Need basic carb help **** Updated with Plug Chop Pics

A reference for the PWK carbs...
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G22inSC
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Need basic carb help **** Updated with Plug Chop Pics

Post by G22inSC »

I have not tuned my carb in years and lately have been riding a lot slower since my 6 year old is now following on his little PW50. I do not have low compression and have no reason to think there are any mechanical issues. I don't have any real concerns with the way it responds to the throttle; however, I don't really know what I am looking for. I use to run 50:1 oil ratios (Amsoil and Mobil) and have recently begun to rethink that after speaking to several professional engine builders (rebuild on a KTM 50SX that will be a Christmas gift). I switched to Motul 800 and went back to a 32:1 ratio. I am not positive but I think my needle use to be one position leaner (#2 clip) in the past but I changed it to a little safer position to begin with. I have solved one problem...I would get a fairly good bit of spooge (but no real smoke) while riding since my carb was too rich. I didn't have any real spooge after yesterdays ride. It use to run down the outside of the silencer and there was no "trail" present at the end of the ride. My new problem is smoke. It will now smoke whenever I briskly twist the throttle and smoke a good bit at that. It does this in the low throttle settings. I know the fuel/air ratio was leaned by going to 32:1 and I am thinking the smoke is due to more oil being present. Is this correct or do you think maybe it is too rich on the pilot or needle (or both) and loading up on the bottom which leads to the smoke when the throttle is first twisted?

My current bike is a 2005 KDX200 with the following mods:

air box lid removed
ProCircuit pipe and silencer
misc. suspension and protection goodies



My carb is currently setup with:
42 PJ
155 MJ
stock needle in #3 clip
AS 1.5 out
NGK BPR8ES plug


Environmental factors:
1000' elevation
85 - 90 degree temps



Should I go one step leaner on the PJ? Try the #2 clip on the needle? What would you'll recommend?
Last edited by G22inSC on 06:50 pm Aug 23 2012, edited 1 time in total.
'05 Kaw KDX200 ('00 KX125 forks / '02 RM125 Showa "K2" shock)
'14 Yam YZ125(x) (oldest boy's)
'22 Yam YZ125X (youngest boy's)
'17 Yam YZ85 (soon to be FOR SALE)
'10 Honda Recon (wife's)
'08 Kaw KX65 (Sold)
'07 KTM 50SX Sr. (Sold)
'09 Yam PW50 (retired)
'97 Kaw KX250 (Sold)

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2005 KDX200 Bike Profile
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scheckaet
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Need basic carb help

Post by scheckaet »

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G22inSC
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Re: Need basic carb help

Post by G22inSC »

I've read that post I don't know how many times but still seem a little bit lost. I tried adjusting the PJ once again and I just don't know anymore. I warmed the engine and hooked a tach to the plug wire. I then turned the air screw out (from closed) looking for the RPM's to increase or remain constant when the air screw was backed out. If the highest point is above 2.5 turns out then install a smaller PJ. If the highest point is below 1.0 turn out install a larger PJ. With a 42 PJ the RPM's were still increasing at 4.5 turns out so I went down to a 40 PJ. With the 40 PJ the RPM's continued to increase (even at 4.5 turns out) but the increase at each .5 turn interval were much smaller and less pronounced. This makes me think I should go to a 38 PJ; however, I don't have one that small and I'm a little scared of going that small. Am I doing this correct? Does it sound right that I could safely install a 38 PJ. I just don't remember hearing much talk to using a PJ that small on here before.

What about the smoke. Am I just seeing this because I introduced more oil by switching from 40:1 to 32:1? My 6 year old wants dad to do a Hare Scramble with him this weekend and I really don't want to be throwing that much smoke all over the track. I think it makes me look bad since most of the other 2 strokes don't seem to have that problem.
'05 Kaw KDX200 ('00 KX125 forks / '02 RM125 Showa "K2" shock)
'14 Yam YZ125(x) (oldest boy's)
'22 Yam YZ125X (youngest boy's)
'17 Yam YZ85 (soon to be FOR SALE)
'10 Honda Recon (wife's)
'08 Kaw KX65 (Sold)
'07 KTM 50SX Sr. (Sold)
'09 Yam PW50 (retired)
'97 Kaw KX250 (Sold)

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2005 KDX200 Bike Profile
Fletch
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Re: Need basic carb help

Post by Fletch »

