jetting to rich?

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krazyinski
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jetting to rich?

Post by krazyinski »

2000 fresh KDX 220 engine built and modified by Fredette carb bored from 33mm to 36mm FMF Gnarly woods, gold series pipe turbine core 2 silencer. 160 main 45 pilot r1173L needle on 3rd from the top,running 50-1 goldenspectro 93 octane pump gas, at 700ft, temps in the 80's does this seem to rich ? I just traded a thumper for this bike so I don't have a lot experience tuning the two strokes. and the kips valve throws me off to. it has a flutter on the top end in 1st and 2nd before the kips opens up and gets poor mileage on tight single track were your on off the gas. plug color is tan on the electrode and oily around the thread ring or housing. a little spooge out the pipe and spots on the back of my Jersey. lid is off the air box, well as far as telling when the kips opens you can feel and hear it with the kips closed it runs like a four stroke as far as having tractor like torque and being able to short shift with out loss of power and when it opens you can hear the pipe get louder in the expansion chamber and the power comes on like a MX bike gone mad with arm stretching pull. so with the kips open it runs like a banshee with it closed it pulls fine as long as you short shift cause the top end 5/8 throttle with the kips closed tends to flutter blip the clutch to up the revs the kips opens and yeeha! shift up and no more flutter. almost like running in to a rev limiter on a four stroke. If I am in to a big slippery corner when that I want to run fast and steady this is were I notice the flutter cause I have to shift up or blip the clutch to get past it. running 13/49 sprockets 2nd gear role on the gas fine till you get 5/8 to 3/4 throttle the it starts sputter even if you give it full throttle no response and it will smoke more like its running too rich, all it takes is a blip on the clutch and it jumps to life.
what I would like is a flutter less transition. this is the only time it does any thing weird. I am alitle lost here any opinions or help would be great. the guy on thumper talk forum said it was to rich on the bottom and said I was hearing rich low end to a lean high end and should not be hearing the kips open. ????
Last edited by krazyinski on 07:54 am Mar 21 2006, edited 1 time in total.
2000 KDX220 FRP Ported,plated cylinder,milled head, FRP bored carb, V force 3 reeds, FMF desert pipe, 10oz FWW, 98 KX forks and oem shock re valved by Pro Action, hyd clutch, fastway pegs, tall seat foam, gripper cover, 29" CRhigh mini bars, Cycra brush gaurds.
Rhodester
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Post by Rhodester »

Well, I'd say that it's a good thing that the guys at Thumper Talk are riding thumpers....

My guess is that the "flutter" that you're talking about is what we'd call 4-stroking. 4-stroking is a natural event when you're cruising under a very light load and a small throttle opening. When you're heavy on the throttle and it's 4-stroking then you're running significantly rich at that throttle opening range. You can lean the main jet/change or lower (raise the clip) the needle and experiment for starters. I can always and easily tell when the kips opens/closes, however, the power should be a fairly smooth transition at that point. If my bike is a little flat or hesitant with the power just before the kips opens (6000 RPMs) then I need to go 1 richer on the main (assuming that I have my needle worked out). If I was 4-stroking (or other rich indicators) just before the kips opened then I'd go 1 leaner on the main. That's accelerating at WOT as I passed that 6000 RPM point. BTW, make sure your filter is clean and PROPERLY oiled (excess oil is well squeezed out).
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Post by krazyinski »

AA! HA! thats what I was thinking so I ordered a 155 and 158 main I will proubly drop in the 155 main sense it will be reaching temps in the 90's soon and lower the needle. then go from there.
It runs so good I wasn't sure if it was supposed to flutter or not but I would rather have a smooth transition. thanks much .
2000 KDX220 FRP Ported,plated cylinder,milled head, FRP bored carb, V force 3 reeds, FMF desert pipe, 10oz FWW, 98 KX forks and oem shock re valved by Pro Action, hyd clutch, fastway pegs, tall seat foam, gripper cover, 29" CRhigh mini bars, Cycra brush gaurds.
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Post by fuzzy »

Don't overlook the pilot as it could still be too rich. You may need a needle profile change to cure where your bike is '4 stroking.' 4-stroking can be cured at all throttle positions when jetted properly, and this may mean LOTS of anally spent time with different needles, etc.
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Post by Rhodester »

I worked with needle ranges from xxJ to xxQ trying to clean up that off idle no load 4-stroking. I could indeed decrease it, but not without very negative side effects to other ranges of the bikes running. I did this while also decreasing my pilot clear down to a 38. I've come to the conclusion that this no/light load 4-stroking is part of the nature of the beast. My last jetting with the PWK35 was 152, DEK/3, 42,#7TV, AS 1 1/4, and the lid on the air box. This is with a -35, Q, RAD valve, elevation 2600', and 80+ degrees outside. It was slightly rich on the pilot (for off idle response purposes), crisp on the needle straight section, and a little rich on top to counter a lean hesitation/flat spot when wicking it. I have just recently installed an RB Air Striker with the following jetting: 152, DEK/3, 40, #7TV, AS 7/8 out, air box lid on. I'll give a report on how it performs when it warms up enough for me to get into some real dirt to test things out a bit.
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Post by fuzzy »

