free Car Removal

    ReplyDelete
  14. Such a helpful article that allows even novice business owners the chance to understand better strategies for success! I really like your dedication toward this line of work and I hope we'll all be able to benefit from whatever knowledge you have.
    Cash for Brisbane
    Cash for Cars Caboolture
    Junk Car Removal

    ReplyDelete
  15. This is a great article with easy-to-follow instructions. Thank you for sharing your knowledge with us. It's impressive to see your dedication to this line of work, and I wish you all the best! Please check out Car Removals Adelaide and Cash for Junk Cars Adelaide services.

    ReplyDelete
  16. Thank you for sharing your helpful thoughts with us! I'm excited to learn more from future posts. This is a very helpful post. If you need to sell an old or unwanted car, please check out our Car Removal Brisbane, Top Cash for Cars Brisbane, Cash for Cars Caboolture, and Gold Coast Car Removals services. I will be able to help you get the best price for your car. Thanks for reading!

    ReplyDelete
  17. Thank you for sharing this valuable knowledge with us. This post contains a lot of useful information. Keep up the wonderful work, and may God bless you. Check out the Cash for Cars Adelaide, Car Removals Adelaide, Old Car Removals, and 4x4 Truck Removal Adelaide services if you need to get rid of an old, trash, or unwanted vehicle while also earning some cash.

    ReplyDelete