Jetting 36mm carb EXC200? JD jet kit

[camchain]

I'm pretty green Re jetting, so I've had a big trawl through jetting threads. Made a few notes, but at this point I'd be real interested to know what setup others are using in their 200s. Plus to what extent richer changes usual for winter? Note this particular one is '07 36mm carb, earlier models had larger carb. I think they switched for more velocity = smoother lower end (?).

Bought a JD jet kit on shop suggestion, so owner's handbook jetting chart not totally applicable now.

In the JD kit:

Mains are 160,165,170,175
Seems a fair bit towards richer end of spectrum compared to stock chart, but sounds like a good idea to me especially with 14/48 low-geared 200 on faster gravel type sections. I tend to lag behind pace here for fear of a you-know-what)

Pilot is 38 - instructions suggest using this if running spark arrestor (hell - that still seems very lean).

Blue needle and Red needle. Haven't a clue how these relate to stock NOZ type needles. Have the feeling the two kit needles are maybe same size/taper but swapping between them offers 1/2 clip equivalent steps? Anyone know?

I'm keeping notes on changes and even taking thermometer along.

Brew is 45:1 Motul 800 - Currently on 42 pilot, 170 main, Blue needle 3rd clip. Air 1 1/2.

Float seemed a little high so dropped it a touch. Found KTM handbook float height instruction a bit vague. Anyone have a better way?

Hope I'm in the jetting ball park, maybe drop back to 45 pilot and some needle fiddling? Was pretty smokey first hour of running in new top end, cleaned up a lot now, but still some annoying black spooge at muffler (has had fresh repack). Intend to do a plug chop or two and quite keen to try some of this wet-line jetting at some point - when I can find a good place to do this stuff! How does where I'm at compare to others settings? How good are the owner's handbook jetting charts? Cheers.

[Reckless]

Well my 2c is jetting is done for the rider not by the book!

Mine for instance is not jetted perfectly but it goes as well as I can handle as a rider. If you take the plug out after you chop it off during a hot run its a bit wet around the outer with a copper colour inner. Which (to me) means it could be a bit leaner in both areas especially the low end. And it does produce a very small trail of stouge that doesn't quite run down or drip off the outside underneath of the muffler after a few hours riding.
But its how I like it, delivering smooth, fat power, at a much faster rate then I can handle, right through till it over revs! It still pulls ok off pipe as well! I believe the slight richness fattens the power and at my level helps my riding and keeps my reconditions wider apart! If I can ever out ride it or as I get better I'll have a play then

There are correct methods for getting it perfect Danger discribed them in another thread, you need a few brand new plugs and a good stretch of track. Do a search if you can find it, its very good, had pics and everything.

But a perfectly tuned bike may not actually be how you might prefer it??

[humai]

Your JD kit should have instructions and guidelines that will allow you to start in more or less the ballpark place, jetting wise.

My 03 200 has the 38mm PWK carb so my settings may not necessarily apply to your situation.

That range of mains you have looks about right. I run between 175 and 178 depending on where I am riding.

The standard setup for a KTM two-stroke with a Keihin PWK carb usually involves use of a "N0Z x" series of needle (Mine was N0ZG stock). These triple taper needles are notoriously rich and blubbery just off idle up to around 1/8th to a 1/4 throttle (depending on clip position), contributing to the typical spoogy KTM exhaust condition. This is especially evident when running the #6 cutaway slide that the KTM two strokes ran in 2000 - 2002 or so. Mine is a #6.5 slide, which is slightly leaner just off idle than the #6.


The needles supplied in your kit should greatly improve this situation.

FWIW, I am now running an N3CH needle (OEM Yamaha YZ250 needle), which has cleaned up the low throttle behaviour dramatically.

I don't know what instructions normally come with a JD kit but, judging by the www.jdjetting.com site, James Dean is a good engineer with meticulous attention to detail on this subject. If the supplied instructions don't cover off what you want to know, drop him a line. I'd say the needles and jet range supplied in the kit should be pretty close to the mark.

BTW, with float level setting, there is, somewhere in existence, a precise, exact float level but as a general rule of thumb, the needle valve should shut off when the moulding seams on the plastic float itself are roughly level - that is, roughly parallel with the face on the carb body that the floatbowl mates up against.

Edited to correct factual data

[Danger]

Interesting subject, I've used JD needles in the RM250 but not in the KTM200 and like humai my 200 has a different carb so my settings would not apply. I'm surprised at the leanness of the mains humai is running and the N3CH needle must be an interesting profile.

