sorry, another jetting isue

1 reply to this topic
  • wedge450

Posted January 23, 2008 - 10:35 PM


Hi, i have done a few search's and can't fix the problem. I bought the bike, it is an 06 and has very low hours, the only thing done to the motor is a twin air filter and a full dr. d pipe and the o-ring mod. the jetting is a 168 main, 3rd clip on the needle and a 48 pilot with 2 turns out on the screw. i am at sea leval to 600 feet and it is about 35-45 degrees right now. It has a bad hesitation from an idle when you crack it realy fast, and when you hold a constent throttle crusing down the road at about 1/4 throttle it kind of miss's a little bit. what can i do to fix the problems?

Thank you.

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  • grayracer513

Posted January 24, 2008 - 07:41 AM


If by "3rd clip" you mean the third groove from the top of the needle, your needle is leaner than stock, and that's at least part of your cruise misfire problem. Try it in 4 or 5.

Frankly, there is no need for an engine to respond to a sudden hard opening of the throttle from closed throttle at idle rpm because that never occurs in actual riding. Efforts to completely cure this problem often end up creating other rideability problems in the process, too. The bike should respond well at all times when you're under way in an appropriate gear, but will never be able to completely stand a full throttle snap from a low idle in neutral. It should be responsive enough that you don't have to tiptoe around the throttle to get it up off an idle without stumbling though, but you have to be reasonable. You have an engine with a very large carb and intake tract for its size, aggressive cam timing, and it's a single cylinder to boot. You can only expect so much.

Getting the jetting right will help, as will going through the accelerator pump timing procedure in the manual. Warmer weather will also help. Sending the carb out to Zip-Ty for their race mod will sharpen the overall performance considerably as well. But you need to learn to "roll" the throttle. This is a technique riders of big 4-strokes had to teach themselves in the days when the bikes had no accelerator pumps at all. The throttle is opened only partially, and is opened farther as fast as the engine can respond to it. Once learned, it becomes completely automatic, and the engine will sound as if it's responding instantly.

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