I think 40-1 is fine. That's what I run. What exactly is the current complaint besides smoke? Your current pilot/main #'s look fine to me compaired to what I see here. I wouldn't go to a 38 pilot personally, it seems to small. Have you done plug chops? You've got to be very close with the jets you have in there imo. Plug chops will tell you all you need to know. Ideally you would see fairly clean plugs, no fouling, little smoke, no spooge and great throttle responce. So what are you missing?
Fletch
89 kdx 200 with 99 rm125 forks
Brian
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Need basic carb help

Post by Brian »

I'm running a 35 pilot and 155 main and my bike runs great. I'm nearly at sea level.
KX 250, KDX 220, KDX 220, KDX 200, CR 80

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G22inSC
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Need basic carb help

Post by G22inSC »

Is my method correct? If I go too small on the PJ will I reach a point that when the air screw is backed out the rpm's will NOT increase? I have not been able to find that point yet.
'05 Kaw KDX200 ('00 KX125 forks / '02 RM125 Showa "K2" shock)
'14 Yam YZ125(x) (oldest boy's)
'22 Yam YZ125X (youngest boy's)
'17 Yam YZ85 (soon to be FOR SALE)
'10 Honda Recon (wife's)
'08 Kaw KX65 (Sold)
'07 KTM 50SX Sr. (Sold)
'09 Yam PW50 (retired)
'97 Kaw KX250 (Sold)

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2005 KDX200 Bike Profile
Fletch
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Need basic carb help

Post by Fletch »

At this point I would do 2 plug chops to see what the hell is actually going on with the pilot and main. Do you know how to do this?
Fletch
89 kdx 200 with 99 rm125 forks
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G22inSC
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Need basic carb help

Post by G22inSC »

I know how to do a plug chop, just don't have a place to do it anywhere close. Never thought of plug chop for the pilot jet. I thought it was just for main jets.
'05 Kaw KDX200 ('00 KX125 forks / '02 RM125 Showa "K2" shock)
'14 Yam YZ125(x) (oldest boy's)
'22 Yam YZ125X (youngest boy's)
'17 Yam YZ85 (soon to be FOR SALE)
'10 Honda Recon (wife's)
'08 Kaw KX65 (Sold)
'07 KTM 50SX Sr. (Sold)
'09 Yam PW50 (retired)
'97 Kaw KX250 (Sold)

Gallery

2005 KDX200 Bike Profile
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scheckaet
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Need basic carb help

Post by scheckaet »

it's just for the main mostly.
FYI you don't have to run all the way to 6th gear wide open, I've done going all the way to 5th and dragging the brake to put a bit more load on the engine.
Fletch
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Need basic carb help

Post by Fletch »

What about a 1/8th throttle plug chop for the pilot jet?
Fletch
89 kdx 200 with 99 rm125 forks
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Post by G22inSC »

Have a new game plan. I'm taking the day off from work later this week and going to Durhamtown to have access to some good trails. I plan to start with several plug chops using the drag strip and will get my main jet worked out. Then I will take to the trails and see how my clip position works and adjust from there. I think then I can hopefully get a handle on this jetting. If possible I will post some pics of the plug chops once I'm able and see what everyone thinks.

Where would you'll start the chops at...160, 158, 155, etc? I thought about starting at 160 knowing that should be overly rich to get an idea what the plug looks like. That way I would know what I was looking at as I leaned the MJ out. Sound like a plan? Lets hope this goes well.

Trying to get this sorted out before my first race this weekend. My six year old is racing his second harescramble and wants dad to join the fun. I just don't want to show up with lean jetting and possibly destroy the motor or too rich jetting and blow smoke and spooge on everyone. I have the feeling I will be pushing the motor longer than I have at any one time in the past.
'05 Kaw KDX200 ('00 KX125 forks / '02 RM125 Showa "K2" shock)
'14 Yam YZ125(x) (oldest boy's)
'22 Yam YZ125X (youngest boy's)
'17 Yam YZ85 (soon to be FOR SALE)
'10 Honda Recon (wife's)
'08 Kaw KX65 (Sold)
'07 KTM 50SX Sr. (Sold)
'09 Yam PW50 (retired)
'97 Kaw KX250 (Sold)

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2005 KDX200 Bike Profile
Fletch
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Re: Need basic carb help

Post by Fletch »

Sounds like a fine plan with a couple exceptions. I would do a couple pilot chops to see if there is any over richness there first. Then do the main chops. My reason is that the pilot if too rich may alter your main setting. 160 is where I would start (stock) and see from there as you say. I personally run a 158/48 and never foul plugs. This brings me to plugs. I use the stock heat range and would recommend the same for you. There should be a white ring down deep in the base of the ceramic nose even if you are running too rich. The band should be about .5-1mm IIRC.
Good luck
Fletch
89 kdx 200 with 99 rm125 forks
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Re: Need basic carb help

Post by G22inSC »

Fletch wrote:I would do a couple pilot chops to see if there is any over richness there first. Then do the main chops. My reason is that the pilot if too rich may alter your main setting.