When you change the profile of the needle the main required also changes because you don't want either the main or the needle to restrict the engine from getting enough fuel. This is a common mistake and a lean main can make the rich needle position feel correct and its why I tune the needle without running a main. Then tune the main to supply the correct fuel for full throttle operation.
I run a CEK straight taper needle in my 02 200, 6.5 slide and a 185 main in summer and a 188 main in winter. Big difference huh? If I ran a 165 I would quickly starve the engine of fuel resulting in a burnt piston. The CEK straight taper needle provides a smooth electric type power band with no jetting related hit. It is a fat needle in profile in comparison to the NOZ series needles. There are other straight taper that will provide more hit but if I want more power I just open the throttle more, this way I control the bike rather than the power controlling me.
Because the CEK is in my bike I can't mic it up but I have the JD needles here in front of me and a CEJ. I cannot confirm but have heard that the JD needles are the same for all applications. If that is correct I can't see how they can possibly be optimal for all applications. I know I could never get them to work well in my RM250, it was always lean somewhere in the range. The '05 RM250 changed to a 7.0 slide, the instructions included applied to the earlier 6.5 slide, when I brought this up with JD he conceded that the earlier settings would not necessarily work.
So persevering with the JD needles through out a summer and a winter and continually making changes I ended up going back to either the stock NECH or the NEDH needles depending on season. Things are dialed in now and the power is much stronger than with the too lean JD needles.
But they may be good for your bike and an improvement over the NOZ series triple taper needles.
If I mic up the JD needles the blue needle is richer than the red needle from the get go, but then the tapers are the same. So only the bottom end is richer using the blue needle instead of the red. Being summer you might want to run the red needle, clip position to be determined, start in the middle would be my suggestion and tune from there.
It appears from the profile of the needles I have that the JD needles should be leaner of the bottom, leaner through the middle of the taper and leaner at the end of the taper than the NOZ needles. This would indicate that you will need to go richer on the main in comparison to the NOZ series needles and as with my straight taper needles that I use.
Now your JD needles might be different to the JD needles I have, but if they are the same as I have heard (and it might be the grind through the middle of the taper that differs) then hopefully what I have added gives you food for thought.

[humai]

I run a CEK straight taper needle in my 02 200, 6.5 slide and a 185 main in summer and a 188 main in winter. Big difference huh?

Being a straight taper, your CEK is probably considerably "fatter" and consquently leaner at full throttle than a triple taper like the NOZ, hence the need for a larger main. I found when using the "C series" brass Sudco needles over the NOZ needles that I had to increase the main 2-3 sizes.

A 188 does seem extraordinarily rich though. My 200 came with a 180 stock. What air filter / air filter treatment do you use?

Edited to correct factual data

[Danger]

Exactly, I think I said that.
I use Motorex filter oil and a filter skin. It wasn't until I used a 190 main that things got to rich.
Funny thing is I run a leaner pilot than most.

[humai]

Whoa!! - I screwed up - I just went up to the shed to double check my settings and bugger me, I'd got it mixed up with another bike I do jetting on. That'll teach me to rely on memory. I've gone back in the thread and corrected the erroneous numbers.

I'm using a 178 main and go down to a 175 when the altitude is about 2000 feet - the bike came with a 180 stock. With a straight taper, this should be in the 180s somewhere. My apologies to all for the conflicting info.

Your JD mains supplied in the kit seem lean compared to the above but the smaller carb diameter and consequent higher airspeed may explain some of the difference.

[Danger]

That makes more sense.
My understanding is that the new smaller carb does run leaner mains but I have no practical experience jetting one. I know the power seems softer than the earlier models like my bike. Sheesh next thing they'll be putting the mangina starts on the things! :laugh:

[dammad1]

That makes more sense.
My understanding is that the new smaller carb does run leaner mains but I have no practical experience jetting one. I know the power seems softer than the earlier models like my bike. Sheesh next thing they'll be putting the mangina starts on the things! :laugh:

Lets hope so:woohoo:

[camchain]

Re muffler drool. Cheers Reckless. Exactly the type of extra comparison info I was after. Mine left a short trickle out of muffler yesterday so guess I have some safe room to move. I'm with you on staying on the rich side for safety and good fattish power delivery. Can't see much gain in jetting super crispy and risking super crispy engine. But not keen on gooey muffler packing or carboned up engine either. Want to try some leaner settings - just extremely wary about going too far and screwing up. How far can you go safely? Not intending to do this but for instance, could summer jetting cause a seize in winter?

With plugs being $30 a pop, I want to get to a good setup quickly, so only intend to use chop & wet line to confirm and maybe do some tweaking either way.
Have plucked & saved plenty of general jetting info from other threads but just seems like I could spend a lot of time trying different combinations. Especially if lacking solid experience/knowledge to feel the differences. Hence figuring I could do with some more model-specific ideas/info.

When doing a plug chop or wet-line test, my impression is that it could be useful to try and find a steep hill to get some load on the engine. Wouldn't having the thing revving it's guts out with no load give you a bit of a false read - not to mention seems like being bloody hard on the engine? What about dragging the brakes, would that be of any use?

:::::::::::::

Thanks for that humai, especially the needle info. Might also help explain the seemingly very lean #38 pilot in the kit. May give the 38 a quick try just for comparison (after I sort my floppy power valve issue out). On KTMtalk it seems others are using a variety of non-standard needles, and needles seem to offer more in the way of subtlety with finer tuning than jets do? Was told the JD needles were multi-taper but they look straight to me.

This is my second JD kit, I put a one in the KLX300 and it really helped to wake the thing up on the bottom end. The instructions were a bit vague in both kits but this one basically said start at max richest and work from there.

My carb has a #7 slide. Might just be in balance being smaller carb, or maybe to lean the bottom end a bit more than previous models? Interesting that the owner's handbook says replace slide at 100hrs. At $400+ - not bloody likely. Can't see how a little bit of slide wear could have much affect anyway?

I think I should take another look at that float level. No 60 deg protractor so just propped up handbook and tipped carb to line up with angle in photo! Kind of hard to pick the exact point when float valve is seating. Had it apart and valve/seat look good though.

