I did a search and found some info but I want to be clear before I start my final adjustments. I started up my V-Force today after installing a second snorkle on my air box, shimming the stock carb needles (.020) and upping my main jets to 152/155. She started up OK but as it was warming up if I were to tap the throttle just a bit the motor would continue to "race" for 5 to 8 seconds AFTER letting go of the throttle.....no back firing. It was also running a bit rough. I shut it down and checked the two fuel/air screws (for the first time since I got the quad). I turned both screws clockwise untill they stopped and found the front carb screw had only been backed out one turn from the factory and the back carb screw only 3/4 of a turn. Is that way to little or am I off base. I just want to make sure but with my current set up (ProCircuit dual exhaust, K&N filter, Dual snorkles, stock carb needles shimmed .020, and 152/155 main jets) shouldn't I have the carb fuel/air screws backed out more like 2 1/2 to 3 turns? Also should the front carb screw adjustment be different than the rear carb? I couldn't find the answer to this last question by doing a search. ANY input would be great! Thanks, Mark.

 

I have never figured out why people are still counting turns on their idle mixture screws (fudge method). The idle mixture needs to be adjusted, not fudged.

Use the 1/4 turn past the fastest idle method. Turn one of them way in (so that engine slow a lot, then slowly back it out until you just reach the fastest idle. Then go 1/4 past that. Then do it again on the second screw. If the idle speed is too fast afterwards turn the speed down too.

With all the mods we do, and all the different elevations and different ways of spraying air filter oil on, we should never just turn the screws a certain number. They should always be adjusted. Now, if 1/4 still backfires, maybe try more. But they should be adjusted, not just turned.

 

Try 2 1/4 on each pilot screw. I am at 2 now and I have a slight burble upon deccel from WOT. I am going to 2 1/4 . Also did you manually move the slides all the way open after installing the shims, to check for spring bind?

 

nyroc, I believe counting screw turns after doing mods on your ride is ONLY to get into the "ball park". I don't believe anyone thinks that the 2.5 turns is a "magic" end all setting but I see what your saying.....I'm glad I posted the question. I'll follow your method tomorrow. Thanks!

Pistonman, thanks for the input.....you confirmed my thoughts. I did check that the slides moved their full range without binding before putting things back together, thanks.

 

Yes, I do the count for ballpark- as you would on a Holley- to get running. I bet you could set them with a vacuum guage.

 

the ? is where to hook up the vacum gauge. i tryed to hook it into the intake's but its to erratic. i thought i could do this like a car or truck motor. their has to be a better way than the ear method. if not i will do it the only way we can.

_____________________
02 650p
nyroc muffler
napa #7335
145f/147.5r jets
needles- .033
dynatek cdi
epi black
700p drive spring
warn 2000
plow

 

You could get one of those air/fuel ratio sensors and plug into the exhaust.

You could get thromocouples and put them in the exhaust flow right in each exhaust port.

But, you don't need do all than fancy smancy stuff just to set your idle mixture. The ear method is good enough for the idle mixture. Just take the time to do it right and you will have a great idle.

when I did that, but found that I was still too rich after having the idle bog down in streams and puddles. At that point I turned both in 1/8 turn. The point is that the ear method is far superior to just guessing turns. I got each cylinder set to the mixture it needs. Whereas the fudge method does not really get each cylinder where it needs to be.

 

jetting
This site has a list of symptoms and how to correct.

 

Isn't that, when you have a backfire through the exhaust when letting off throttle it is caused by a lean idle circuit? If so then wouldn't you need to screw in the mixture screws to richen it up?

 

nyroc & hondab: Both sites very helpful.