Kawasaki ZZR 600 discussion forum:Needle shim for mid-range improvement...a free mod. |
Needle shim for mid-range improvement...a free mod. |
castle1925 said 2009-07-05 11:37 |
After re-shimming my Yamaha FZ1 and experiencing much better midrange torque, I tried it on my ZZR600. It made a substantial difference in overall performance. The bike feels like it gained 75cc. Everything else on my bike is stock. (Note: If you want to maintain low-end response, do not install aftermarket slip-ons!) The re-shimming job is not excruciating. It took me about an hour and a half. Basically, you are going into the tops of your carbs, removing the needle assembly and moving a washer shim from the top of the needle to the bottom side. You´ll need a 10mm socket with a medium extension, and preferable a T-handle, needle-nose pliers, a phillips screwdriver, and a right-angle phillips ratchet screwdriver. I got the latter at Harbor Freight. 1) Unlock the rear seat and lay aside. 2) Use a 10mm socket to remove the clip that holds the front seat and set aside. 3) Remove the tank bolts (sorry, I´ve forgotten which wrench is required), turn off the gas, pull the gas tube off, and remove the tank. 4) Use a 10mm socket (a T-handle helps) to remove all the airbox bolts. 5) The top of the air box will need a little coaxing off the air inlet tubes. Set aside. 6) The carb tops are now exposed. (Don´t worry about intervening hoses and cables, you´ll be able to work around them). 7) Using your phillips screwdrivers, remove the four screws from the left-most carb top. Pull out the throttle spring and set it and the top aside. 8) Gently pinch and pull on the rubber diaphram to remove it along with the slide and needle. 9) Working on a clean, well lit surface, use your needle-nose pliers to pull the plastic needle holder from inside the slide assembly. A small spring will come out along with the needle...don´t let the spring get away! 10) There are two small washers threaded on the top side of the needle. Remove the top washer and thread it back onto the needle from the underside. That will cause the needle to sit higher, allowing more gas-to-air mixture at midrange throttle. 11) Replace the spring onto the tit under the needle holder. Keep the needle tip elevated so the washer and spring stay on the needle while you re-insert it back into the slide assembly. This sounds hard but will be obvious. 12) When you have the needle assembly pushed all the way back into the slide assembly, use a fair amount of thumb pressure to lock it in. You´ll hear a click. The first time you do this, you probably won´t hear the click because you were timid and didn´t press hard enough! 13) After you hear the click, you can push-test the needle up some just to verify the needle spring is doing its job. The needle may wobble a little off center, but that´s only because it´s out of the carb. 12) Slide the big throttle spring into the carb body, then replace the slide assembly. It can only go in one way, but you will need eyeball the jet while guiding the needle into it as you lower the slide. You´ll need to be seated or have you head lowered and tilted sideways behind the carb to gain the proper view. 13) Once the needle is back \ |
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