Jetting

[Spencer]

Just a suggestion to those that are new to jetting their carbs. I HATE!!!!!!! jetting, I get a headache and often miss days of work due to stress related illness just thinking about it. Actually doing it causes uncontrollable eye twitching and nausea coupled with a deep depression and crankiness. A trip to the dentist is a viable option to jetting on my scale of enjoyable things to do. The problem is, If your not doing it your missing out. My new ride is a 2002 KDX200 and I've gone the route of the gnarly torque pipe and turbine core silencer, boyeson reeds and twin air filter with air box mods. I ordered up a good selection of brass and took off to a large open area to get the beast sorted out. (Heres the tip) DO NOT TAKE JETTING RECOMENDATIONS AS FACT!!! They may be a great place to start but ALWAYS check the results. I installed what was recomended to me (155 main/45 pilot) and the first plug reading at WOT was whiter than the plug came out of the box with a corresponding dead duck hole in the throttle response off bottom. Guess where I ended up a dozen plugs later....... The stock jetting with a clip position leaner on the needle and I'm not sure that was necessary. All told the biggest gain came from playing with the air screw for an hour. I now have enough brass to make a pretty neat necklace and enough needles laying around to make me look like an amateur accupuncturest and I'm running around with what Kawasaki originally intended. Go figure. The good thing is now that I've had so many WRONG jets in the thing and felt the results, I pretty well know a jetting problem when I see/feel it. Maybe that would be a good jetting lesson huh? Take a perfectly well jetted bike and keep screwing jets into it to see the results. ;)


Opinions vary
just my 2 cents

 

[canyncarvr]

While it is odd that your experience is different from practically everyone elses (and thus cause for some concern...like, where is the leak?)

...your point is well made.

ALWAYS check the results

Amen!!

I pretty well know a jetting problem when I see/feel it

You have to realize that is a valuable piece of knowledge.

Consider that most riders (it seems) do NOT have that advantage.

Surely you'd rather have it than not.

Congratulations on getting the job done!!

...sorry 'bout your haid! Hope you feel better!!;)

 

[jaguar]

Maybe people wind up with different jets because they are looking for different things from the powerband. I've got my main set almost too lean but I love how it winds out very clean.
Different strokes for different folks.

 

[andy jackson]

i have a 2002 kdx,& r going 2 install a gnarly woods pipe , running on race gas as keeps engine & pwr valves spotlessly clean, hence no stripped gears.wot jetting would anybody suggest to start with & i want 2 retane airbox lid 4 water proof reason"s,& holes drilled in it have been sujested , but how many , wot size & where seem"s 2 have been left out.also have noticed rear suspesion sag after some use.wot static sag should i run?i used 2 have a 89kdx200 & a 10mm pwr vavle spacer was sugested as a bottom end boost.Is this mod still current 4 2002 model?thanks 4 any help . happy kdxing!cheers andy.

 

[Mac]

I think your wasting money with race fuel as it is not needed on your stock kdx and has little to do with keeping yur power valves clean. Choose a good premix oil, mix around 40:1 and proper jetting will keep the top end clean.

Many of us either remove or drill half a dozen 1/2" holes in the airbox lid with no water problems.

Adding a torque pipe, drilling the airbox lid and rejetting will make a huge performance difference in your bike but you still won't need race fuel.

Can't answer the rest of your questions because decoding your post was making my eyes hurt.

 

[jeffw]

Great thread, lmao:) Good info, and entertaining at the same time...

 

[canyncarvr]

Gee...mac's not just kidding, either..ow!!

I could hold on for another sentence....or whatever...

Holes are drilled in the rear of the cover..the raised portion. Holes vs: removal allows you to keep your arcy-sparky box where it is (bolted to the cover). Also cuts down on the 'HONK' (described by one rider as sounding like someone killing a duck ;) ) you get with a quick flick and no cover. Will help with water resistance somewhat, too.

sag: Varies with rider intentions, but 100mm is a good place to start (race sag). Free sag follows from that correct setting. You don't set free sag..it's just what you get after you set race sag right. But, it should be about 12-27mm. IF your free sag is 'short', it's an indication of a too soft shock spring. If it's too 'long', that indicates a too strong spring. Oh..I'm assuming 'static' sag to be free sag. It's what you get with ONLY the weight of the bike. Race sag is YOU on the bike with all your gear, measured as amount the bike drops from a TOPPED out, or completely unloaded position.

Mac is right about the race gas. A waste..maybe even a detriment. Race gas burns more slowly that pump gas. That's a requirement in a hi compression engine. A stock kdx ain't one-a those! What passes for hi octane these days (92-93 or so) is fine! Exceeds spec, even.

where's my advil..........

 

[andy jackson]

thanks 4 replys will try as suggested.cheers andy.

