Author Topic: Getting the jet needle out of the throttle valve?  (Read 27216 times)

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Offline mustangfury

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Re: Getting the jet needle out of the throttle valve?
« Reply #30 on: April 22, 2010, 10:09:18 AM »
If you disconnect the arm that pulls/returns  the rod  it shouldn't take more than a 8oz. or so of push pull to move in and out. 
Think of holding a can of soup in your hand.  The effort it takes to move the can up and down should be adequate to move the valve.
  Here's what I found on jetting specs:
  Oem  160 main                         FMF site 158 Main              (and using Bel Ray @32:1 )
           52 pilot                                        52 Pilot
       N1AL Needle                                     Stock needle
          3rd clip                                        3rd clip position   
         11/2 turns out on the A.S.                11/2 turns out

 You can be pretty safe on the FMF suggestions as they surely don't want you getting a new engine account they got your bike melted down.   This should be a good place to start.  you can replace the main with a 6mm socket by removing the 17mm plug on the bottom of the carb.
   Cut the bottom off a water bottle to catch the fuel from the carb bowl.
Having a clean air filter and fresh fuel also helps.
  Making one change at a time and keeping a log/notebook is also handy.   
If you can swing a service manual or clymer specific for your bike it will make things easier for you and they also have alot of other info to boot.     
  Tuck\o/

ok i checked which jet sizes were in the carb.

Main Jet - 170
pilot Jet - 52
throttle valve - #5
Jet needle clip position - 3rd

What is the difference in size?  Is it the higher the richer?

Also repacked the silencer... no difference.  Although the fatty pipe drained of oil so it definitely needed it.  not any less than i expected.

exhaust valve assembly works like a charm. Nothing wrong at all with it. Even revved up the engine and watched the governor arm move it. No problems.

Let me know what you think.  What should i start with or should i rejet at all?

Thanks

1993 KX 125

Offline mustangfury

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Re: Getting the jet needle out of the throttle valve?
« Reply #31 on: April 22, 2010, 12:00:45 PM »
also, my clymer manual says

Stock:
Main Jet - 168
Pilot Jet - 50 or (52 in Europe)
Throttle Valve - #5
Air Jet - 200 (could not find a number on mine?)

I'm sure this changes because of the fmf aftermarket pipe.
1993 KX 125

Offline Friar-Tuck

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Re: Getting the jet needle out of the throttle valve?
« Reply #32 on: April 22, 2010, 06:57:37 PM »
 Sorry for the delay Stang,
  I work for the Railroad and sometimes get stuck out of town a few days.
As for the #'s on the jets yes, the larger the # the more fuel they flow.
  So, from what you have right now, you are about six sizes larger than what FMF recommends with their pipe & silencer.

   The FMF and Pro circuit #'s are going to be conservative,   However logging your results will give you a definitive answer that your moving in the right direction and keep from doing any damage to your bike.
  Actually having oil pour out of the expansion chamber should give one cause to stop and think, and certainly having the silencer soaked after a few moments of riding.

 Cooler dense air will take or require more fuel.  Hot thin air requires less fuel.
  There is a pretty good chapter in the Clymer on the carb and jetting, look through that and see how it lines up with what we are doing as a litmus test for some peace of mind.
   There is a chart in there that recommends what main,pilot and air screw position to use as determined by the altitude, temperature and humidity.
  It may seem daunting now, but after the light goes on it's really not all that tough once you understand what's going on.
     If you're still somewhere between 60 & 75 degrees:   
 
    Would you be willing to get the 158 main (as per the FMF spec) and a new  or clean plug  and take an easy ride around the farm and check the plug?
We are not looking to do a full on W.O.T. plug chop until you feel comfortable we're operating safely.
  Working at one thing at a time will be easier to see the changes in running and make it quicker in the long run to get things dialed in.

  Let the bike warm up to where you can just hold your hand on the cyl and take an easy 10 min or so ride around the property at say up to 3/4 throttle. let the bike cool down and check the plug.   
   You should notice a significant change in the way the bike reacts and the plug will start to look better.
There will still be some smoking and residual oil migrating as you found in the expansion chamber.
  Not to worry, it will get better.
   Keep tabs on the weather conditions and let me know how the bike runs. It will become more important the closer we get to being really close to spot on.
   The first thing you should notice is the Idle will be higher right off the bat, so be prepared to either shut the bike down or be comfortable turning down the Idle when she fires up.
  Tuck\o/ 
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Offline mustangfury

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Re: Getting the jet needle out of the throttle valve?
« Reply #33 on: April 23, 2010, 09:40:38 AM »
ok i am going to order a bunch of jets. I found them for $2.50 a piece online plus shipping.  Since the shipping is more than the jets i bought all the sizes from 158 to 168 so i don't have to go back and order another one.  I just put a new plug in yesterday after repacking the silencer and it still has the same problem. I also have three more new spark plugs waiting for testing so i am set in that area.  Could a float level problem be causing it to be rich or does that just effect the level of fuel in the bowl?  I can check if it is at the right height, but i don't want to pull the carb again if i don't have to or if that isn't a very likely thing.  I will however check it when i put in a new main jet while i'm at it.