-----Uh Oh. While pondering Reckless and Humai posts, then having a bit of a type, more knowledge since has been dispensed.------

[noobi]

Plugs for $30?
that cant be right, are you buying the EIX iridium racing plugs or something?
When you do the jetting off the plug reading use the $6 dollar ones instead, I didn't notice much difference between the two plug types

[Reckless]

Re muffler drool. Cheers Reckless. Exactly the type of extra comparison info I was after. Mine left a short trickle out of muffler yesterday so guess I have some safe room to move. I'm with you on staying on the rich side for safety and good fattish power delivery. Can't see much gain in jetting super crispy and risking super crispy engine. But not keen on gooey muffler packing or carboned up engine either. Want to try some leaner settings - just extremely wary about going too far and screwing up. How far can you go safely? Not intending to do this but for instance, could summer jetting cause a seize in winter?

I'd better qualify my comments a bit I tend to tune on the rich side because pretty much, I can't ride the thing like Danger. Secondly I actually shouldn't really try and read a used plug, the proper method is the new plug/plug chop method. In all my karting days a slightly richer set up gave a fatter, better power delivery etc. This showed up on the Laptop when we did the Data acquisition. But we also didn't use the low range like you guys do either!

Just as an aside ! I was pitting for my mate racing classics at Puky, he pulled his plugs in his 140HP Z900 and they where grey/white. We took the plug to Robert Taylor as Sean didn't want to muck around with it just on my say so alone. We ended up going a quite a few main jet sizes richer (white plugs scare me) and he said he lost nothing flat out down the straight but it felt much more solid out of corners. So richer even has an effect on the feel of a 4 stroke engine. I've had many an engine on the dyno tuning for the max curves, fine tuning carbs and going 60:1 in fuel etc. The dyno always said that was the best power output. But we always came back to 25:1 (in the Kart) with it a bit smoky during the pre-race starts etc. Every test Ive ever read more oil = more horse power (to a point). It simply delivered its power better and lost nothing flat out?

I'd really like one day to get Danger to have ago at tuning mine just to see how it feels. I know how to do it, but a lot of the tuning is in the seat of the pants of the tuner. Probably find out for a bike, its better! But gonna get him to do the suspenders first, all the power in the world is no good with the wrong springs in! I don't need anymore power till my riding technique is better! The way mine is, its quite forgiving so its OK for me. Its way not rich enough for carbon to be a problem. This new bike has helped the learning curve gonna try and do over a hundred hours this year if the old body holds up!
Find that thread Danger did or pm me your email address and I'll send you the copy and paste of it I did.


With plugs being $30 a pop.
Surly you could use the $8 BR8es ones instead of the expensive ones for this?? I had the first plug fail in years at Xmas and bought a cheapo BR8es (they didn't have any flash ones in Whitianga) it goes absolutly fine!

[camchain]

Interesting alright Danger. Thanks for the info, much appreciated. Some of that food for thought may lead to a little indigestion though, having shelled out for the JD kit.

That's a good heads up re needle clips/main jet, very relevant to my situation.

I read that part in earlier thread about your tuning without a main but didn't copy it into my notes 'cause I didn't understand it! How does the bike even run?

Was trying to avoid overcomplicating this but the following info now seems relevant re needles: The first two JD kits supplied were wrong. First kit was for 38mm carb, second kit was for 36mm carb but for 250cc. Was told 250 kit would be fine for my bike, right size carb etc.
I wasn't convinced so emailed JD who said jets were different in 250 kit (250 had some richer mains, up to 185 I think, and no pilot), blue needle was identical, but 200 red needle appareently slightly RICHER than one in 250 kit. - Quote JD: "The leaner needle (Red marked) is not the same. We found that the Red needle was leaner than what most EXC200 riders would want and we developed a Red needle that was not as lean." Unquote.

I guess JD could have made a mistake on that (ie red 200 leaner not richer) but doesn't seem likely, I just found it very odd that red 200 needle would be richer than 250. Seems to indicate they do optimise needles to some extent for each bike though? Didn't want email JD back without having a dig around first.

Very surprised at your small summer/winter changes danger. Just shows the whole thing can depend a lot on how well the main relates to needle. My take is it would seem to indicate that your jetting is very accurate?

Your lack of success with the JD needles for your RM is a bit discouraging. I couldn't compare my JD needles to standard as I only had the crazy NOZI needle that came with bike. Now thinking maybe I should get a standard NOZF just to compare, even if I only measure it to confirm if the JD needles I have are leaner all the way.

I'm guessing that when JD brings out a new kit they must make a series of similar needles in small progressions, then dyno test and pick the best one (or rather two). But how do you dyno test for altitude and temp/humidity though?

---Don't know if a mangina start is really needed but personally I'd like a kicker that doesn't start with your knee up near your jaw - and end shortly after with foot painfully slipping off like it did yesterday.
Cough, Ahem - My '07 delivers a very manly jolt when power valve snaps fully open suddenly---

::::::::

Plugs: Thanks guys. Just double checked and price was $22 for BR8E'G', is BR8E'S' the real plain jane? Initially I wanted Iridium but that was much dearer still. Liking the sound of cheaper plugs for testing.

S'alright Reckless, just very good info to chew over and it does help a great deal to get ideas from different sources. Believe me - I really appreciate it, and pretty sure I know where you're coming from. I promise I won't slag anyone off if when I pull the jug next time, I need to chisel a quarter inch of carbon off the piston!
Hell that's a lot of pep out of a Z900. I remember when the CBX 6 came out in '78 - Just over 100hp was a big deal.