My RAD valve is hard to tune also. I think it's a pile really....Stock or DF are the way to go. THe RAD valve will provide more peak power, but with a sacrifice.
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Post by canyncarvr »

If my bike does not 'flutter' (likely what Rhodester says...4-stroking) on pretty much any carb circuit under no load..that makes me very uncomfortable. I know I'm too close to a bad edge on jetting.


re: 'the power should be a fairly smooth transition at that point' (speaking of the KIPS transition)

That's an important fact commonly overlooked in terms of jetting, too. A large 'hit' in the powerband is a good indicator that the bike is recovering from a poorly jetted throttle range to one that works well (or better anyway). That is not to say pipe-tune and its supercharging effect are not/shouldn't be readily felt on your fanny.

Hence: 'it starts sputter even if you give it full throttle no response and it will smoke more like its running too rich..'

Because it is. That may not be due to the throttle range you're IN, but the plug loading that happened in the throttle range you WERE in.

If you're looking for good response (who isn't?), the 'B' slope needles won't get you there.



Rhodester:

Probably old hat that you know about...but...

Don't discount the DEK@-4 until you try it. DO find the Second Sweet Spot on the AS. It's there, guaranteed. It's out about 2 1/2 turns..fine tune by 1/16ths.

Your 42 is probably too high (like fuzzy said already. I'm merely chiming in agreement)...especially with a -35.

You're a 'tester'....some things (like the SSS) are easy to overlook though, cuz...'Why go way out there?'

Because it works better than anything else you will come up with!!

I think I gave my radvalve to someone that wanted it. It wasn't worth the cost of postage.......more of my $.02! Oh goodie!!! :roll:

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Post by Rhodester »

Brad, thanks for the reminders. The RB Air Striker came with a 40 pilot and from what I can tell it definitely won't be too lean. I certainly will try DEK/4 as well as search for the SSS. Maybe my next mod will be the DFIII.
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Post by canyncarvr »

**hijack** ..pretty much...

I generally run a 40 in colder temps. Currently have a 38 in, but for a reason other than throttle response. I'm working some other problem.

I have asked Mr. Black about the SSS part..the hows and whys of it. He thinks at that amount 'out' that some other circuits may be brought into play that mask the pilot circuit's effect (He does clean-up on the pilot circuit passages at least. They have been known to have casting goobers left in them that have given some guys fits trying to sort out). Whatever causes it, it's a huge treat!! Throttle response in the bottom 3/8s range is improved (Again! Summore!). Where the biggest benefit shows is mid-throttle in 3rd gear! It's a lot of fun!! I'm not the only one that's sorted it out..AND been very happy with it, too!!

I cannot say enough good things about the DF3. Heck...I got DF3s in TWO Banshees at home, too (uh..that's four cages!!)! Yep...Mr. Black's carbwork, too!!

Hate to bring THIS up...but there is NO reason you can't run a -30 with the Air Striker and a DF3. Every bit the bottom of the -35..just more fun on top!!

Besides...the -30 sticks out so far..it gives you a chance to really crunch it some, too! Now there's a gnarly pipe for 'ya!! :wink:

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Post by Rhodester »

If I end up getting a DFIII I'll throw my -30 back on and try it out. Sounds like some fun!

I've been contemplating the idea of getting over to your part of the world to do some mountain type riding the next time a group ride comes up. Keep me informed (now a total hijack!).
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Post by m0rie »

A couple of us are getting together sometime around Memorial Day weekend for a ride around Ski's. You should come on down.
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Post by fuzzy »

Rhodester, you should love that compared to the radvalve. You seem to have an above average jetting ability so tuning should be nothing but a thing...
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Post by canyncarvr »

What fuzzy really means: 'The RadValve is a totally useless piece of crap!'

Actually, he very clearly STATED that already. I just repeated it to make sure his point wasn't overlooked! :wink:


Ski has promised all comers the ride of their lives this upcoming MDay. You might as well come on down!!! (Well..and a bit over!)

Updates are in the group ride forum.

Ski will probably have a few KXs lined up for sale..... :wink:

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Post by fuzzy »

:lol:
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'94 WR 250 Always a project
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Post by Rhodester »

I'll see if the phone will let up enough for me to get out of town (I'm a business owner :roll: ).
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Post by skipro3 »

The more the merrier!!

Right now, there is just a bit of snow on the ground.

Image
This is my truck outside my shop door at work.

Image
this is a shot of me driving to the powerhouse to work that same day

Image
And this is me coming back to the shop at the end of the day
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Post by Rhodester »

Are you sure all of that will be gone by late May?!?
.....and if it is, will it be like a mud bog where I get the fun of being wet and freezing my butt off?!? :cry:
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Post by GS »

Hey! That looks like fun!! It's just raining around here (Vancouver, BC)

:cry:
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Post by skipro3 »

By late May we will be spacing the riders 5 minutes apart to keep from choking on the dust. Gotta love that California sunshine!!!
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Post by GS »

Dust? What's that? :blink:
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