new fmf pipes and main jet:(

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csrt4

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May 9, 2012
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Figured I would start a new thread since my other one got hijacked..
I know this topic is really beat to death, and I think I have done too much reading on jetting and now I am really confused..
Ok so I got my pipes on today,went to the dealer and they only had 280 and 290 main jets.. they seemed to be a little rich for my setup of stock bore,Fmf pipes,and airboxlid removed.. I did not get to do a plug chop today but installed the 280 to get it running and see how it felt and sounded... I took it for a quick spin and it pulls harder up top but is sluggish and misses in the low/mid range wot, but once it hits the upper rpms it pulls and sounds normal.. could this be a symptom of running too rich??? I know I NEED to plug chop but,just wondering if it could be really rich and the bogging down low at wot is just too much fuel???
 
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See before I put the pipes on today, last week i cleaned the carb real good, and dialed in the air screw to 1½ turns out. As well as adjusted my idle... seemed to be running great till the pipe install and jet...
I am also getting a off throttle knock sound... its only when I go wot and snap the throttle shut...
but if you say I need to adj. The air screw after the install I will give it a try..
 
^^^yes, a little more info would be a big help. ive read somewhere that knock could be a lean issue. prolly the 1 1/2 turns out only. while its idling, turn the air screw out till you get your highest idle point. do it in small jumps like 1/8 or 1/4 turns. give it a sec between to let the engine catch up. most guys say to leave it there once you hit that sweet spot. i turn mine back in 1/8 a turn. just so i know im not on the lean side of things. anyone else got a way to do it???
 
dksix said:
Where is the needle?
Click to expand...
Im not quite sure.. I will try to look at it tomarrow and report back... I am going to say the middle clip thought, as it was completely stock two weeks ago when I bought it..
mjgnslngr said:
^^^yes, a little more info would be a big help. ive read somewhere that knock could be a lean issue. prolly the 1 1/2 turns out only. while its idling, turn the air screw out till you get your highest idle point. do it in small jumps like 1/8 or 1/4 turns. give it a sec between to let the engine catch up. most guys say to leave it there once you hit that sweet spot. i turn mine back in 1/8 a turn. just so i know im not on the lean side of things. anyone else got a way to do it???
Click to expand...
See this is the other part, when I first bought it it wouldn't idle but ran well, I cleaned the carb, then tightened the air screw clockwise, then 1½ turns out, and then messed with the idle screw till it was idling.. after it would completely warm up and riding it hard the revs would climb to 2000ish rpms , if I let the clutch out a tad and and bring it back the idle drops and holds at the normal idle...
I have not done an air leak test yet but is also on the agenda...
however I have been told to pull the choke, if the idle rises you have an air leak.. if it stalls then no airleak... when I pull the choke it dies, so it lead ne to believe there isn't an airleak...
 
that choke trick isnt 100%. the tors could be screwing up your idle too. you really gotta do a leak test. thats the best way to eliminate Alot of questions and save your engine from a meltdown!
 
yea i have read a ton of how to's and vids on tors elimination, next on my to-do list to eliminate a possible issue... my only question with it is, if you leave the tors assembly on the carb and delete the wires can i still use the idle adjust screw on the tors unit????
 
csrt4 said:
yea i have read a ton of how to's and vids on tors elimination, next on my to-do list to eliminate a possible issue... my only question with it is, if you leave the tors assembly on the carb and delete the wires can i still use the idle adjust screw on the tors unit????
Click to expand...

yup! after you disconnect the wires to it, it just becomes a big hoggin idle adjusting screw. most guys dont even bother with the tors elimination cap n idle screw deal for 50 bucks. save that dough for a bigger carb when the time comes...
 
Alright thanks man..appreciate the help...
So... first thing I am going to do is delete my tors
Second is check which notch my needle is on
Third adj. air screw and idle screw
Forth plug chop
If all fails it will be leak down test..(even though I don't think I have one) lol
Thanks again peeps, will post back with my findings...
 
csrt4 said:
I cleaned the carb, then tightened the air screw clockwise, then 1½ turns out, and then messed with the idle screw till it was idling.. after it would completely warm up and riding it hard the revs would climb to 2000ish rpms , if I let the clutch out a tad and and bring it back the idle drops and holds at the normal idle...
Click to expand...

Sorry to dissapoint you but you have been adjusting the idle incorrectly. Your low range throttle responses will be all over the place.

