Jet needle questions

[craig]

Hi all,

Those of you with better things to do than read my drivel, the key question I'm looking to have answered is this:

What is the Keihn equivelant part number to the stock 1995+ KDX200 (R1174K) needle? Thanks!

On to the drivel.

My '97 220 has been very rich since I bought it. The previous owner had some mods done, and never sorted the jetting out. I'm tired of being the smokey guy and fouling plugs, so it's time to stop being lazy and do something about it.

Background: Dynoport pipe & silencer, porting, bored carb, delta v-force reeds. Fresh complete rebuild - crank, cylinder replate, top end, everything.

Current jetting: 42 pilot, R1173L needle (stock 220) middle clip, 162 main.

Oil is Klotz at 40:1

Symptoms: fouls plugs (seems worse when I'm riding slower stuff), excessive smoke, slightly harder to start when hot (sometimes 2-3 kicks as opposed to 1).

Anti symptoms: Runs great. ;-)

The JustKDX web page suggests using the specs for a modded 200 when dealing with similar mods and a bored carb on a 220. That suggested setting is: 42/45 pilot, R1174K needle (stock 200) middle clip, 152/155 main.

It also suggests that when using Boyessen reeds or a Boyessen RAD valve to lean the pilot/main one setting.

Using the chart on the 'understanding jet needles' page, it appears that the R1173L needle is richer (at least at the taper) than the R1174K.

There is no conversion for the L1 measurement of L, so I have to assume if follows the 'trend' of the included measurements. Doing that suggests that in the L1 area, I'd be slightly leaner with the R1173L needle vs. the R1174K. Of course, I'm not taking the shorter straight section of the R1173L into account, and without an L measurement, I don't have any way to compare that info. This part makes my head hurt.

Considering that I'm running a richer needle, a much bigger main, and delta v-force reeds (which I'll assume have a similar effect to the Boyessen product), it looks like I'm pretty rich. The plumes of smoke behind me tend to back that up.

The porting is a bit of an unknown variable, but I find it unlikely that it requires a main that much richer than the suggested baseline. The main is fairly easy to get in the ballpark by doing a plug chop, so I should be fine in sorting the it out. I'm in the "keep it a bit rich on the main so it doesn't blow up" camp anyway...

The needle is where I'm not sure which direction to head. Is it likely that just moving the clip up (leaner) will get me in the ballpark, or should I just go ahead and get a R1174K (stock 200) needle and start from there.

Just how much richer is a 73 straight section diameter than a 74? I see that a 73 measures 2.735 and a 74 measures 2.745, but I don't have any way of knowing how much fuel that .010 translates to.

Also, in reading the conversion info, it looks to me like the Keihn equivelant to an R1174K is a N427-48BFQ, but I don't see a BFQ in the "applicable needles" chart. Am I doing the conversion wrong, or is it missing? If I'm wrong, what is the Keihn part number for the stock 200 needle?

If you've made it this far, thanks! If you can offer any insight, that'd be great. Either way, next ride I'll be doing some jetting experimenting.

thanks in advance,
Craig

 

[D36-108A]

Stop. Sit down. Take a deep breath. You can't change everything at once. Follow Canadian Dave's carb tuning instructions here.

To answer your key question: I couldn't find an aftermarket equivalent to the R1174K, either and the consensus seems to be it's a special custom Kawasaki needle with no equivalent. But you can get really close to BFQ, like BEP or something.

 

[craig]

Heh, yeah, don't worry, I'm not gonna try and fix it all at once. My thinking/wondering is do I want the R1174K needle to start with, rather than chase my tail using the 'wrong' needle?

Obviously I'll make the changes one at a time, I just think having the other needle may make it an easier process.

thanks,
Craig

 

[23jayhawk]

Some people have gone to a smaller straight section to help with a typical KDX problem, the off-idle lean bog. The needle diameter seems to have the most effect around 1/8 throttle or so. So you may not have a problem with the 73 versus the 74. :cool:

 

[canyncarvr]

For starters, you have the right idea/point of view: 'so it's time to stop being lazy and do something about it.'

