24mm sunworld jetting

[neveready]

We are having trouble getting our carb setup on our new 90. It idles fine and takes off like a rocket in you pin the throttle. The problem is if you let off any or take off without going wide open it stutters and falls on its face. It has the spacer plate top end with pretty agressive porting. I know it should have smooth response through the whole throttle range. The only way I can get it to imporve any is I am now running the clip all the way at the top. Which tells me it is too rich in the mid section. My engine builder says not to rejet because then it will be too lean wide open?? What are my options?? Current jetting is 135main 45pilot. I would think I need a smaller main to get the clip back up and make smooth power, but jetting is not my specialty. Thanks

[bulldogfallon]

Your engine builder should know their engine?

Who did the work?

[Reimer Racing]

On zacks 90 I use a Keihin 24mm with the jetting at 150 main 48/50 pilot and the clip in the middle. We tried using the OKOs and never could get them to run right. I would toss the carb and get a keihin. Just my 2 cents

[neveready]

Our engine builder knows these engines very well. I truely have no complaints about him. (yet) But i like to get other opinions as well. It just seems to be this carb that is giving us problems. uh,I think? If you run it pretty well wide open for a good period it gives a good plug reading. It will idle all day, and will throttle up from idle with no hesitation. Like I said before it just is in the middle like if you are coming out of a curve where you never really idled all the way down and are not back at full throttle yet it just stutters really bad. Or if you just try riding at a constant 1/2 throttle. Before I lowered the needle all the way I could hold the bike still at 1/2 to 3/4 throttle with hanging on to the grab bar. When I lowered it all the way it is a lot better but now I have no more adjustment. Our guy says we need a needle with a different taper, but not to rejet??? it seems to me a smaller main would help, am I wrong? or is this a pilot issue? I have a few carb options to choose. I have a PE24, a OKO28, and a 28 Mikuni flat slide. What do you all think? :confused:

[dericsdad]

So try a 42 pilot, clip in the middle, and see what it does. be sure to adjust you air screw properly after changing the pilot also.
Try this wb site to better understand how to jet your carb: http://www.keihin-us.com/am/

Dan

[forgiven]

Depending on how radical your engine is, a 28 might be worth a look but I have a hard time believing that you are so grossly under carburated or at all that it would cause an issue like that.

This may sound dumb since it is a new carb etc. but did you take it apart and clean the bowl and floats real good with cleaner, and check the motion of your floats?

I had an issue similar to that with my Predator 500. I changed up my intake quite a bit and I needed to move to a richer needle. It was quite a pain in the arse and quite honestly I got it real close but it was never right. A lot of time was spent on it and I ended up waiving the white flag and sending it off to be modded and it was turnkey when it came back.

When you start changing a bunch of stuff it is difficult to say exactly how things are going to react unless you have a lot of experience with that style of motor. Keep us informed of your progress and if you could let us know what has been done to the motor/intake so far that would be great.

[mxdad423]

neveready, check your messages........

www.bakmotorsports.net

[quad1rider]

I am not one to give advise on this issue right, kevin ? but it seems to be a problem i had as well and it was fixed by changing the pilot jet i would not use anything from now on but keihn so i would say use the pe24

[saintmick]

I have come across this problem a couple of times the first time it was the carb no matter what you did to the set up it would do this the rollers alter the fueling also to (heavy)

on my sons quad we run 148 main 42 idle but we drill another hole in the carb by the fuel inlet to let the bowl fill quicker this can elimanate a similar problem to what you are having

probarbly end up being the carb i'd change to the 28mm oko good carb for the money

[bulldogfallon]

Originally posted by saintmick
I have come across this problem a couple of times the first time it was the carb no matter what you did to the set up it would do this the rollers alter the fueling also to (heavy)

on my sons quad we run 148 main 42 idle but we drill another hole in the carb by the fuel inlet to let the bowl fill quicker this can elimanate a similar problem to what you are having

probarbly end up being the carb i'd change to the 28mm oko good carb for the money

I was thinking rollers too, but it is hard to say without hearing the engine run

Tooheavy of rollers can make it lazy, but I am not sure that is what you are describing to us..

Could be a combination of both? Roller weight and jetting?

[saintmick]

it will be one of the above
when you say spacer plate at the top end are you running a bigger crank we spacer the cylinder from the bottom of the cylinder works better for us:confused:

[neveready]

Our spacer is at the bottom, I have 4.2g rollers and a molassi red comp spring. 1500rpmshoe springs, it is not lazy at all,it is a rocket at w.o.t. just chokes out and sputters at any less (rich,slobbering rich). I am going to try a few different needle tapers and then if no luck go to my 28mm oko. It runs really well on our 109cc outlaw motor now.

Thanks to all of you. I'll keep you posted.

[neveready]

Ok I used the needle from our 28mm OKO in the 24. It is the same length just a faster and fatter taper. I still have the 134 main and a 42 pilot, running that needle on the 2nd clip down from the top. So if anyone is using this mirror polished 24mm sunworld carb I would reccommend this needle to save some headaches later. Thanks again for all the help.