just short of perfection

[est142]

OK...I should just be happy with how it is now...but perfect is always better. Need jetting tips for a 97 220 with just a little bit of stumbling from idle to 1/8 throttle. 145/42 jets ,stock needle at 2nd from top clip groove, air screw 2 turns out. It does at little "bup bup bup" before it smooths out and rolls on great above 1/8 throttle.seems a tad rich,but should'nt I be able to clean up this little problem without jet swaps? sea level rider. runs mint everywhere else in the throttle range and will pull the front tire up without any clutch work or body movement.

ok experts...any thoughts??

 

[John Harris]

Every bike is different, and the proper jetting procedures are detailed on this site. I believe your will be close to perfect if you run in the next to the top clip position on the needle. I was not sure if you were in this position or the one below it. The other thing it sounds like is that you might want to try a one size leaner in the pilot jet (40). Takes me more than a minute or two to change the pilot jet, but has always been worth it.

 

[est142]

Thanks jh.

I was in the middle clip groove to start with. I was thinking about doing what you mentioned, just like to here that someone else would make the same call. I am already 2 turns out on the as so that's about it for the 42 pilot...plus its about 50 deg here so things will only get worse as spring begins. When a bike runs so good, it is just annoying to have to here three or four bups before things get rolling.

 

[bleedngreen]

bup bup bup

What's up, est...
I had a similar situation with my '99 220; before I sent my carb to Ron at RB Designs...

I worked with my jetting for weeks and my bike ran really nicely--except for that little bup bup bup at very small throttle openings. My reworked carb is SMOOOTH from bottom to top with more usable power everywhere!!

If you want to stick with the stock 33mm carb bore though and you're confident that your jetting is as close as it's gonna get, I'd bet that a leaner slide would clean up the bup down low.

Dave

 

[canyncarvr]

You're kind of beating a pretty close to dead horse changing the clip on the R117xx needle (imo).

Chances of ron putting the stock needle back in after he's done with it are about zip-point. Better chance you have a 'C' or even a 'D' angled needle in the RB carb now.

Lengthen the straight section of the needle. You can make the straight section come on later by lowering the needle, but you haven't changed the relationship of the straight section to where the taper starts (given the same L1). THAT happens only when you change the slope (the oem 'R' needle is a 1º 15" slope, a 'C' is 1º 34", a 'D' is 1º 45", OR 1.25º, 1.50º and 1.75º respectively) of the needle.

A CEL with the stock slide (5mm cutaway) is probably a good starting point. A 6/7mm cut slide would help.

I never did get the low end burble out of my kdx until the slide/needle combo was changed.

 

[skipro3]

Not sure what part of the country you are from est142, but if you get a chance to ride at elevation, and the performance improves, then I would think the pilot / airscrew could do with some fine tuning. I'm running a 143 main and 35 (I think, might be 38) pilot.
I don't think the needle would have too much affect with 1/8 or less throttle opening but hey, I've been known to be wrong. (and justifiably had it pointed out in spades)
You might also adjust your float level. A lower float in the bowl will lean out the mix.

 

[est142]

I like all the input. RB carb bore would be great...but if I spend anymore big $ on the bike this month...she will cut them off and fry them up for supper.
CC- My jetting basics are solid, but I have not yet studied the function and characterisitics of needles. I have the stock R1173L 2AFLP in it now. the bumps when slowly rolling the throttle up, are just barely above idle speed, when running in first or second gear. I thought I was underneath the point where the needle shape could cure anything. what needle would you use?? all sea level riding. your needle tech post above, blew right over my head at lightspeed.
I am using a ngkbr7es. could I pull a rabbit out of the hat by using a different plug??

I know someone must have fixed this problem on a kdx 220 by now!! thanks in advance

 

[est142]

oh yah, forgot to mention. when I try to richen up slightly by turning in the AS, I end up with more bup x 5 instead of bup x 3. Am I right calling that bump, too rich...just over idle?

 

[wibby]

Ê
RB carb bore would be great...but if I spend anymore big $ on the bike this month...she will cut them off and fry them up for supper.

But the month just started! :clue:

 

[cicone]

But the month just started! :clue:

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ I try to avoid mountain oysters---especially if their mine! :eek: