I have a 99 big bear YFM350 with a Mikuni 34 carb.
I am rejetting it in preparation of a new Pro Circuit pipe.
I have an airbox mod already.
I am going up 2 steps on the main jet from 125 to 130 and one step up on the pilot jet to a 45 from 42.5.
Now the pilot screw is on the inside of the carb and you can only get to it by removing the float bowl unlike some carbs that you can get to it from the outside.
The manual stated that the stock setting is 2 turns.
The pilot screw protrudes into a hole in the throat of the carb which means it regulates air flow.
My question is this...
since it is so hard to adjust it I would like to know how much adjustment it needs to make a noticeable difference.
Stock is 2 turns out,and since I want to richen the mix, should I start at 1 3/4, 1 1/2, or 1 turn?

Orr.. maybe the air flowing past the little hole at a high velocity sucks fuel through past the pilot screw... then backing it out would richen it....

 

every carb i have ever dealt with required the screw to be backed out in order to richen then pilot circuit. man thats a pain in the you know what if you have to remove the bowl in order to adjust your idle screw. i would start at 2.25 turns out. now cruise and let the engine brake for you upon decelleration. if it backfires, you are still lean on your pilot so turn it out a little more and repeat until you have no more backfiring. hope this helps.
another thing you can do is get a warrior carb off of ebay for a decent price, then you have a 36mm, with the ease of adjustability that you say the 34mm doesnt have. it should bolt right on, they share the same motor. after that its just a matter of properly jetting it for your bigbear. good luck!

 

cool.. actually I took a second look at the carb in the light (always helps) and the pilot screw is actually on the OUTSIDE of the bowl.. my bad..
Now I can start at the factory setting of 2 and go to 2-1/4 etc..

thanx..

 

Lots of people make the mistake of thinking the pilot jet is what is backed out 2 turns. All jets are solidly bottomed in their locations, and none are backed out. Everything inside the float bowl is tight.

 

<div class="FTQUOTE"><begin quote>Originally posted by: hondabuster

Lots of people make the mistake of thinking the pilot jet is what is backed out 2 turns. All jets are solidly bottomed in their locations, and none are backed out. Everything inside the float bowl is tight.</end quote></div>

I know that,, I was referring to the pilot screw..