Maintenance & Technical > KX250 / KX125
Getting the jet needle out of the throttle valve?
mustangfury:
--- Quote from: Friar-Tuck on April 16, 2010, 06:06:54 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/
--- End quote ---
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
mustangfury:
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.
Friar-Tuck:
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/
mustangfury:
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.
bigbellybob:
--- 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.
--- End quote ---
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?
--- End quote ---
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
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