What A Great Day!!!!!!!

[Brian]

Boy am I relieved. Got home from school today to find my graphics that I had ordered waiting for me at the front door. Rushed in, put them on, and mounted the shrouds back up. Boy does it look good :) I armor-alled the bike to take some pictures to put in my gallery(took 26 pictures, only 4 came out good because of my cheap-o digital camera). I did get a few pictures, nothing much, but they are up if you'd like to see them. Later when my dad got home, I talked him into helping me take the carb apart to see how it was jetted(bought the bike used). As many of you know, I've been complaining lately about the pinging and knocking sound my bike makes, and thought it was jetted too lean because of this. We pulled out the jets, to find they were the stock specs. My dad has been riding for around 30 yrs.+, so he has a surplus of jets. I found what C. Dave recommended on JustKDX(way leaner, wich I thought would make matters worse, but put them in anyway for the off chance of a miracle) wich is142/145 main,(I put in a 148) 42 pilot, and needle in second from the top. I took off down the street and was dumbfounded. It used to take 5 minutes to warm-up and clean out, now only a few hundred feet. And the pinging/knocking is totally gone. Throttle response is now quicker and crisper, and overall, semms to respond better everywhere. No odd noises (other than the typical KDX rattles etc...) All in all, it has been a very good day :)

 

[Brian]

Uh-oh. Just checked JustKDX again and found out I rejetted my bike to 220 specs :( Here's the recommendations:
200 main=155
220 main=142/145


Right now I'm running the 220 settings, wich is quite a bit leaner than the 200's. It runs much much better(no surging, etc..), but is this too lean??? Now I'm worried It might cause some damage like seizure :( Please Help!!!

 

[gooby]

dude i hate to offer jetting for fear of being blamed by someone that I blew up their bike but mine r 155 m,45p,1173 needle.i wouldn't run a 142/5 m in mine with my steup on my bike u may have info i'm not aware of to make it work however?

 

[Brian]

Nope. Just found out I was reading the 220 recommendations off of JustKDX. How does you're bike run with that setup? Is it stock? Mine is bone stock except for the removal of the airbox lid.

Just to clarify things, I'm running:

148 main
42 pilot
stock needle in 2nd from top

 

[acutemp]

Stan,
It's good to see that you are taking the jump and working on optimizing your jetting. The 148 main is probably to lean for your 200. If you have a 152-155 handy I would put it in and do a plug check to see where you are at. I really doubt that you have done any harm to your bike but I would take the safe route and go with a bigger main jet.--Dan

 

[gooby]

stan i have some things done,boysen power reeds ,fmf torque/pc2,no lid.the plug is perfect color ,it never fouls the plug runs great no matter how i'm ridin .putting when the boys r along or slow woods,or letten er stretch out in the upper gears. one kick starter too,i can't complain about a thing ,knock wood

 

[Brian]

Would it help to run the premix at 32:1 instead of 50:1 to prevent seizure if anything should happen? The only thing that I don't get is why it runs so much better now than stock? I thought pinging and knocking were a sign of being too lean? I'm all confused, but will pick up some jets tomorrow and try that out.

 

[gooby]

it's better cause u leaned er out , a lean running motor creates more power to a point of going too far. don't mess with the premix .i've heard many here run 50:1 u should b able to tune to that.premix is not a jetting tool unless u fully understand it's effects on the engine. this is from gorrs paper :Fuel and Oil Mixture Ratios
When we talk about the "fuel" in the air-fuel mixture for a two-stroke engine, we are really talking about a mixture of fuel and oil. If you richen the pre-mix ratio (20:1 as opposed to 30:1) there is more oil and less fuel in the same volume of liquid, which effectively leans the air-fuel ratio. And this fact gives the clever tuner one more tool to use when the correct jet is not available or when none of the standard jets are exactly right. You can richen the jetting by slightly reducing the pre-mix ratio (less oil). You can lean the jetting by increasing the pre-mix ratio (more oil). The best part is that changes in the pre-mix ratio affect the jetting over the entire throttle-opening range, but the changes in ratio must be small to prevent excess wear from lack of lubricating oil or fouled plugs from too much oil.

Pre-mix oils are formulated for a fairly narrow range of pre-mix ratios. You should examine the oil bottle for the oil manufacturer's suggestion on the pre-mix ratio. All production two-stroke dirt bikes have a sticker on the rear fender suggesting that you set the pre-mix ratio to 20:1 That sticker is put there for legal purposes. Always refer to the oil manufacturer's suggestion on pre-mix ratios. In general, small-displacement engines require a richer pre-mix ratio than do large-displacement engines because smaller engines have a higher peak rpm than larger engines. The higher the engine revs, the more lubrication it requires.

 

[canyncarvr]

!!32:1 is LEANER than 50:1!!! (what gooby said)

DON'T confuse premix ratio with air/fuel ratio. I think you've read this before......

'More' oil isn't going to make things 'safe' with a 'too lean' AF ratio.

The 148 is too lean. Quite a bit too lean. Like...change it now!

If you're doing plug-chop checks with an '8' series plug, you're likely jetting to color of a too cold plug, too!

ps:
The kawi sticker on the rear fender sez '32:1' 20:1 is for chainsaws. It HAS been shown (a paper published by a chainsaw mfg actually) that a two stroke engine makes MORE power the MORE oil is in the premix...up until the plug fouls.