 

[Bryan Kimsey]

How clean does the bike run off the bottom, and I mean The Bottom, as in just off of idle. My daughter has an XR50 and is not real fast or agressive on it, thus I spend a LOT of time in 1st gear bubbling along behind her. Right now my '96 KDX200 runs great at 1/4 throttle on up, but right off of idle, it sounds kind of like a tractor. Messing with the air screw from 1.5 turns to 3.5 turns doesn't make much difference.

So, does your well-jetted KDX burble at 1/64 throttle ;) or does it run clean there?

 

[Gladiator]

That is a good description "Right now my '96 KDX200 runs great at 1/4 throttle on up, but right off of idle, it sounds kind of like a tractor" mine does the same thing and i tried several differnt jets and settings. Suggestions anyone?

 

[andy jackson]

yep,ive a suggestion,tried it 2nite.Drop ur needle circlip down towards the pointed end 1 notch.Also have been told boysen reeds make a improvement 2 bottom power etc.Will know after as have ordered some & installing 2morrow.

 

[canyncarvr]

How clean does the bike run off the bottom, and I mean The Bottom, as in just off of idle. ...right off of idle, it sounds kind of like a tractor

If it's a flat Whaaa sound, it's lean. If it burbles, it's rich. Don't know what kind of 'tractor' your referencing.

If your AS doesn't have an effect, something else is out of whack. A too large main, too small diameter needle or a needle too high in the needle jet will render the AS useless or at least quite ineffective.

A 'C' series needle (1.5º taper) works as well as it does partly because the diameter spec of the needle is way down in the needle jet due to the taper 'start' being later (cuz of its faster 'slope' than the oem 1.25º). That allows the pilot/AS circuit to be more effective.

Keep in mind!!!..

..Drop ur needle circlip down towards the pointed end 1 notch

is making the circuit RICHER because you are raising the needle.

Nothing wrong with doing that...but keep 'raising the needle' with 'more gas' and 'raising the clip' with 'less gas'.

My bike couldn't be better right off the bottom. As low as you want to get, as slow as you want to go, as 'up' a hill you want to be on...it's instant, right now, immediate, quick, fast....no hesitation, even.

It tractors alright...guess it just doesn't sound like one.

 

[Bryan Kimsey]

>>If it's a flat Whaaa sound, it's lean. If it burbles, it's rich. Don't know what kind of 'tractor' your referencing.

Mine burbles. I suspect my main is too rich for my altitude- I'll have to go check to see what I have, but I remember stopping at the rich side, plus the plug is a little more chocolate than tan.

The "tractor" is a Ford N-style- you know: "chug-a-chug-a-chug-a". And it ONLY does that when _cruising_ just off idle. Acceleration off idle is just fine. Ever follow a rather timid 8-year old girl on an XR50? You'll be tempted to add a 60 tooth rear sprocket to your KDX....

 

[Bryan Kimsey]

Oh....meant to mention: altitiude is 6,000'. Bike has an FMF Torque and opened up air box.

 

[canyncarvr]

How about an 8 year old girl on a sportrak90? I do that.

Plug color can be misleading. Your main could be fine (WOT plug chop color checks) and your needle diameter or clip could still easily hose the bottom end.

If 1.5 to 3.5 turns out on the AS doesn't make a difference, you're most certainly way to rich someplace else.

CDave has an elevation/temp jetting grid chart on his website:
http://justkdx.dirtrider.net
6000' will certainly figure in on your jetting AND your overall performance. It be t-h-i-n up there!

If you're still running the stock needle, try it @ #2 clip (second from blunt end. You would be DROPPING the needle if it's in the middle position now).

Don't wish to oversimplify things. Don't know what you know, what you don't. I'd prefer erring on the side of simplicity.

You're pilot should be down in the 40 range...maybe even a 38 with the -35 pipe and 6000 ft el.

Try a 'G' series plug...like BR8EG. The fine wire helps a LOT on low-end, chugging plug load-up tbls.

Everything else OK, you should be able to (example) chug around with the XR @ 2+ turns out on your AS most of the afternoon, turn it back to 1.25 turns out and get response good enough to pull as hard as you wanna! 1/8 turn on my AS makes a difference way up to 3rd gear pull.

Cheers!!

 

[Bryan Kimsey]

>>Don't know what you know, what you don't.

I know quite a bit- been riding since 13 and I'm 40 now, have done all my own maint (top ends, etc., etc.) and am very mechanically minded. Most of my experience is with 4-strokes, though, this is only my 3rd smoker.

Needle is stock, on the top clip (full lean). Pilot is 2 steps lean from stock, where ever that is (I forgot), main is 1 step lean. Again, it was WAY rich when I first got it and ran pretty good there, so I just stopped until I got a feel for the bike. I've got a feel for it now, and am ready to work on the jetting.

1/8 of a turn! Really! It's THAT sensitive- definitely something not quite right on mine. I'll get to work. Thanks!