Thanks.
1993 KX 125

Offline bigbellybob

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Re: Getting the jet needle out of the throttle valve?
« Reply #34 on: April 23, 2010, 10:29:13 AM »
Quote
if you suspect gear oil getting sucked in past a bad crank seal you can do a simple test. with the bike running lay it to the left/ ignition side and give it some good healthy raps. note the amount of smoke and spooge. then lay the bike to the right / kicker side and give it some more healthy raps. putting the bike on the right side will put the seal in the oil and if its sucking some in you should see the difference in smoke out the exhaust. o and the gear box will need to be at the correct level before trying this. and have her up to temp. its impossible to properly evaluate jetting and such if the bike isn't completely up to temp.
did you ever try this

Quote
Could a float level problem be causing it to be rich or does that just effect the level of fuel in the bowl?

if the float r set to high or the need and seat aren't sealing fuel can flood in to the cases. but if it was that leaving the fuel on for a few minutes would flood it out right of the start and give you hell trying to start it. and if it started it would be really bad at lower RPM where you don't need all the fuel in the bowel
IF RIDING IS OUTLAWED ONLY OUTLAWS WILL RIDE

IF RIDING IS OUTLAWED ONLY OUTLAWS WILL RIDE

IF RIDING IS OUTLAWED ONLY OUTLAWS WILL RIDE

IF RIDING IS OUTLAWED ONLY OUTLAWS WILL RIDE

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Offline mustangfury

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Re: Getting the jet needle out of the throttle valve?
« Reply #35 on: April 23, 2010, 12:21:33 PM »
yeah i tried it a couple of times and did not see any difference. I don't think it is the issue but with the amount of smoke that comes out all the time, it still could be an option.  But, no, i did not see any difference tilting the bike one way or another.  I'm glad you told me about this method of checking it. I had been wondering how for quite some time.

thanks for the input on the float level too.
1993 KX 125

Offline Friar-Tuck

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Re: Getting the jet needle out of the throttle valve?
« Reply #36 on: April 23, 2010, 07:31:38 PM »
 Hey Stang,
  I think your making a good decision and yes like Big Bob says the float level will have an affect on your jetting also.
  There should be a pretty good write up in your clymer on how to set your float height if you need it and the float height should also be in there usually measured in MM.'s
Should you find you don't need several of the jets you bought you should be able to sell them at what you paid for them if they are still in good shape.
  If you set the float height when you put the carb together you shouldn't have to remove the carb again.
The mains are changed through the hole the 17mm nut bottom of the fuel bowl.
   Get yourself something like a small chip dip tub or the bottom of a plastic bottle and cut it to fit under the float bowl so  you can get your fingers to the drain plug and catch the fuel in the tub. It will keep from dumping the fuel on your case & chain or onto a rag. 
   Hang in there,
  Tuck\o/
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Offline mustangfury

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Re: Getting the jet needle out of the throttle valve?
« Reply #37 on: April 24, 2010, 01:19:36 AM »
i didn't think about changing them through the bottom of the bowl. that will make things a lot easier.

What size jet should i start with. i know it is best to work from richer to leaner to avoid engine damage but I also know i have a very rich jetted carb, so a change of -12 on the size might not be a bad thing.  Is changing from a 170 main to a 158 main a huge difference?

I guess i'm just wondering what the overall strategy is.  The strategy i had in mind was to go to 158 and see that the plug is a nice brown or if it is white i know to go up, then work our way up one jet at a time and go till we see oil then go back down one? 

...process of elimination. 

The only other way I thought of is elimination from high main to low main, reverse of the previous.  This sticks to the start rich and work your way lean, but the only reason i wouldn't want to do that would be because i don't want the silencer getting filled with oil and giving me bad readings out the muffler as i go lower or having to repack the darn thing every time i try a lower number.  Taking it easy like you suggested around the farm will prevent engine damage for that short period of time i ride while allowing me to start lean.

