idle to 1/4 throttle 4 stroking !

[rogergendron1]

ok the bike idles perfect and from 1/4 to wot the bike takes off like a bat out of **** and is perfectly tunned !

but if i try to drive real slow 1/4 throttle or below it four strokes ! i know its not the needle, or the main jet and i do not think its the idle jet because it idles perfectly and my iar fuel mix screw is turnned out 2.5 turns so its got pleny of air the air filter is clean and it still does this with the air filter off soo

i am thinking the float bowl is set to high ? could too high of a float make from idle to 1/4 throttle 4 stroke ?

ohh this is a cns carb and acsept for idle to 1/4 the bike is running awsome and well tunned plenty of power and great plug color lol so i just skip right past 1/4 and go lol i dont want to do this any more as i need to be able to ride slow and do it smoothly

any help would be great..

 

[GearNut]

The idle mix screw controls exactly that, idle mixture. It also has a slight effect at just off idle.
After that the low speed (sometimes called "idle jet") jet controls the mix from just off idle to 1/4 throttle.
After that the slide needle controls the mix 1/4 throttle to 3/4 throttle.
After that the main fuel jet controls the mix 3/4 throttle to full throttle.

Note that all the fuel circuits do have an effect on the next circuit to come in control.
Sort of an overlap when one fuel circuit has done it's job and the next one is starting to work, depending on the throttle position and engine load.

Just by reading your symptoms, it sounds like you need to reduce the size of the low speed jet. Start off by reducing it by one size and test it. If you are not happy with the results, reduce it again and test it again. It is better to sneak up to a good tune with many changes and tests rather than make big jumps in jet size, ect. and get radical changes from test to test.
There are many threads on the CNS carbs.
Here are a few to get you started:
http://motorbicycling.com/showthread.php?t=30169
http://motorbicycling.com/showthread.php?t=25062
http://motorbicycling.com/showthread.php?t=30179
http://motorbicycling.com/showthread.php?t=49419
Look around on this site for many, many more.

 

[rogergendron1]

i adjusted the float VERRY GENTLY down and it helped a verry litttle.... so i am going to change the pilot jet out to a smaller one .

question ? where do i buy the pilot jet lol i can only find main jets ! this is a mickuni clone right so should the mickuni pilot jet fit the cns ?

i know a good bit about carbs, and how to tune them, i am verry fimiliar with this type of carb as i have about 3 of them on my 3 honda trikes albeit they are bigger 21 - 27mm !!! i just thought that the idle jet / pilot jet was already pretty small lol it must be to big though cause the float adjustment didnt change mutch i still have that idle to 1/4 4 stroke lol i was reay hoping the float was the issue so i wouldnt have to go buy a idle jet for a clonee carb that may not exist !

by the way this is the type of carbs i am used to kien carbs with fuel acselerator pumps ... so most of my four stroke have a dual throttle cable twist throttle one for the acsel pump !!!!

 

[rogergendron1]

well if the float was not the issue and my idle air screw is out 3 turns and i still have 4 stroking of idle to 1/4 throttle ... the idle jet must be to big ...

correct ?


what is the stock size of the cns v3 idle jet ? i am going to solder it shut and redrill it but i need to know the stock size for a referance point



too bad .... cause EVERYTHING esle about this carb is tunned perfect !!!!!! lol and i do know by the way that four stroking of and on a little wile riding a flat with no load means its tunned right ! well for a piston port 2 banger any way . this has a real four stroke problem at idle to 1/4 then it snaps right out to a clean 2 stroke and rips off like heck ! it will break in and out of 4 stroking verry slightly on a flat with no load wile cruising witch to me means its tunned right everywhere else !

 

[dodge dude94]

FWIW, mine 4 strokes at 1/4 throttle, but I just deal with it because it goes like a banshee once I open it up. lol I'll take it being too fat on the bottom end to it being too lean on the top end.

 

[rogergendron1]

FWIW, mine 4 strokes at 1/4 throttle, but I just deal with it because it goes like a banshee once I open it up. lol I'll take it being too fat on the bottom end to it being too lean on the top end.

thats how mine is !!!

the instance i twist past 1/4 it takes off ripping away with pleanty of torque and powwer !!! plug even looks perfect !!!

it just agrivates the h3ll out of me that i cant cruise real slow when i want ... its ether stop or go fast, there is no slow and if i try to ride at a slow cruise just off idle and put around it 4 strokes and has no power... twisst the throttle to get past the little bit of 4 stroking and rrrriiiinnnnnng ding dinng rinng ding !!!!!!!!!!!! it takes right off speeding !

i can not find an idle jet any where for this cns v3 carb !
i may deal with it for 2 more weeks and buy a walbro carb and adapter plate from jnm motors and just do away with the standard stlye carb altogether, it would be great to have a carb that will run in any position and not ever need a float adjustment and never have to change a jet ! and to change jetting all i would need to do is twist a screw ! i imagine the throttle responce would be better with the walbro butterfly style carb than the round or flat slide carbs would any way. ( more open space for flow and less turbulance around the butterfly than trying to squeze under a slide)

 

[rogergendron1]

ok never mind i fixed it...

all i did was open up the stinger pipe on my exhaust from a 1/2in to 3/4in and the 4 stroking went right away .. i guess it just needed a more free flowing exhaust as 1/2in was choking it a little.

 

[dodge dude94]

Cool beans. I know mine always ran better when I just flat out took the cap off. I did some major massaging to it and it works better with a nice sound increase.

 

[Wickedest1]

@rog...open ur exhaust baffle cap...check fer baffles...clean exhaust chamber...then add holes in each baffle, offset from previous...plug chop...rejet if necessary...