waterbug89

alright guys got my air box today got it on right away wow what a difference all the way up to 4700 to 5000 rpm then i get a bad stutter never had it before. I did a search because i remember seeing a thread about a hick up about them rpms but every one said it was because the air filter being a k&n, to much air but remember i have been with out a top since i owned the bike and no problems like that before the only thing the bike did before with no lid was lacked some on the bottom end like when it was at idle and you cracked the throttle it stumbled about 2000 and up now i got a crisp throttle, any help would be great

8541Hawk

What is your jetting set up?

waterbug89

stock front 175 rear 178 slow 45 im in colorado

waterbug89

alttitude 5280 here in colorado

waterbug89

as far as i know the only mods that would affect jetting are the k&n and a set of d&d pipes

waterbug89

also if i remember right when i cleaned the carbs out they had a clip on the needles this is my first bike so these carbs are new to me i am used to the smaller kehins and mikunis that are on my skis, i guess what i dont understand is the bike runs great except that one dead spot

8541Hawk

Sounds like you are dealing with altitude. You might want to try the "High Altitude" settings which is dropping the mains down 1 size, so you would need to pick up a 172 jet.

waterbug89

i would have to assume that is why i ran alright with out the airbox lid or is that wrong

waterbug89

then move the 175 to the rear correct

8541Hawk

Yes that is why it ran ok on the top end and also why the bottom end was so bad.


Yes that is the correct set up.

waterbug89

i will pick up a jet tommorow and try that thanks

RCVTR

It shouldn't fall on its face with stock jetting and stock exhaust at 5200 ft.

Mine started getting too fat and stumbling at higher (>7000 RPM) at about 7000 ft, with 2Bros cans and 180-185 jets. It wasn't a problem with stock exhaust. Definitely not a problem at 4500 RPM.

Are you sure about the jet sizes? Have they been drilled out, by the PO to try and get it to run without an airbox?

RCVTR

Also...
That sounds like somewhere around the middle of the slide travel (only a guestimate). That would also be somewhere in the middle of the needles.

You mentioned needles with grooves. Where are the clips located on the needles?

waterbug89

it has d&d exhaust and im not sure about the jets i just took the carbs apart to clean them because the bike sat for three years with out being started by previous owner

waterbug89

that i also am not sure of where should i start with the needles

RCVTR

Somebody correct me if I'm wrong, but IIRC, you will probably want to be in the 3rd or 4th groove, with stock mains. 3rd groove with 180-185 mains. That's just a top of my head starting point.

But the reason I came back...

If the PO put a jet kit in, it has a different spring for controlling slide travel. It requires that the slide bodies have a small hole drilled (at least the Dynojet version does). If he put the springs in and did not drill the slides, the thing will probably dumping fuel in the midrange, because the slides would open too early.

Just another possibility.

waterbug89

ok will check it out tomorrow thanks all the info really helps thanks

waterbug89

how do you tell the diff in the jet kits and were is the hole drilled

8541Hawk

That is why I asked what the jetting set up was. If it is not stock (like you said in post #3) then I need to know what you have before I can give any advice.

waterbug89

how do tell what jetting i thought you were talking about jetting size

waterbug89

regardless i will have the carbs apart tomorrow after work and get as much info as i can again thanks for the info

autoteach

recycle the K and N. Sorry, its a worst purchase and should be known to all.

waterbug89

that is what i kind of understand it was on the bike when i got it i think what i gather from this site is that the oem filter is fine right

8541Hawk

Yes the stock filter is the way to go.

Now for the jetting. You will need to remove the needles from the slides (use a diaphragm cover screw and thread it into the needle holder and work it side to side a bit as you pull it out, also be careful as there are washers under the needle and you don't want to lose any)

Then let us know the following:

Do the needles have 5 grooves for a clip (if so what groove-counted from the blunt-is the clip in and how many washers are on each needle) or do they look like a nail with a big head.

How long are the springs for the diaphragms

on the end of the slide that the needle comes out of, how many holes (besides the one the needle goes into) does the slide have

What are the numbers on the main jets and do they have a star by the number

With this info we can get you set up.

8541Hawk

Well mine is on the 2nd grove from the top (blunt end) with one washer on the front and two on the rear but I also have HRC needles and #48 pilots so it might be different with the other kits.

waterbug89

thank you 8541hawk i will have the info tomorrow

8541Hawk

Also one more thing to check while you are in there. On this bike the emulsion tubes are different on each carb. These are the parts that the main jets screw into.

So to make sure someone didn't mix them up (and to make sure they are clean) pull them out and check them.

Here is how they should go:



notice the small holes on the body are in different locations.

RCVTR

I know yours is sorted.

Hopefully this stuff helps people to understand the mysteries of CV carbs.

waterbug89

ok guys picked up a stock filter today what a crock but we will see 56.00 also picked up a 172 main just in case here is the scoop pulled the carbs one washer in front of the clip the needle has 6 grooves the c clip is in number five from the blunt end no washers behind the clip and like i said the jets are as follows 175 up front 178 in the rear and 45 for the slow jet there is a big washer onthe back of part that the needle came out of also all the jets do have stars, what do the stars mean the new 172 has a star in front of it

waterbug89

oh and the spring behind the needle is about 7/16 long also there is to holes on top of the slide and one below so a total of three holes beside the one the needle goes through