P.S. Don't remind me about suspension. I thought I'd be getting onto that shortly, but money tree has no leaves.

Thanks again all (and to humai for going to shed to check!).

[tommorth]

this may be handy if looking at sudco needles
http://www.sudco.com/vol33/135-136.pdf

Ive got the older 38mm carb carbon reeds and a reed spacer
#6 slide 180 main, ddj middle clip and a 40 pilot but its not perfect mixing tts at 32:1

[Reckless]

Cham,
Br8es is the basic. I think two cost me $16 bucks retail from a mower shop in Whitianga at peak Xmas buying. Was going to get a flash EIX (or whatever they are) when I got back but I can't notice the difference, starts first time, everytime, goes the same? Just pulled it out seems to be running ok, bit black but nows not the right time to look even at a used plug.

Secondly My 03 came with the NOZE in it but I leaned it to the NOZF needle. So I have a NOZE spare if you want to try it Cham.

Also came with a a R1475J looks like a variation of the above but I've done a couple a ggogles on it and can't find anything about how it relates to the NOZ coding on the Ktm needles. Looks much leaner all the way through.
I know that
• 1st digit of MARK on OEM’s tells you the KEIHIN Part Number
• NEXT TWO DIGITS (2nd & 3rd) tell you TAPER angle.
• NEXT TWO DIGITS (4th & 5th) tell you DIAMETER of needle.
• LAST DIGIT (6th) tells you L1. ( leaness) J is about middle, simlar to E ( I think)

Anyone familiar with an R1475J or got a chart that converts NOZ needles to the Kiehin default numbering or Vice Versa? Danger???

Showing my Ignorance here LOL!!

[Danger]

The bike will run with no main jet until about 5/8-3/4 throttle (which you mark on the throttle with masking tape and a pen) and it will then fall on its face with a too rich condition. This is good because you now know what a rich main jet feels like as opposed to a lean condition. Until this position the needle jet and the jet needle are the restrictions to flow with the pilot circuit also adding to the mix. The important thing is you don't want the main jet to restrict fuel until the jet needle and needle jet are no longer a dominant factor (restriction). If your main was too small then it could restrict fuel flow before the jet needle and needle jet do so, so in fact your 1/4-3/4 range which is primarily controlled by these jets could actually still be too rich but the too small main jet is giving you a false impression and the main circuit will also be too lean. Fuel flows through the main jet before the needle circuit.

After you have set your pilot jet size first (because the pilot will also contribute fuel through out the range and is separate and additional to the other circuits, if you've ever had a blocked one you will realize this) and the air screw and you know that your needle jet and jet needle are correct with good engine response and no lags, bogging, coughing or pinging (you should not need to worry about the needle jet which is the jet the needle moves inside, they seldom need changing) and you know what a rich main feels like you can then fit a main that you expect is close but probably too rich and ride the bike. Then keep coming down one size at a time until you clear up the rich main jet symptoms. I like to find the main that is still too rich then come down one size from there.

Once the main circuit has been sorted with the other circuits you might need to fine tune the air screw.

You can now be confident on full throttle runs down 2km straight a ways (and I've seen seized bikes on these) and hard uphill climbs in the sand or what have you that your bike is not lean and going to seize or do damage.

A bike that is too lean will sound loud crisp and raspy and possibly ping or idle high on coming to a stop.

Over seas recommended jetting specs don't always apply with our different fuel and humidity at sea level etc.

Can't help you with that needle sorry Reckless.

[Reckless]

yep the way I see it in describing his tuning method Danger explains pretty much how a 2smoke carb works! We actually spend most of the time when enduro riding on the Needle and the needle jet (or Emulsion tube).
His method of leaving the main out to eliminate any interference or influence from that is a good idea.
He's quite correct the main doesn't have any effect until the needle lifts out of the emulsion tube high enough to get to the point the area that's left is larger than the area of the main. Unless the main is to small as he describes.

Major rule of tuning! If in doubt or got a flat spot or miss "always go rich first". no ones ever lunched an engine from being to rich!

Anyway if anyone is following this thread I've scanned the diagram from the Ktm manual on where each jet comes into the throttle position. If you read Dangers post in conjunction with this, it all becomes obvious!

[Brian d marge]

I can only add that I spend most of my time jetting for idle to 1/2 throttle ,,in fact I remember once forgetting to put the main jet in ,,,and didnt notice until I came in and made a jetting change ,,..

A cheap and cheerful data logger is the missus camcorder. taped to the bars recording the throttle ( I have a degree disk that slips over the bars , but tape and a pen work just as well.

You might be surprised how much throttle you use ....

I have got to do the same thing right now ,,,but its cold and gloomy out there today ,,,and I am making cheap excuses ,,,,,,,hense the length of this email :cold:

Stephen

[camchain]

Thanks Reckless and tommorth, but I need to be careful about over-thinking this whole thing! There are some charts etc. on KTMtalk about needle numbers and tapers, but I only skimmed it all. Too much for my feeble brain at least for the moment and too many options can lead to trouble. I should be OK trying a few different combinations out inside a limited range.

Looking at my handbook chart, that NOZE needle seems like it will be a fair bit too rich for my carb so possibly not worth troubling you for it for the time being, thanks though.

