HUGE PROBLEM WHILE RUNNING

[ProRider199]

hello, i put my bike back together yesterday and am having problems. this is the 3rd time i have had this problem but always thought it was the mechanic not putting it together right so i did it myself yesterday. ok, at idle she runs fine, then at mid range it pops and backfires a little bit, then top end it runs like a champ. i am so confused on what this could be, i keep thinking the carbs, ignition, timing. i dont know, please help me, any suggestions would be appreciated. i have toomey t5's, mild porting done to the cylinders, stock head, stock carbs. i know i need a jet kit but i put bigger mains just for now. im not riding it, i just want to get it broke in and ready.

 

thank you,

troy

[yamaha04]

lets us know what kinda jets your running whats the sizes and polit sizes. what clip setting are you at on your neddle. also what kinda filter set up do you have. do you have a adjustable timing plate if so whats it set at.

[ProRider199]

lets us know what kinda jets your running whats the sizes and polit sizes. what clip setting are you at on your neddle. also what kinda filter set up do you have. do you have a adjustable timing plate if so whats it set at.

 

i beleive the mains are 320's but i could be wrong, i can check tomorrow. i moved the needles to the 4th from the 3rd posistion and seems to be doing better. yesterday they were on the 5th and ran like shit. everything else is stock. i changed the air/fuel from 2-2.5 out and seemed to do the best at 1.5. i dont have an adjustable timing plate. i was worried that my timing could be off but since i dont have that, thats not a worry right?? o and i have k&n filters coming straight off the carbs (stock carbs by the way). thanks for any help u can provide me, i really appreciate it

 

troy

[yamaha04]

ok so since you said the air/fuel works best at 1.5 then i think you need to go to a smaller main next size down. am i right to say this guys?. sorry im not a jetting guy just though i would ask what you are running so other people could see and help. anyway yeah i think when you turn the air/fuel out and it runs better it means you need to move up a size in main the start allover with the air/fuel. so i would imagin if it runs better that 1.5 then it does at 2.5 then i would say you have to big of a main. and need to move down. but again i hope someone else chimes in. oh yeah what elevation are you at and what kinda compression do you have. also have you cheaked your reeds for cracks. just so you can count thowes things out and single out the problem

[blowit]

ok so since you said the air/fuel works best at 1.5 then i think you need to go to a smaller main next size down. am i right to say this guys?. sorry im not a jetting guy just though i would ask what you are running so other people could see and help. anyway yeah i think when you turn the air/fuel out and it runs better it means you need to move up a size in main the start allover with the air/fuel. so i would imagin if it runs better that 1.5 then it does at 2.5 then i would say you have to big of a main. and need to move down. but again i hope someone else chimes in. oh yeah what elevation are you at and what kinda compression do you have. also have you cheaked your reeds for cracks. just so you can count thowes things out and single out the problem

 

 

 

Actually you have 'er basackwards. The screws you are refering to are called air screws and adjust a fine stream of air bypassing the throttle slide. They primarily affect idle and have an effective range of 0-1/4 throttle. There is zero relativity to the screw and your main jets. DO NOT adjust your mains based on this setting. You are fine with your screws set at 1.5 out and that just indicated your motor is needing a little more fuel on the bottom.

 

The condition your are experiencing sounds like lean pop and I am not sure which way you are going on the needle but if you are lifting the needle and it is getting better, that sounds like the ticket. If it ran fine before and just started this, jetting does not just get off so there is something going on. If not, just keep tuning those needles until you hit the sweet spot. We always refer to the needle positions as needle up or down, not clip position. I don't know why people like to use clip positions, very confusing for our customer.

 

Raise the needle to richen and drop it to lean. Hope that helps

 

Brandon

[badassbanshee479]

toomey makes a needle for the stock carbs, it has a different taper on it and more clip spots. mid range is effected by the needle. I would pick a set of these needles up and try them. Also do a plug chop to see how your bike is running, you may need to go alittle bigger on the main.

 

http://www.toomey.com/html/intake_system_parts1.htm

 

if you scroll down you can buy just the needles right from toomey

[ProRider199]

toomey makes a needle for the stock carbs, it has a different taper on it and more clip spots. mid range is effected by the needle. I would pick a set of these needles up and try them. Also do a plug chop to see how your bike is running, you may need to go alittle bigger on the main.

 

http://www.toomey.com/html/intake_system_parts1.htm

 

if you scroll down you can buy just the needles right from toomey

 

hey guys... thanks so much for all the input. i bought a jet kit, it will be here today and ill install them today. ill let u know what happens from there. o yea, it was running lean, i moved the needle up a position and the mid range was almost perfect. i never had these carbs right from the beginning, actually neither did the dealership when i bought it. thats probably y i go through top ends so damn fast. ill keep u all posted on what happends next :thumbsup: