High Altitude Needle Jet Question

[peterryan01]

Hello,

I have been battling with the jetting on my '01 KDX 200, and I am finally just going to ask. I just got finished reading all the stuff about the needle jet on Canadian Dave's page. It gave me a much better understanding of what to do with the needle, but I am still a little confused.

I am currently using a R1175K needle, which is suggested in the KDX manual that came with the bike. It is a step leaner than the stock needle, but otherwise the same shape, etc. Since I mostly ride at 8,000-11,500 feet, I am wondering what else I can do for the needle. How big of changes can be expected from changing clip positions (how much altitude can be changed per needle size)? Does anybody have any info about high altitude needles? Any info you can offer about the needle would be greatly appreciated!

Thanks,

Peter

 

[TVRider]

Peter,

Give us a little more info on your current jetting other than the needle. I just got back from Durango where I rode my 03 200 and was running a 35 pilot, 148 main, CEJ/2 and it ran pretty good at 7500 ft. (which is like crap compared to sea level). I took it all the way to 12,800 ft and it did ok.

Tom

 

[shr]

Tom,

CEJ..., or was that a CEK...?

 

[peterryan01]

TVRider,

I am running a 42 pilot, a 140 main, and a R1175K (middle clip). I hope this helps. I am going to check my float level, also. I think that may be contributing to the constantly rich feeling. I am also planning on dropping the pilot to a 40. My next trip will be at about 8,500 feet for the entire thing, so I don't want to lean it out too much. If you have any suggestions, I would really appreciate it. Thanks a lot for responding! I hope this info helps.

Thanks,

Peter

 

[John Harris]

I have an '01 KDX 200 pretty much stock and just got back from Colorado, where we rode 8,000 to 11,500. Clean air filter, Stock needle (second clip from top) 38 pilot, and 145 main. Ran as well as expected, but still to rich.

 

[Wolf]

Stock is the R1174K, right?

 

[canyncarvr]

Changing altitude and choosing a needle to fit doesn't.......fit, I mean.

The needle will give your bike a 'personality' if you will. It will have a lot to do with the power band that the bike 'hits' at and how hard that hit is. It determines the rate at which the fixed jet delivers fuel.

But you don't generally change the needle to 'match' an elevation change. You accomplish that by changing the pilot and main jets.

So, if you have a needle that suits you, and you take a vacation to the rockies, leave the needle alone, change the pilot and main.

That's why you see jet correction values (as on CDave's site) for elevation changes, but not needle correction values.

Not that it matters a whole lot...but for some sort of reference, my last ride to around 6500' (and about 80º) I ran 38/148 in my 200.

How did you come up with a 140 main for your 200? That sounds pretty skinny already....even for 8500'

 

[TVRider]

shr,

I swapped the cek for a cej I had just for grins.

Peter, listen to CC and do a WOT plug chop to check your main. With that skinny a main, I wouldn't run it too long for fear of seizure! I don't have any words of wisdom other than keep reading and asking questions.

Tom

 

[G. Gearloose]

An 1175 has only a leaner straight section, not everywhere. So using an 1175 in the middle clip is much like using an 1173 or 2 in the middle clip, once your off the straight section; 1/4 throttle and up.

Most everyone finds this too rich on the flatlands, you must be blubbering heavily mid throttle at altitude on the middle clip.

Go ahead and drop the needle;

Don't drop to a a 40 pilot yet, the pilot can't compensate for the rich needle setting you have; they will be working against one another.

And I concur, recheck your main. You did modify the airbox, right?

 

[G. Gearloose]

Originally posted by peterryan01
I am also planning on dropping the pilot to a 40. My next trip will be at about 8,500 feet for the entire thing, so I don't want to lean it out too much.

Does this mean you're going down in elevation for this ride?

 

[canyncarvr]

FTR, running an 1175 and 1173 thru JD's spreadsheet shows them to be the same just above 3/16s throttle.

You cannot go (just/only/merely) 'one step leaner' with a needle. You can go leaner on the diameter, you can go leaner on the clip, you can go leaner on the slope, but to say 'one step leaner' is leaving out some critical information. Each of those changes has effect in different throttle positions.

The point is to reiterate what Gearloose said. Changing the straight diameter is going to effect things like plug loading on long downhills and transition 'hit' when you pull the needle off the straight. It will not have much at all to do with meeting high altitude requirements.

Recheck your main for sure. I'd advise not checking it with a WOT run that's longer than 10 seconds for sure, cuz it sounds too lean to me!