I didn't think the PJ had much (if any) affect on a wide open throttle chop when checking the main jet. I will definitely keep that in mind. Thanks.
'05 Kaw KDX200 ('00 KX125 forks / '02 RM125 Showa "K2" shock)
'14 Yam YZ125(x) (oldest boy's)
'22 Yam YZ125X (youngest boy's)
'17 Yam YZ85 (soon to be FOR SALE)
'10 Honda Recon (wife's)
'08 Kaw KX65 (Sold)
'07 KTM 50SX Sr. (Sold)
'09 Yam PW50 (retired)
'97 Kaw KX250 (Sold)

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2005 KDX200 Bike Profile
Fletch
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Re: Need basic carb help

Post by Fletch »

you're probably right, I'd just want to be sure
Fletch
89 kdx 200 with 99 rm125 forks
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Need basic carb help

Post by hbgod »

you say its smoking. is it blue smoke(oil) black(gas) or white(coolant)
i doubt its white but its possible. if it is you have a leak somewhere allowing coolant into the motor
if its blue. well its a 2 stroke. its suposed to smoke. not rediculously but alittle
and if its black your running to rich. hope this help
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Re: Need basic carb help

Post by scheckaet »

"its black your running to rich"
or your exhaust is on fire...
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Need basic carb help

Post by rbates9 »

"is it blue smoke(oil) black(gas) or white(coolant)"

Mine smokes white and does not use any coolant? :roll:
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Need basic carb help

Post by hbgod »

rbates9 wrote:"is it blue smoke(oil) black(gas) or white(coolant)"

Mine smokes white and does not use any coolant? :roll:

errrr u sure it isnt a light blue. wen i say white i mean it looks like a ghost is coming out of your exhaust. and if its white u got water in your fuel then. bc thats what causes it to smoke white. the water in the coolant.
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Post by G22inSC »

Testing is complete; however, I am a little puzzled by the results. I think I need some expert opinions here. I performed all plug chops within 1.5 hours and a temp swing of about 5 degrees around lunch time today.

Plug chops were as follows: Ride over to dirt drag strip on old plug. Install new plug, kick engine over and immediately take off up to wide open 3rd gear. I was able to hold wide open in 3rd for about 5 seconds before simultaneously pulling clutch, holding down the kill switch and releasing the throttle to roll to a stop. Once stopped, pull that plug and reinstall the old plug to ride back to the truck to cut the threads and read the plug.

This is where my confusion began. I cannot see a difference between any of the plugs all the way from a 160 MJ down to a 150.

All plugs including the following MJs: 160, 158, 155, 152 and 150
Image

First Plug Chop (160)
Image

Second Plug Chop (158)
Image

Third Plug Chop (155)
Image

Fourth Plug Chop (152)
Image

Fifth and last Plug Chop (150)
Image

Why do they all look the same? I don't have any issues with the topend and I know the KIPS is functioning. Does anyone have any ideas or pointers?

I ended up with the following settings:
40 PJ
152 MJ
R1174K needle (#3 clip)
AS 1.25 turns out
Motul 800 at 40:1 (cleared up my smoking problem)

For the first time I can "put around" in first gear, grab a little throttle and loft the front wheel a few inches without the clutch or a little body english. I am a little rich (slight 4 stroking) between 1/4 and 1/2 throttle just before the pipe comes on. As soon as more throttle is given it clears right up and sounds great. Don't know if that is right but I have had a few engine builders recommend an little rich right before the powerband hits. I have not fine tuned the PJ yet and that may change a little once I do so. Just left the AS, PJ and clip position for all the plug chops. What does everyone think. Am I on the right track or is something here flawed? Help...race is in 3 days.
'05 Kaw KDX200 ('00 KX125 forks / '02 RM125 Showa "K2" shock)
'14 Yam YZ125(x) (oldest boy's)
'22 Yam YZ125X (youngest boy's)
'17 Yam YZ85 (soon to be FOR SALE)
'10 Honda Recon (wife's)
'08 Kaw KX65 (Sold)
'07 KTM 50SX Sr. (Sold)
'09 Yam PW50 (retired)
'97 Kaw KX250 (Sold)

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2005 KDX200 Bike Profile
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Re: Need basic carb help **** Updated with Plug Chop Pics

Post by CoronasAndChips »

It sounds like you finally achieved both your goals. What happens when you move the needle up and down from the middle?
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