What fuel mixture should i run for this?  32:1? 40:1?
40:1 is currently in it. I would like to see it run 32:1 if it can though.
1993 KX 125

Offline Friar-Tuck

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Re: Getting the jet needle out of the throttle valve?
« Reply #38 on: April 24, 2010, 04:14:31 AM »
 Stang,
  Stick with one change at a time.
 Start with the FMF suggestions and we'll go from there.
The only change you will need to make is put in the 158 main.  The Bel Ray Oil ratio is the same, pilot air screw etc.
   You can run any mix ratio you want and still have a good running bike.
 Patience Grass Hoppa..  I know how hard it is to just keep the changes slow and one at a time. This will pay off in the long run.
   Take your time swapping out the main through the bottom of the carb so as not to cross or strip the threads, it really isn't so bad.  You will need a small (1/4" drive) 6mm socket or jet wrench.
  Here is a trick motion pro: http://www.motionpro.com/motorcycle/partno/08-0023/
      Craftsman socket :http://www.craftsman.com/shc/s/p_10155_12602_00934602000P
   No worries yet Matey!

 Yes also on the rich to lean direction.   Why take a big chance on ring, Or Worse piston seize.
    I don't want you to feel like I'm yelling or you're in the principals office.  Consider my suggestions and weigh them against what you have read in your clymer and what the recommended jetting specs from the pipe manufacturers are.

  There really is no magic #'s as the variables are always different and changing.
 Weather,elevation,wear and tear on the equipment etc.    Once we get you either to a point you happy with the performance, the only changes you will have to make jetting wise to stay in the ballpark is winter summer main jet.  an 8 minute process at most.
    The more critical you are with performance the more changes you will have to make.
As an example a Mechanic may change jetting on the bike he's responsible for through out the day as the relative humidity,temperature and track conditions change from morning 'till evening.
   
   Tuck\o/       
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Offline mustangfury

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Re: Getting the jet needle out of the throttle valve?
« Reply #39 on: April 24, 2010, 06:04:13 AM »
thanks i'll let you know how things go once i get the jets in and give er a test run.
1993 KX 125

Offline 500HORZ

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Re: Getting the jet needle out of the throttle valve?
« Reply #40 on: April 24, 2010, 10:01:03 AM »
Hey Friartuck,
Do you know the stock needle part number, and what is the slock slide number - it's on the bottom of the slide near where the needle comes thru - 6, and 7 are common.
I've got an 86 kx500 and a 99 PWK air Striker - it has a #7 slide and CGH needle, 50 pilot (may be a tad lean) seems to be working fine.  I plan to move to a 52 pilot and want to know what needle works best in your experience.
Also, have you done plug chops on the main jets, they seem a tad lean to me, I am running a 175 and the plug looks good, maybe a touch rich, ...
thx.
« Last Edit: April 24, 2010, 10:02:53 AM by 500HORZ »

Offline Friar-Tuck

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Re: Getting the jet needle out of the throttle valve?
« Reply #41 on: April 24, 2010, 03:14:59 PM »
500,
  Are you asking for a 99 500 PWK ?   Stock OEM is #7 slide,60pilot and a N82M 3rd clip.  I have been told that a CGG is a sudco/keihin replacement #.  I did not call sudco to confirm this however if you need one they can give you verification or another #.
 I have a #7 slide in my 500. 
   98% of the guys run the stock N82M and like it.  There is alot to be said about what kind of riding you do, how you ride, elevation and weather. 
   I have to tell you right off I am a chronic tinkerer.
   The bike ran great with a 170 main 2nd clip and a 55 pilot 55-60 degrees between 3500 & 4000'
However I had to ride consistantly faster than I was comfy with, and constantly shifting to keep the bike in what I felt was a good rpm range.....Soo... I started moving things around.  gearing, and then jetting.
 
   Some things to consider 90% of our riding is singletrack, hills and skidder trails.  3500' to probably 7000'.
 The fire roads we have here your lucky to get it WOT in third let alone 5th, and even the power lines are you are lucky to hit 3rd.  Yes my jetting is lean by any standard.
   However I am Old, Slow, and have no business riding this bike... But I love it.  I can crack the throttle and pop up the front end at will and I'm about 240-245#'s.  Lug it down in 1st now and I can almost idle along. Well, if I turn the Idle up a few turns I'm sure I could. 
  (I also have a bp7es plug in right now to see how that looks next ride, the 8 was rather wet last time out)
  If someone at or near sea level on a 70deg day tried to run this set up out in the flats the wouldn't get very far before the bike gave up. 
 I also have 13/51 gearing and it's actually the first time I had the bike in 5th without running along the highway.  I can now roll along at 10-15 mph through the trails at about 1/4 throttle.  Where as prior to this I was constantly shifting 1 2nd and sometimes 3rd.
   My best friend had a 99 500 and the only difference between his and my set up was he runs a 168 main and 14/48 gearing.    And he rides a heck of alot harder than I do. 
  I hate to keep refering to my old CR but I had the darn thing dialed in great for myself.  No plug fouling no spooge and the inside of the silencer was coffee ground brown.   
     I still am working to that on my KX and am getting close.
 
