I have been doing too much reading about jetting here lately.....I notice some of you have or have recommended changing the pilot jet when jetting a quad. I will be the first to admit I am a newb when it comes to jetting, but I have a mechanical background and I like to understand how things work (such as the different circuits of a carburetor and how changes effect those circuits).


Anyhow, I was wondering how changing the pilot jet could be used in jetting a quad and ran upon this from the DJ website:

PILOT CIRCUIT:

This controls 100% of the engine idle and 25% of the transition onto the needle. Dynojet has found that the engine will idle with the standard pilot jet, with or without the air-box and with the slides and needles removed from the carburetors; therefore we never change the pilot jet. Doing so is proof that you are not using the other circuits correctly. Idle and off idle is controlled by the mixture screws and the float level which have the most positive effect below 4000 R.P.M. On some models the pilot air jet is changed to provide optimum fuel economy. Correct balancing of the carburetors also ensures a smooth idle.


So....what is the answer about changing the pilot jet?

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Thats the most idiotic thing I've ever read! How could the engine idle with the slide removed?If it would run at all it would be running beyond wide open,not idleing!I believe there is a definite gap that can show up between the idle and where the needle starts to take over.Changing the pilot jet can be a useful tuning tool.

 

A good rule of thumb is to up the pilot if you need to go more them 3 turns out on the mixture screws.