I'll have another read/ponder then email JD. I do find it a bit strange the JD needles don't have any numbers, does make it hard to compare. Even the colours seem back to front to me! Next change, I'll measure both needles top to bottom like I should have done to begin with. Next time I'm in shop, I'll grab an NZOF and buy or measure it, then I'll have some sort of baseline to go off.

Pity we can't ride on the beach anymore. Seems like a decent place for a jetting session. No bumps, corners or tree roots etc. Quite keen to try this wet line jetting, seems like a good way of avoiding being lean somewhere and not being able to pick it up riding.

:::::::::

Thanks danger. Been trying to get a better grasp of the way the different circuits overlap/interact. I did like the principle of this 'no main' when I first read it, seems an excellent idea to be able to isolate each aspect a bit more.

Sorry - more questions:

Just to confirm my understanding - the main ONLY comes into effect (unless main too small) at the higher throttle positions, no affect at all below this? Seems like my idea of main/needle relationship might have been way off.

Is the needle jet the part that is permanently staked into carb body where main jet screws into (from memory)? Carb parts diagram I just looked at doesn't show all. Edit: Whoa. info coming thick and fast. I've looked at that diag in handbook before and didn't really believe it. Now looking for carb cross-section pic to compare.

[Reckless]

Sorry - more questions:

Is the needle jet the part that is permanently staked into carb body where main jet screws into (from memory)? Carb parts diagram I just looked at doesn't show all. Edit: Whoa. info coming thick and fast. I've looked at that diag in handbook before and didn't really believe it. Now looking for carb cross-section pic to compare.

yes this is the Emulsion tube or some call it Needle jet. It is usually brass and is screwed down into the body of the carb. They can be changed but highly unlikely you'd need to if yours is standard. Yes the main screws into it.


Just to confirm my understanding - the main ONLY comes into effect (unless main too small) at the higher throttle positions, no affect at all below this? Seems like my idea of main/needle relationship might have been way off. .

Very hard to explain in writing but think about the hole between the needle and emulsion. Or the m2 area that's left at any throttle position between the taper and tube. As the needle rises this increases this gap/area letting more fuel in, So its a simple matter of measuring this gap.
So until this gap gets bigger than the area of the main it demands less fuel than the main delivers, therefore the main is only used as a hose feed and has no effect. I've drawn over the Drawing to help explain. Pretty primitive but I've tried to draw it as the jets relate to the power delivery. Its not till YY area gets bigger than XX area that the main has any effect. Simple process of area comparison or flow volume.

People get confused by the fact that except for the pilot/idle jet circuit all the fuel comes in via the main but its the measuring or metering effect of the needle in the tube that actually controls how much fuel is delivered to 3/4 throttle.

HAHA now we can talk about Power jets LOL!! Basically a tube from the bowl directly into the back of the carb!!

Shit now I gotta work late cause of bloody KB again!! I like these topics though! LOL!!

[cheese]

Man I find Jetting really confusing. I want to have a bit more of a play with mine, but scared of fucking it all up. Interesting reading here though guys. My bikes jetting is completely stock and I think that it should be altered cause of the aftermarket pipe.

Where do you think the best place to jet your bike would be? I'd be scared of doing it at woodhill cause too many meatheads ripping it up in the pits. Would thunder be an ideal place?

[camchain]

Uh-Oh. I've managed to turn this into a "*how does my carb work?" thread. Sorry.

i need to go back and read notes thoroughly. Some of the stuff I just read again about main jet is conflicting. Found this carb cross section pic. It's a CV carb but it shows the basics. Will delete if someone finds a more useful pic.

Edit: Ha. Posted almost at same moment Reckless. I haven't done any work at all today. I like what you did with that diagram - very clever. No bloody wonder I didn't notice any difference when I was trying to 'feel' a main jet change at around half throttle. 'Someone' (?) should run a jetting clinic day on a lonely beach somewhere?

[Danger]

The above pic is a diesel pig carb, see it has a fuel screw rather than a air screw.

Heres a few more that might help.

[Reckless]

Good diags Danger small point that your first one shows. There is some overlap or transition between all fazes. I like the GIF. Just need to work out how to slow it down.

I think we've done as much as we can on a forum.

Danger all the above doesn't really explain why we would change needles.

Given the bikes running OK a NOZE or NOZF might feel the same or very similar. I'd try a change it because the plug looked wet/dark or dry/light.
Do you do it entirely by feel?

[Triple X Motorcycles]

Hi Reckless

That needle is what comes in the bike when retricted to meet the ADR Regs so is an extremely lean needle. It should have been taken out and replaced with the NOZF 4th Clip with 162 main for 2007 200EXC.

Just a point re following the KTMTalk re jetting specs in that the fuel we have here in Godzone has a slightly lighter Specific Gravity meaning we do need to runslighty different jet settings.

On dyno runs and the six days in Taupo we came up with the following rule of thumb when looking at the jetting charts supplied by KTM. Älways use the next warmer temperature range jet specs to that of the actual current temperature range. This implies you will actually be running approx 5% leaner across the board. We have had zero problems when applying this to KTM and the bikes run well.

Hope this helps team. Give me a ring on 09 265 2135 if you want to discuss jetting for specific riding conditions as we do not have enough space in this forum to cater for everyone.

