, hopefully will help someone out in the future. Its about PHBH carbs but the principle is the same for other carbs I would of thought.How to check your jetting using the choke test:
""Then take this to a quiet layby/empty business/science park where you will not upset anyone by revving, then, with the bike on the stand, rev the bike to the 1/4 throttle mark. Does it progress off tickover ok? When the motor is held at 1/4 and you turn the choke on, does it immediately bog (hopefully) or does it continue to run (indicates too weak or that choke isn't working!). Adjust as necessary.
Then do the same at 1/2 throttle. The bogging will not be as dramatic at the increased revs but it should still bog pretty dramatically, which indicates that the extra fuel supplied by the choke system has made it too rich. Flicking the choke off again should make it run better. The diameter of needle and atomiser will affect everything below and up to half throttle. Remember that the X2, X13, X7 needles all have the same shaft diameter and tip diameter, they only differ by taper length, meaning that the X2 gets richer sooner and the X7 later, they should all be the same up until the taper comes in.
Do the same at 3/4 and note that the bogging will be less at the higher revs, although it should be evident. The motor may continue to run but the tone will be deeper and you may hear/feel it miss a beat as you turn the choke on. If it doesn't make any difference or runs better then you need to richen it up, by lowering clip position or perhaps by fitting richer needle (X13), then test clip positions again until you are happy that putting on the choke does have a slightly negative affect on the running of the motor.
Then you can do the same for full throttle, which will rev like a beast on the stand and may scare you! You'll not want to do this for long but you can also do this test on the road. Indeed, you'll check all of these positions on a quiet straight road, in good conditions too, by riding at the throttle position marked and reaching down and flicking on the choke, which at low speeds will cause the bike to bog heavily, bogging less the further up the range you go. By the time you are testing full throttle, the choke should have little affect but may just cause the motor to miss a beat and then continue to run ok. What you don't want at full throttle is for it to have zero affect or run better with the choke on.
Another good test to do in the quiet layby/business park is to remove the main jet completely and (bike on stand) work your way slowly up the positions, then note where the motor bog when you come onto the main jet (approx. 3/4). If it bogs out at half throttle then it set too rich on needle/clip, if it runs clean beyond 3/4 then the needle + clip is too weak.!"