 

[peterryan01]

Hi,

Well, I'm a little confused. Since I ride over 8,000 feet pretty much everytime I ride, I am getting a pretty good feel for how the jetting is working. However, everybody seems to say that I'm too 'lean' (as in too much air). This causes me a little concern. With a 42 pilot, 140 main, and a 1175 needle (middle clip), my bike absolutely screams at 5,200 feet (mild signs of lean show). When I take this jetting up to 9,000-10,000 feet, the bike doesn't want to go. It likes to stall and bog (an obviously rich bog) in the low end. Throttle response is terrible up high, but is excellent down at 5,000 feet. I just took out the 42 pilot, and put in a 40. Hopefully this works okay. I will let everyone know. My plugs are coming out great (maybe a little rich) - tan, with a touch of oil. I am going to try the 'lean' setting and see how it goes up high. I am trying to study up on C.Dave's needle info, but it is a lot to take in.

Also, what do you guys think of 'side-gapping' spark plugs?

Thanks,

Peter

 

[canyncarvr]

If you haven't (and I see no indication from you that you have) checked your carb's main jet with a WOT plug chop, you don't have anywhere to start from.

Your last post indicates you didn't read the posts preceeding.

Again...chances are a 140 is too lean. I dunno for sure. Check it.

Your comment on 'tan' color I'm afraid indicates you aren't familiar with plug reading for air/fuel mixture.

Read this for some most excellent input on the matter.

'Tan' or any other color of insulator tip doesn't apply to air/fuel mixture.

You have some checking/reading/testing/tuning to do, methinks. ;)

 

[peterryan01]

Well, I went for a ride this weekend, and it appears that my bike is a bit too lean. I finally got 'lean bog'. I think the pilot circuit is right with a 40. I'm pretty sure I am going to be running a 142 main for the high rides (8,500-11,500 feet), and it sounds like I am going to need to drop the stock needle back in. Does this sound right? After my trip, it was discovered that for an FMF Gnarly pipe, a 'step leaner needle needs to be installed' (this is from the FMF instructions). I am assuming a 'step leaner needle' means '1173' instead of '1174'??? I am currently running a 1175, so I think I'll put the 1174 back in. Does anybody know if the Kawasaki needles (1172, 1173, 1174, 1175, etc) are proportionately leaner, as opposed to just adjusting needle length via clip adjustment??? So, back to the 1174 it is. Hopefully this cures the problem. Otherwise, thanks for all the suggestions. I am going to try to get the performance more dialed in via jetting, and hopefully get some good plug readings out of it. I'm just going to go up to 8,500 feet and have a nice little jetting session, and hopefully get the jetting to where it needs to be.

 

[JasonWho]

---

 

[peterryan01]

I made a boo-boo. I meant to say that the FMF instructions say to put in the "next richer needle", not the "next leaner needle". I am going to put in the stock needle (1174) to richen the jetting from the 1175 I have in now. I apologize for the confusion.

Thanks,

Peter

 

[canyncarvr]

I'll bite...one more time.

re: I am assuming a 'step leaner needle' means '1173' instead of '1174'???

This reference has been made a couple of times....and answered. Your assumption is incorrect. Substitute 'richer' for 'leaner'...and it's still incorrect because you have to say richer/leaner where in the throttle range.

Probably the least difference overall you can make to the carb with a needle change is a change to the straight diameter. It effects the smallest part of the throttle opening range. That could be subjectively argued if you're working with an off idle response or plug load-up problem. In that case, it would be a 'big part' of things to you.

As jw indicated, if you are looking for a 'step' in one direction or the other with the needle, clip position and taper are more of an overall 'step' than diameter.

You have to know what throttle position you want to effect before you can make a reasoned decision on what to change.

And you have to set the main before you mess with anything else.

Riders on this forum are glad to help and answer questions. When more questions are asked with insufficient regard to answers already given you'll likely find the resource dries up after awhile.

Have fun with your 'jetting session'. A properly jetted bike is much more fun than a sputtering, spooging goober bike! ;)

 

[peterryan01]

Okay.... I'm still lost. Are you saying that the R1172K, R1173K, R1174K, etc, only changes ONE variable about the mixture? Aren't the needles Kawasaki recommends proportionately leaner or richer (ie 1172 richens the entire range while 1176 leans the entire range)??? After reading the tutorial about needles that was presented on this forum, I am still confused as to what needle dynamic changes what jetting variable. There are a bunch of charts with needle numbers and letters, but none of the info seems to say what/how each number or letter changes what jetting variable. If I were to select a needle that richens the low end, richens the mid-range, and righens- the top end, how can I tell what slope, clip, and diameter selection I need to make? Is there some sort of equation for this? If so, how do I find it? I've been messing around with jetting for nearly two seasons now, and I really just need to get it right. I've had it close to right a few times, and loved it, but it seems like an uphill battle. I really appreciate the help, though! The tips are priceless! Are there any articles online that speak more about the dynamics of needles that you guys have found useful? Any links like that would be excellent! Otherwise, I am going to keep studying the forum and hoping to find what I need.