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Offline mustangfury

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Re: Getting the jet needle out of the throttle valve?
« Reply #42 on: April 28, 2010, 10:36:08 AM »
Ok i got the new main jets and put the 158 in.

I am now running:

Main jet         158
Clip position    3rd
Throttle Valve #5
Pilot Jet         52
Fuel mixture    40:1
Oil                 Bel Ray H1R

I rode the bike around in my 1/4 acre yard for about 10 minutes and kept it between 1/4 and 1/2 throttle most of the time with 3/4 throttle for a quick dash down my sidewalk here and there.  The cylinder got hot enough to where i could feel it was getting warm. It did not get super hot or anything like when i am going WOT but it just got warmed up.

At first the bike spat oil just the same but I definitely noticed a difference as the bike was warming up.  At the hottest point it was still spitting a little. Once i got it up to a so so temp I shut her down and wiped up all the oil so i could start looking while it was hot.  I started her up and gave her a short ride. There was not a lot on the rear fender, almost none on the swing arm, a few small drops on the rear caliper, and just a little accumulating at the back tip of the silencer.  After she cooled down I pulled the plug and attached pictures show what it looked like.



I know it was not completely hot yet but I don't go up to my uncles farm often and it is an hour and a half away.  My girlfriend has a 30 acre farm though and she is only about 35 minutes away so i am hoping to go up there soon to get the bike nice and hot (like tomorrow or sometime this weekend).  I don't have many places to ride where i live, so I like to take advantage of a big field to do tuning when i can.  I was just wondering what would be the next step to take depending on what the plug looks like after I ride her some more, and should i rider her at full throttle and get her up to a full ride temp for a bit seeing there is still oil on the plug?

Thanks. let me know what you think. Your help has been great!
1993 KX 125

Offline Friar-Tuck

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Re: Getting the jet needle out of the throttle valve?
« Reply #43 on: April 28, 2010, 02:19:09 PM »
 Hey Stang,
 Sounds like things are moving in the right direction.   By the wet, dark oily appearance of the plug, You still probably have  the oil that was previously in the crankcase working it's way through the engine.  It will take some time to get the whole system cleaned out.   
  Here is an article worth reading through on plugs:  http://www.strappe.com/plugs.html   
The same guy on oil pre-mix ratio:  http://www.bridgestonemotorcycle.com/documents/oilpremix6.pdf

If you can find the time to read through these two articles it would be great.

 I misunderstood about the pre-mix ratio. I thought you wanted to run 32:1.  that is what the FMF & Pro-Circuit bikes were running when they put out the jetting recommendations.    It is up to you as to what you want to run, just stick to one ratio until we get the bike sorted out.  After you are happy with the state of tune, then you will at least have a baseline to work off of.   Then we can pursue any other changes you would like.   

  The next time you get out to the farm to do some riding, I would repeat what you did around the house and get the bike up to operating temp.   Run her up to 3/4 throttle  for a bit and check your plug again.
  Make any pertinent notes we need to address, like "bike seems to bog at half throttle" or "doesn't pick up very clean"  "throttle response in the mid range is slow" .etc.
     By repeating the warm up and plug check you will verify we aren't hurting your bike and cleaning it out.
Next, =)
  Is there a stretch of road or field where you can run the bike wide open 30 seconds to a minute?     
What we are gonna try to do is after you got her up to temp is a plug chop.  Run the bike wide open for 30 sec to a minute and kill the engine.  Hit the kill switch and pull in the clutch. 
  What we want to accomplish is see what the bike is doing wide open.    By not letting the bike Idle or decelerate using the engine compression we won't wash off the evidence on the plug.
  Tuck\o/   
« Last Edit: April 28, 2010, 03:13:56 PM by Friar-Tuck »
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Offline mustangfury

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Re: Getting the jet needle out of the throttle valve?
« Reply #44 on: April 28, 2010, 11:09:17 PM »
I do want to run 32:1 but I still had the 40:1 in the tank at the time. when i take it out to the farm i will put the 32:1 back in it.

I do have a section where i can run it wide open for 30 seconds. I will be going to my girlfriends today so I should be able to try it out.

The bike overall ran a lot better yesterday when i tested it.  The throttle was a lot more responsive through every powerband.  This is definitely helping.

Also, the weather conditions yesterday were 60 degrees, no precipitation, low humidity.

The forecast for today is 69 degrees, no precipitation, 30% humidity.

How should i set the idle?  Should idle be set as low as possible but steady, high as possible, or in the middle?  I have the air screw at 1.5 turns out like stated and that works good. I was just wondering where to set the idle screw at.
1993 KX 125