125-200cc 4 stroking vs lean plug readings

[edmoto]

I'm sorting out jetting on an 08 CR125 with TMX carb. The bike sounds and behaves like it is fourstroking. Plus lots of spooge. This tells me rich. It is worst at 1/8 to 1/4 throttle. It starts first kick, a little smokey at first but not too bad after bike warms up. Again, indications are a little rich. I did one change... dropped the clip on the needle from 2nd (up from bottom) to first notch (up from bottom... meaning tip is bottom), and the plug came out whitish on one side and grey on the other. This tells me lean. It was light brown before this one little change. I move the clip back up to 2nd notch from bottom, and plug goes back to light brown, but the raspy behavior is more pronounced now past idle and on top (1/2 and higher throttle as per my markings on grip as it relates to slide position that I checked). I move clip up to 3rd up from bottom and it gets a little browner.

I'm not asking for what to jet the bike at... oil/gas mixture, elevation, air density, humidity, my riding style... too much to expect for one perfect answer on a golden platter. But I am curious as to why my plug looks lean when I tweak richer (including turning the air screw from 1.5 out to 3/4 out)? It is also bizarre that the bike (bought used, good mechanical condition, motor has a few hours on it, no air leaks, air filter is clean and very light oil) was jetted to run at 3600' and I'm at 4800' and I believe I need to go leaner but the bike exhibits rich symptoms? I've ordered more jets and needles to start more testing, but is there some reason I'm missing for the "go richer but plug looks leaner" issue? For reference, I start the bike, one kick, on choke, immediately take choke off, start riding right away (no long idle), light throttle til the bike is warm, then do typical riding and a few speed runs up to 4th gear, then pull clutch, kill motor, then pull plug.

 

[edmoto]

From my first post a few hours ago I rechecked the carb. Floats were good, needle/seat was in good condition, and made sure no junk in the jets or fuel line up to the tank/petcock. I double checked my jetting notes and saw that today my air density and humidity were much different than anytime before with this bike. I've decided to jet fat on the pilot til I go out of range on the AS, then come back one size on the pilot. And go way fat on the main til I have the plug black (its never been anything other than light to medium brown in all my minor adjustments). I'll go counter the way I think the bike is behaving (too rich? four stroking?) and chase the plug for good color. I'd love to use my K&N air meter but it says the sensor will get false readings on oil mixed gas. So I suppose I posted and answered my own question! I'm still open to suggestions. And if anyone knows a boobtube or vimeo video that shows how a 2 stroke motor sounds going lean, I'd love to get the link. This is my first 2 stroke, and I'm finding my ear and knowledge from 4 strokes does not carry over well. Plus in my part of WY, there are no other Husky's that I know of to ride/meet/share/hear/tune with, so if the forum can tell me where to go for hearing what a "bawooohp" versus a "da da diiiing" or a "waaa ehhhinngg" as it relates to jetting sounds like, I thank you mucho.

 

[windsurf]

1/8th to 1/4 is pilot jet not the needle. Marking your twist grip is a good idea to see exactly what throttle openings are when you believe the bike is running poorly. Sounds like you are quite confused as to functions of air screw, pilot jet, needle and main jet. I am confused as to what you are trying to do? a plug chop is usually only for WOT ie main jet. Look in jetting chat to get an idea of specs for your bike and how to jet it.

 

[john01]

What is your current jetting? Main jet, needle, PJ, clip position, etc. ?

 

[edmoto]

Sorry about my seeming confusion. I've had a shop tech tell me I should be going leaner, an MMI graduate say go leaner, but my gut tells me go richer to get the bike to run better. I'm not upset or bothered by the bike... I 'd like to getting it running good and the bike handles better than any other bike I have. I've jetted an XR250, KLX400SR, KTM640, and VOR 503, because I'm at 4800' and ride up to 9000'. But it seems I am getting turned around backwards on the CR125.

This video, while the bike is NOT a Husky, and probably is a poor example of motor to motor comparisons, never-the-less sounds exactly like what the CR is doing now:

View: http://www.youtube.com/watch?v=0wzph3hL6EE


But then, even after jetting the bike a little richer, my plug goes from light brown all the way around to this:

I didn't have any jets for the CR's Mikuni in the ranges I needed, so all I could play with (for now) is the needle clip position and the air screw. Even though there is alot of spooge coming out the exhaust, per that video I decided to go richer even tho my elevation is higher than where the bike came from, and the advice of those two techs I've spoken with. Then I got that plug color per the photo I attached. It was light brown before that.