The correct way to adjust idle.

Start with air screw 1.5 turns out.

Set idle screw so that it has some kind of idle.

Warm up motor and then set idle screw for a fast idle.

Adjust air screw either way to get the fastest idle.

Adjust air screw a little at a time leaving 10 secs to allow the motor to respond.

Re adjust idle screw for desired idle .

The first thing on the list of things to do should be a leak down test, if there is any sort leak, you will never get the jetting right.
 
^^^ Agree 100%. I see one of your original questions got ignored, you asked if in the mid range it acts sluggish, like it's spitting and sputtering but then it will take off like a bat out of hell...not your exact words, but that is the jist right? Okay, that is indeed rich, and while it is spitting and sputtering at WOT it is cleaning itself out. If you eased into WOT or feathered the throttle a bit, it wouldn't react that way so much. I have been having this same issue trying to jet my carb. What I would do, is when it started spitting and sputtering, I would pin it for a bit and then back off and stop, pull the plug and look at it to see what was going on...sure enough, it was flooded every time. This just means your main is actually a bit on the big side and or your needle isn't set correctly for the main. I have a FMF Gold Series Fatty Pipe, Turbine Core II w/Spark Arrestor Silencer, a 28mm Mikuni, stock Reeds, Stock Filter and air box with the lid. I was told to start around a 270 main once I figured out my pilot, and I have to completely lean out my needle to get it to run thru 3/4 throttle. I plug chopped at 1/2 and 3/4 throttle with that setting and the plug looked brand new...SUPER LEAN. I'm going to be dropping my main down to a 260 and starting at mid clip with my needle again. I'm pretty sure that will have fixed my problem. Keep us posted on your situation.
 
Blaaster said:
Sorry to dissapoint you but you have been adjusting the idle incorrectly. Your low range throttle responses will be all over the place.

The correct way to adjust idle.

Start with air screw 1.5 turns out.

Set idle screw so that it has some kind of idle.

Warm up motor and then set idle screw for a fast idle.

Adjust air screw either way to get the fastest idle.

Adjust air screw a little at a time leaving 10 secs to allow the motor to respond.

Re adjust idle screw for desired idle .

The first thing on the list of things to do should be a leak down test, if there is any sort leak, you will never get the jetting right.
Click to expand...

No dissapointment as I am not familiar with carbs..more of a fuel injection guy... I will give your idle settings a try tomarrow..
Will the idle setting you described also set my part throttle fueling via air screw???
 
csrt4 said:
No dissapointment as I am not familiar with carbs..more of a fuel injection guy... I will give your idle settings a try tomarrow..
Will the idle setting you described also set my part throttle fueling via air screw???
Click to expand...

No man, air screw is only for idling and determining if you have the right pilot. If you high idle over 3 turns out, you need the next size larger pilot. If you high idle under 1-1/2 turns, you need a smaller pilot. If you high idle doesn't happen, but it picks up idling as you unscrew it, go to the next size pilot and see if you get the high idle. Once you get the first point of highest idle, kill the engine and screw the air screw back in to count how many turns out it is. If you are with in 1-1/2 and 3, turn it back to the spot, fire it up again, back out your idle screw so that it still is elevating the slide, then readjust your air screw again to get the smooth idle. Your throttling issues, they are controlled by you needle and main...and slide, but don't worry about that, you should be able to dial it in without worrying about that.
 
Surfrjag said:
turn your air screw out till it clears up. dont go past 3 turns
Click to expand...

^^^this^^^ is what confused me and thought that the air screw controlled the part throttle..
part of the reason for me picking up this blaster was so i could learn to tune a carb.. if this thing had fuel and ignition maps i would be all over it...lol

i want to get this idle issue down first, then work on jetting it in.. so from what you are saying the bogging low/mid wot is from to rich of a jet and the jet and needle are the only things to effect that???
Also, tomarrow i will be ordering a leak tester from slick.. but i just think my carb is tuned all out of whack, as it ran fine in stock form, minus the idle issue...

thanks guys its greatly appreciated for your help with my not so knowledgeable carb tuning...lol
 
it will have SOME effect on part throttle. this is why your going to have to mess with it and see how it effects your setup. if it bogs when you blip the throttle (i consider this to be part thorttle) then its probobly rich. then you would want to screw it out some and try again. hope this helps.
your innitial question i thought was that your main jet was causing this issue and in your case i dont think it is.
 
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