That's much better than 'I don't know, don't care and don't want to read anything...what do I use?'

I don't think you'll find much difference from 2.735 from 2.745. In REAL numbers, that's .0005" (or so).

Although your pilot is close, your main is quite a ways off. As far off as it is, it will effect the bottom end circuits of the carb. Set your bike up jet-wise first, then change the needle (imo), otherwise you will HAVE to be changing a number of things at once.....a popular needle choice around 2.695 is going to drown your kdx with a 162. That's given that it's too rich, now. A 162 is perfect on my 200. IN the sand AT sea level with a -30 FmF pipe.

You're right. The porting part is a big ?? Especially if the combustion pressure was increased with head modification.

My .02 cents worth: Start with a new BR8EG plug (fine wire). Set your main up with a WOFT plug chop. That will get you in the ballpark while your pondering needles.

Are you using a DFII or DF? The II has adjustable reed tension that matters a WHOLE lot.

I do agree with jay, a smaller diameter is a good thing. A sharper taper (1.5º or 'C' needle) is a GREAT ride. Kind of hard on your arms, though. A whole lot of 'holding on' going on. Fishhead liked even the 'D' series (DDK/DCK).

Don't forget to pay attention to your AS. 1/8 turn on my bike is a night-and-day difference. Adjust to best throttle response by the seat of your pants.

Have some fun!! I run an 1173N on clip 5 with a 152 main at 3-6000' el. That's specifically set for a particular area/type of riding..and fuel economy.

That same jetset in lower elevations/single track is lousy.

Point is, it depends so much on what you're after!

A smaller main and less diameter on the needle is the right direction, though.

Keep in mind that a smaller diameter needle will start its taper later than a similar L1 needle with a larger diameter. L1 is measured to a diameter of 2.515 (the 'magic number'), NOT to where the taper STARTS! That is (sez me) the single most critical thing to understand when it comes to needles and how they work..the magic number!

Cheers!

 

[craig]

Thanks for the replies. I just read through the RB carb mod thread which has some good info as far as getting me into the jetting mindset.

I'm not sure if I'll have time to ride this weekend, but at the next chance, I'll set the main and see where that gets me. Guess I better order some mains... ;-) I'll leave the needle in place for now, get the main right, and go from there.

I've done a fair amount of jetting in the past, and it's not unfamiliar to me, it's just hard for me to get motivated to spend what little riding time I get tweaking jetting, so I want to have a good idea what my plans/goals are before I start tweaking. After fouling a plug on each of my last two rides, I've found the motivation.

thanks!
Craig

 

[canyncarvr]

A BR8EG will help with the fouling in any case. No excuse for a right-jetted bike.

It may well take some time to get into the right area. Fine tuning will take longer, and isn't really necessary if all you're after is keeping the same plug for a season or two.

You'll get THERE pretty quick.

The AS is still important from a plug foul point of view. My bike can change from a 4-stroking blubbermobile to never miss a beat with 1/2-3/4 turn. That's on a puttin' with the kid on a quad kind of riding day.

Have fun!

 

[craig]

I was running a BR8EG, and it did prolong the fouling, but as you say, a properly jetted bike is the right way.

I'd like to establish a couple of jetting combinations that work for me... say a 'winter' setup and 'summer' setup and maybe variations for altitude (though I rarely ride at any altitude). I'm not one to fine tune jetting with every ride (obviously, considering the jetting I'm riding with now), but there's no good reason for it to be as far off as it is now.

thanks,
Craig

 

[GREENHORNET]

hey craig, Ya might after you have figured out your jetting puzzel want to clean your KIPS Valve and re-pack your silencer. Running the bike real rich for long periods gums up the kips and destroys the packing in thesilencer. You wil get your performance back.