 

[edmoto]

Where is the sputter and raspy behavior worst? Per this graph seemingly at the transition to the needle and clip position:

 

[edmoto]

When I was moving the clip around, this is what I had in mind... going richer, but plug still came out leaner:

 

[edmoto]

Maybe my throttle position markings are off for the behavior I'm seeing/hearing. But I only had the needle and air screw to play with since I had no jets in the ranges I needed for this Mikuni. I think my main is off because that is what a plug chop can show, but I also was checking the plug without doing WOT throttles at low and slow throttle openings just to check for any change in color anyways. Turning the air screw in (richer) and raising the needle (richer) didn't change anything (I did the changes one at a time), and checking and rechecking the idle and resetting the airscrew did not yield any differences in behavior. I don't think the pilot is off given easy starts, no issues zinging the throttle in neutral with no load on motor. Per this guide, I need to look higher up in the circuits:

 

[edmoto]

You know what? I just realized I am a nerd. This is way too much thinking and not enough doing. I'm going to go rich, starting at the pilot and dial it back after checking idle/airscrew, then to the main, and maybe back to the needle to get black plugs and dialing it back to light mocha plug readings. I'm still open to suggestion, as it appears I'm about as clever as a bag 'o rocks.

For reference:
AS 1.5 out
Pilot 32.5
Needle 6DJ8-60
Clip 2 up from bottom (from tip)
Slide 3
Main 380

 

[Norman Foley]

I would double check for air leaks, carb inlet and crank seals.
For clarity, needle position is usually referenced from the top 1 to 5, as noted in your needle diagram .
You could start at stock settings....
AS 1.5
Pilot 35
Needle 6DJ8-60
Clip position 3
Slide 3
Main 400

Leaner 4 slide, may be an option at higher altitude.

 

[justpinit]

My bike four strokes at 1/8 to 1/4 but does'nt foul plugs or load up. I leave it that way because i believe that when the the engine is at higher rpm as when coming into a turn and down shifting the engine needs the the fuel a lubrication. When i come out of a turn and start rolling the throttle on it works great because the engine is higher in the revs.I think that the engine will lose to much lubrication w chopped throttle and high revs if thepilot jetting is set for it to run somewhat smooth when just putting around,wich is usualy when four stroking occurs.With you riding a 125 i would think it would be even more important.As far as the needle goes roll the throttle on coming out of a turn remeber how it feels than raise the needle one pos and see how it feels.It should'nt feel as responsive. If it feels the same raise it again. If it loses response or peppyness drop it back down a notch and leave it. I noticed you said you were already at the second from bottom notch so you may have to get a different needle.You can do the same w the main if you put a richer main in figure out if it feels faster or slower and how high it revs,in my experience to lean will rev really high and go flat quicker. To rich will not rev as high.If you get a black plug at wide open you are way way rich.The engine will tell you everything if you listen. I have a 2012 wr 300 at sea level.The idea is to find where it makes the most power the go a little richer.Sand and anything that loads the engine hard needs more fuel on the main. This is what works for me.

 

[justpinit]

Sorry about my seeming confusion. I've had a shop tech tell me I should be going leaner, an MMI graduate say go leaner, but my gut tells me go richer to get the bike to run better. I'm not upset or bothered by the bike... I 'd like to getting it running good and the bike handles better than any other bike I have. I've jetted an XR250, KLX400SR, KTM640, and VOR 503, because I'm at 4800' and ride up to 9000'. But it seems I am getting turned around backwards on the CR125.

This video, while the bike is NOT a Husky, and probably is a poor example of motor to motor comparisons, never-the-less sounds exactly like what the CR is doing now:

View: http://www.youtube.com/watch?v=0wzph3hL6EE


But then, even after jetting the bike a little richer, my plug goes from light brown all the way around to this:

I didn't have any jets for the CR's Mikuni in the ranges I needed, so all I could play with (for now) is the needle clip position and the air screw. Even though there is alot of spooge coming out the exhaust, per that video I decided to go richer even tho my elevation is higher than where the bike came from, and the advice of those two techs I've spoken with. Then I got that plug color per the photo I attached. It was light brown before that.

The only explanation i can think of is that it's so rich that the plug is'nt getting hot enough to burn any deposits on the plug,which is where the brown color came from. When the ground electrode gets hotter or colder the black "shadow" that is before the bend will move.Less shadow is hotter. More is colder.This is because hotter burns away fuel and oil deposits and because there is not as much left over after combustion.Colder of course is the opposite.Ive heard that the edge of the shadow should be on the bend.This is a plug when way to lean. I bought the bike brand new and this is how it was. I caused a nuked top end including cracked cyl. The dealer warrantied it.When i got it back togetther i did a quick plug chop and this is what i got. I went up two on the main and two notches richer on the needle.Ok so the pics ended up a little higher than i wanted but there up there^