Also do not be afraid to play with the powervalve preload adjuster but make sure you know where you started and that point is always "Dimension Z" inthe spec sheet. Adjustment makes the bike a lot more rideable in the wet stuff. Cheers

[Reckless]

Thanks Steve And welcome to KB!

The NOZE & F needles I was talking about where in reference to my sons 03 bike I have. Came with the E and I changed it to the F.
Never had the R1475J in, and I wouldn't have tried as it looked far to big in the taper diameter and above. What you say makes complete sense thanks for that, now at least I know what it relates to, cheers.

My 08 has a 42 Idle, NOZH, 4th clip, 165 Main, 40:1. But I moved it to clip 3 to lean it a bit because I'm probably riding it lower in the revs than the guy that used to race it before. And it was a bit boggy down low. That made a big improvement to it, but I reckon there's more to be done there!

If anything the bike still seems a bit rich even though my needle is two steps leaner than you suggest for the 07?
Is the 42 a bit large, book says 42? Air screw is about 1-5-1-3/4 turns so that says the Idle jet is close.
Can we really compare it to the 07 because they completely revised the crank case flows, transfers, carb etc between those years didn't they?
Also I'm used to the 03 I had which kicks like a mule down low, but I don't want to make this bike like that, the 08 is much easier to ride and it climbs much better!

I'm pretty sure I could clean up the low/mid heaps (maybe try a straight taper set up) but it goes better than I can ride it so have left it alone till I get the suspension done. Also need a new side stand but want a stepped seat (heard they are really really good for body position on the bike), new tyre, sump guard, Radiator Guards, steering damper, ride 100 hrs this year! shit it never ends and my money tree has no leaves?

PS Steve do you have those better aftermarket side stands in stock!

[camchain]

Hmm. More useful info above. Seems like there is a bit more margin to sneak up to a leaner setup. Interesting quite a different needle in your 08 reckless. Thanks for the reminder on the diesel fuel screw/2 banger air screw danger. Back to the notes again, maybe I'll do some work tomorrow. I have a couple of different carb system diagrams saved now and they often show slightly different - but overall a much better mental picture is forming. Feels good to have my ignorance level reducing.
Kind of surprised now, that subtle changes in needles have so much affect. guess I'll soon be making some 0.05mm shim washers to raise needle for when sun goes behind a cloud. Cheese is right, where's the best place to do this stuff?

OK, sorry but here's another carb question that's always bugged me: Many years ago a mate seized his PE400 coasting down a long steep hill with the throttle off. Ever since I've been a bit paranoid and I give the throttle a few blips when in this situation. Guessing there's a similar risk when running wide open then suddenly shutting off gas.
I know the little holes on engine side of carb throat (one hole being idle) are supposed to take care of this by delivering a bit of fuel when throttle closed but how well does carb really handle closed throttle, but higher engine speed?

No need for stepped seat reckless - I find my standard seat is OK as long as I keep my arse off it. (Legs don't always agree with arse though, so I try to ignore them both)

[tommorth]

short answer when you close the throttle at high revs the pilot jet may not supply enough fuel/oil which not only lubes the crank but cools the piston piston gets hot because not enough fuel to cool it and expands lean condition also causes bike to run hotter and detonate this can cause bike to seize

[Reckless]

Simply pull in the clutch??
Honestly this situation wouldn't often arise!
High revs using the engine compression only to slow down, no blips between gear changes, no periods when you pull the clutch in to get around an obstacle and give it a blip to keep it going?? The thing must have been pretty lean for there not to be enough residue on the barrel walls as well.
Even when we do a plug chops we pull in the clutch.

Wouldn't sweat about it Cham alot of time has gone past since the PE400 days, probably even a cast iron bore, was it even water cooled??
You'll go crazy being that paranoid. If your worried pull the clutch and use those great Brembo's we've got!!

I am gonna try a stepped seat. If my mate who's been riding for many years, and is very good, really likes the one he's just got. I'm gonna give it a go! He liked it because it forced him to sit in the correct position every-time. I'm always sitting to far back, so sounds like just what I need. Lower seat might help when your stuck on a slope as well. Quite like the thought of sitting, in it, not on it, as well. Won't know till the money tree grows some leaves! Gonna spend it with Danger first hopefully he'll do me a good deal!

[warewolf]

Simply pull in the clutch??
Honestly this situation wouldn't often arise!
High revs using the engine compression only to slow down, no blips between gear changes, no periods when you pull the clutch in to get around an obstacle and give it a blip to keep it going??Top of the south is very steep and can have downhills that take minutes to get down (or at least seems like it???). So the question perhaps is, how long is a "long" downhill that would cause a problem?

In this situation I give the engine a rev (usually clutch disengaged) every 15 secs or so.

[Reckless]

I'm not saying its not possible, the theory is correct, but I did say "wouldn't OFTEN arise"
Jeepers we are talking about an old radial finned, air cooled, cast iron bore, round slide carb PE400 that blew up. Compared to our nikasil bore, water cooled bikes. Carburetion has come along way! Also oil technology is light years better. Those guys probably used the old castor based Castrol R.
Secondly you'd have to be in a low gear using engine braking alone with clutch fully engaged for long period of time. Hehe there's that word "Long" again. LOL!

The situation described would have to be not very technical either to be using engine breaking only for such a long time as to lean sieze it.

