stock carb question

[64xracer]

Just a quick question...if you were way too rich on the main jet could that make it run bad from idle to half too?

[yamaha04]

well if you take a look at this post it seems to me then main jet really starts working at around 1/2 the WO throtle. it looks to me you could mess around with your ar/fuel screw and see if it changes your problem

http://www.bansheehq.com/forums/index.php?showtopic=47286

[64xracer]

Well I had it running good with 380 mains and the plug chop looked to be a little lean so I installed 390's and it would not idle as well and had a hell of a bog off idle to half. From half to WOT it was great. So I tried moving the needle...top, middle, bottom...no difference same with the air screw. I took the carbs completely apart and cleaned them 3 times, I even switched to a different set of clean carbs with same jetting, I just could'nt figure it out so I put the 380's back in and now it runs awesome again..?? WTF

[mpbanshee]

380's!!! Holy crap! My guess is you have an air leak somewhere, or something is wrong in your carbs. Take them apart, clean all jets and passages, and put them back together CAREFULLY. Make sure everything is installed correctly. Then tighten up all clamps and check for air leaks. Something is not right...

[64xracer]

No air leaks, carbs are clean. I have 3 shees in my shop right now all pretty much set up the same, one has 410 mains and runs perfect, another has 370's and the last one with 380's. All have K&N pod filters, ported to 190 ex and 126.8 transfers, +4 timing, and t-5 pipes. The only difference is the compression between them. Temp is 55 and elevation is 1500 or so.

[Duner440]

Your jets are waaayyy too big. I think you have another problem.

[baddsheee]

Your jets are waaayyy too big. I think you have another problem.

 

Your jets are huge. I have a dune port and pods. I am running 340 when I go to sea level. I didn't even know they went that high to 410

[64xracer]

I did forget to mention that they are bored stock carbs (28mm) I took starting fluid and sprayed around the carb boots to check for leaks and nothing there. The shee that has 410's has been running that way for 3 years without any problems...well except when it gets to 100 degrees or more then we lean it down a bit. The plug chop looks excellent, and yeah I am doing it correctly. Warm engine on old plugs, put in new plugs, wot till 6th, kill engine and coast to a stop, change out plugs with old ones and the cut away on the plugs. Nice choc brown ring. I wonder why these 3 shee's have such big mains? Any ideas? Just a thought...bored stock carbs need bigger jets because signal is'nt as good as when it was stock so you have to put a bigger jet in to compensate for it. I don't know what do ya think?

[BansheeDan]

I did forget to mention that they are bored stock carbs (28mm) I took starting fluid and sprayed around the carb boots to check for leaks and nothing there. The shee that has 410's has been running that way for 3 years without any problems...well except when it gets to 100 degrees or more then we lean it down a bit. The plug chop looks excellent, and yeah I am doing it correctly. Warm engine on old plugs, put in new plugs, wot till 6th, kill engine and coast to a stop, change out plugs with old ones and the cut away on the plugs. Nice choc brown ring. I wonder why these 3 shee's have such big mains? Any ideas? Just a thought...bored stock carbs need bigger jets because signal is'nt as good as when it was stock so you have to put a bigger jet in to compensate for it. I don't know what do ya think?

 

 

 

im at 850 ft above sea level and i run 280's in stock carbs with a pro flow setup and k&n in the airbox

.040 overbore and .040 off the stock head +4 timing and a very light port job by a&s racing

and Dan himself jetted and tuned my bike

 

i agree with the others

someting is up if youre having to run that big of jet

 

 

Dan

Edited April 18, 2007 by BansheeDan