Thanks again,

Peter

 

[canyncarvr]

re: '.. but none of the info seems to say what/how each number or letter changes what jetting variable.'

The cynical voice in my head says, 'Yes it does...if you read it.'

The kinder, gentler voice says...(take a deep breath........)

CDave's site has info on carb tuning and needle decoding that tells you most of what you need to know. I made reference to it from the git-go..but maybe you don't know where it is?

Click HERE to get to his site. Read the carb tuning and needle decoder sections under <tech tips>. One of the graphs you find there is:

 

[canyncarvr]

You can see from the attached chart that there are different throttle positions that are effected by: Air screw, throttle cutaway, straight diameter, clip position needle taper and main jet.

So, when you say, 'Are you saying that the R1172K, R1173K, R1174K, etc, only changes ONE variable about the mixture?' the answer is YES!

What changes in the above needles is the straight diameter, namely:

• '72' = N = 2.725mm
• '73' = ?? = ??
• '74' = ?? = ??

You can tell from the chart above that needle diameter effects mostly the lower 1/4 opening of the throttle. Other similar charts show a bit different gradient, but you get the idea.

Rather than list a whole bunch of stuff that gets glossed over, you tell me what the correct values are for the ?? above. I've supplied the sources to get the answer. Your answer will let me know you looked 'em up.

Then we'll go over some links with great information on needles, some programs that will allow you to graph the effects of needles, temperature, throttle valve cutaway, elevation......all sorts of stuff.

BTW...re: 'After reading the tutorial about needles that was presented on this forum..' What does that mean? What 'tutorial' are you referring to and where on 'this forum' is it?

 

[peterryan01]

Okay, this is all coming together now. Thanks for reminding me that the 'tutorial' is on Canadian Dave's page. I simply forgot where it was. I have two print outs now - and they are beginning to make sense. Now I can complete your chart:

'72'=N=2.725mm
'73'=P=2.735mm
'74'=Q=2.745mm

That makes sense now. THANKS!

If you have websites, or spreadsheets that can help, I would REALLY, REALLY appreciate it! Any additional help would be awesome! I'm getting close to understanding this, so it would be nice to have some references to cross-check my ideas with.

Thanks again for the help! I'm sure it is a pain, but it is highly appreciated.

If you would rather email the links for the sites, my public address is 'CU_KDX_Dirtrider@hotmail.com'.

Thanks,

Peter

 

[canyncarvr]

Thanks for the answers. Now I know there is electricity happening in the synapses! ;)

CDave's site is commonly confused with this forum. While the two are hosted by the same outfit, and obviously related in subject matter, they are not the same thing. That's largely why the 'Every kdx rider should read...' is stuck to the top of this forum...to help people get from one to the other (it's easy to get from CDave's to here..but not quite as simple the other way 'round).

A couple of things:

1. Try some searches with different words (needle and/or carburetor may be a couple) and see what you come up with.

2. If you haven't read thru THIS THREAD , then give it a go. It's long, and not all related to what you're after, but it's got some critical carb-tuning info in it.

3. In the above thread you'll see posts from JD. While he can't tout his own stuff, I can! ;) He has a spreadsheet available (yes he charges for it) that will allow you to do what I mentioned earlier. You can enter jetting (pilot, main, needle, clip and TV cutaway) and ambient info (temp, elevation and such) for five different setups. You get graphical representation of the needle slopes and % change.

Besides that, you get some info on suggested needles for different carbs.

I use it. It's a great tool. You can check it out HERE!

4. Look around the web for related info. Try google searches (google.com) for some carb outfits (sudco, carbparts and mxsouth are a few). You'll find some more charts, graphs and info. Mxsouth has a chart (well they used to, anyway) that shows different needles in a richer<-->leaner grid that may be of use to you.

BTW...some of the proprietary kawi needles (of the Rxxxx-x type) do not cross directly to a keihin needle. In that case you can interpolate between known numbers to get a 1/2 way decent guess as to what the keihin # is.

JD's spreadsheet does take input like R1173L and graphs it along with keihin #'s like CEL, DDK and the like.

Have fun!

An item of considerable importance that may not be crystal clear in your reading (it should be if you read it well)....consider that the L1 value in needle geometry is a length to where the needle is 2.515mm in diameter. It is not a length to where the taper starts on the needle.

This becomes very important when you realize that an 'A' taper needle (1º taper) compared to a 'C' taper needle (1.5º slope) of the same L1 will start its taper earlier because the slope is slower, so it takes more length (farther) to 'get there' (there being 2.515mm).

In real life, you'll find then (in a particular given situation) an 'A' needle much richer on the bottom (lower throttle position) than the 'C' of the same L1.

JD's sheet will show you that, too.

Interesting how it all works, 'eh?

Have fun!! Oh......I said that already........

Cheers, then!! ;)