The fire breaks behind Whitanga where very steep I found that moving to 3rd or 4th was best. Kept the engine ticking over, with little load on it, without locking the rear. Bit like engine induced ABS. When you did lock it with the brake and it stalled it restarted really easy as soon as you released the brake. If you did feed it a bit of gas it didn't want to take off on you either.
Dunno if thats the correct method but it seemed to work OK??

A bit of fuel now and then never hurts and I usually go with the flow but you can't convince me on this one.:Pokey:

[warewolf]

I'm not saying its not possible, the theory is correct, but I did say "wouldn't OFTEN arise" :sunny: "Often" is one of those words, too :Punk: Several times each lap for 2-3 hours could count as "often". The terrain here is nothing like say Woodhill. The biggest downhill I know in there is less steep and quite short, only 1- maybe 200m.


Secondly you'd have to be in a low gear using engine braking alone with clutch fully engaged for long period of time. Hehe there's that word "Long" again. LOL!

The situation described would have to be not very technical either to be using engine breaking only for such a long time as to lean sieze it.They usually aren't very technical, apart from the steepness and lack of high-speed run out at the end, ie an almost-stop hazard so you can't just blast all the way down because you're gonna have to stop on the steep stuff. I do a mix of things, like you suggest with the higher gears and a little throttle, or clutch lever in all the way and brake... different things. Steep enough that you don't want to reverse a worn rear tyre because the lack of braking (or even downhill rolling) grip is highly noticable.

I am very intrigued by all this, especially your comments about modern engines. My 200 has been run on 40:1 premix, but I'd like to go 50:1 for less pollutants and less oil consumed. KTM says 40-60:1 depending on oil quality. Many people I've spoken to have more experience with road racing, they get the horrors even at 40:1, running 32:1 or 25:1. The reason for the latter is so they can safely shut the throttle at the end of the straight while braking into that 1st gear corner. If I'm going to go through the process of thoroughly checking and setting the jetting, I can change the oil ratio at the same time.

[Reckless]

I must say my opinions are my opinions only, you can all either take them or leave them. My experience has been in the Karting world Mainly with water cooled 125 engines on Petrol, Avgas and methanol, a few years ago now, but in the water cooled/power valve era. I have no formal mechanical or engineering qualifications. If you think what I say makes sense try it, if you don't, don't bother. Its only words on a forum!


:sunny: "Often" is one of those words, too :Punk: Several times each lap for 2-3 hours could count as "often". The terrain here is nothing like say Woodhill. The biggest downhill I know in there is less steep and quite short, only 1- maybe 200m.

I suppose it all boils down to common sense in the end!
I just didn't think it was a valid comparison blowing the PE400 to having to be careful on the tracks we ride here in Auckland on a 07 Ktm200. Camchain can be a bit over cautious as well?


I am very intrigued by all this, especially your comments about modern engines. My 200 has been run on 40:1 premix, but I'd like to go 50:1 for less pollutants and less oil consumed. KTM says 40-60:1 depending on oil quality. Many people I've spoken to have more experience with road racing, they get the horrors even at 40:1, running 32:1 or 25:1. The reason for the latter is so they can safely shut the throttle at the end of the straight while braking into that 1st gear corner. If I'm going to go through the process of thoroughly checking and setting the jetting, I can change the oil ratio at the same time.

We had karters running 60:1 (even me) with very lean settings etc. Even the dyno showed these settings to be quite good. But when on the track trying to push your fat butt out of a corner it just felt thin. Fine on the perfect race line & rev range but try and pass someone or make a mistake and it showed. I also read many reports/tests on high performance 2strokes back then and they all came to the conclusion more oil = more HP. I would hazard to guess this added up to better ring seal and therefore the piston was driven harder at each stroke developing more power. 25:1 did seemed to be the magic number as well. I personally don't think lean means mean in a 2 smoker.
In saying the above my 08 manual says 60:1 and doesn't mention any richer mix. My carb settings aren't to far away from the book so over all I suppose I'm quite rich. But it feels good, doesn't foul plugs, pulls like a 14 year old school boy & goes better than I can ride it, so I'm happy. I could probably go 50:1 as it is, but its only 5ml per litre I rather put that in and do less reconditions.
There's something to be said for not always changing things and just riding so you really get to know where it excels. We found this with our kids when karting. Take them to the track with the same kart for a few weeks and they got faster and faster, keep changing weight distribution, seat position etc etc to make it better and they never really got the hang of it. Hehe some fathers out there spent the whole time chasing the elusive "perfect" set up. We just smiled and beat them. Sooner or later you get faster by being fast yourself not by making the machine different everytime you get on it or blaming it.
Just my 2c??

[kezzafish]

Very interesting read, i've been following closely and have learned a lot from your discussion although it's all theory to me at the moment as i've never had a carb to pieces but i think i'm in a better position to have a hack if the need arises.

I had to pipe up and post something now cos' of your last comment reckless. I totally and whole heartedly agree that you must at some point just ride it as it is. It takes a lot of riding before you'll know exactly what adjustments will have a positive effect anyway. I've almost gone full circle with my suspension fiddling and although i learned something from it (which i believe is invaluable)... i basically ended up where i started.

Anyway cheers for the info and carry on regardless

[cheese]

There's something to be said for not always changing things and just riding so you really get to know where it excels. We found this with our kids when karting. Take them to the track with the same kart for a few weeks and they got faster and faster, keep changing weight distribution, seat position etc etc to make it better and they never really got the hang of it. Hehe some fathers out there spent the whole time chasing the elusive "perfect" set up. We just smiled and beat them. Sooner or later you get faster by being fast yourself not by making the machine different everytime you get on it or blaming it.
Just my 2c??

Couldn't agree more. Its funny you know, my bike has a few differneces to Sams CR and I found his one just strange to ride. But yes I think that if you're bike runs more or less fine, you will adjust your style to suit. The pros will know what a minor change in jetting would make, but as for average joe like me, if it all goes well, I just ride it (when I can!!)

[camchain]

Thread getting bloated - my fault for raising the seize Q. Good interesting subjects need new threads.

Yeah, the old PE400 seize-up is from a different era but mainly just an example to illustrate my Q. The only ride I've been on recently where I felt it might be an issue was the last 'A' option at Paparimu ride (the Mr Motorcycles one). Steep and very long. I just did pretty much what Werewolf described, quick clutch in and a throttle blip every now and then. Doubt much chance of a seize but just thought would be good insurance against extra wear from a dry bore, hot piston. As mentioned, being in the right gear has to be a good thing, no point in having the thing riiiiing-dinging all the way down.

Premix ratios - Reckless, I noticed the KTM ratio change in '08 and found it interesting. Maybe a political move for more environmentally friendly product?

The business of how much to tinker with a bike is a very good subject. There's definitely a lot to be said for the 'get things working and ride it approach.' I'm unfortunately in the 'always trying to improve stuff' side of the fence, and I love a well set up bike. Think I got this way from being an apprentice in a machine shop where accuracy was everything.

[warewolf]

I also read many reports/tests on high performance 2strokes back then and they all came to the conclusion more oil = more HP. I would hazard to guess this added up to better ring seal and therefore the piston was driven harder at each stroke developing more power. 25:1 did seemed to be the magic number as well.IIRC that was raised too - same reasons stated. Maybe I'll just stick to 40:1.:done:


There's something to be said for not always changing things and just riding so you really get to know where it excels.You haven't been talking to Mick Doohan, have you?? He puts a lot of his success down to his ability to tell the Honda development guys to eff-off, that he wasn't a test mule. He reckoned he could beat everyone with the equipment he had. If a lesser rider beat him by using a new development, Mick would then take it up. He even went back to the inferior screamer engine to mind-fuck the opposition, and they took the bait and wasted testing time trying to use that instead of concentrating on the better big bang engine.

Thanks for the input Reckless, very helpful.:niceone:

[Reckless]

Looks like we are pretty much on the same page really.
Very interesting the road boys came to a similar conclusion to us karters re Hp Vs oil mix and carb settings. Never knew that before.
If anything later oils are thinner and more slippery. Maybe we c should be using even richer mixes seeing as how we are not using the old thick oils??
When on Methanol I used Castrol MSSR which is pretty much straight Castor oil. Still have 4 litres in a pack here.
Smells good in the mower!

Mick Doohan I wish I'd seen him race!

[dammad1]

Premix ratios - Reckless, I noticed the KTM ratio change in '08 and found it interesting. Maybe a political move for more environmentally friendly product?



Exactly, be careful listening to the KTM manual when it comes to the mix ratio they are publishing these so that the bikes can meet the euro 3 emission regs, but that does not mean it is the best ratio for the long term health of your bike. I run 40:1 to be on the safe side and she runs sweet, changed piston at 86hrs and everything was mint.

[Reckless]

Exactly, be careful listening to the KTM manual when it comes to the mix ratio they are publishing these so that the bikes can meet the euro 3 emission regs, but that does not mean it is the best ratio for the long term health of your bike. I run 40:1 to be on the safe side and she runs sweet, changed piston at 86hrs and everything was mint.

Agreed my friend!! As stated, I run 40:1 as well. More oil more horse power :whistle: Interesting why you think they went 60:1, market pressure aye! Probably for the USA regulations as well!

Cheers mate hope you don't go to Aussy though!! To many bloody aussies over there.:buggerd:

[dammad1]

Agreed my friend!! As stated, I run 40:1 as well. More oil more horse power :whistle: Interesting why you think they went 60:1, market pressure aye! Probably for the USA regulations as well!

Cheers mate hope you don't go to Aussy though!! To many bloody aussies over there.:buggerd:

Yeah that is the only problem with oz, LOL but with the amount of kiwis going over there we may just start to take over.

[warewolf]

Mick Doohan I wish I'd seen him race!Used to watch and listen lots; spent 3 days trackside at Eastern Ck then the Island each year. Worked across the motorway from Eastern Creek Raceway, could hear the bikes during the January tests etc in some offices (through the air-con ducting) and in the "beer garden" of the cafeteria. Was standing against the fence at the hairpin when he got t-boned by Criville... that move hadn't been possible for 25 laps, and nothing changed on the last one... Criville simply rammed him.

Doohan used to practice like he raced; balls out. Do laps on this bike, then swap bikes and do more laps on the second bike while they changed stuff on the first one. Repeat. Then he'd come out and do full race distance at race pace to see how the tyres would last. Everyone else used to piss and fart around, do a few laps, rest 10-15 mins, do a few more, tour around parts of the track etc etc. He certainly put the work in and earnt every win. I think there's a lesson there for all of us! :Punk:

It helped that he held the throttle open further and longer than anyone else (easy to hear during practice), put the bike sideways more and laid bigger blackies. :first: