1. Dismiss Notice

KX300 Jetting

Discussion in 'Fuel' started by Scoob, Aug 29, 2013.

  1. Scoob

    Scoob PR Founding Father

    Location:
    Nashport, OH
    Racing Number:
    55k
    OK, still ain't quite right on the Eric Gorr KX special. I mean it is very good, just not perfect yet. Will try and call Gorr again today, but saw this forum, so I said, what the hey...

    First let me tell you what Gorr said the first time I call and the instructions when I got the cylinder back. Basically it said richen the air jet and lean out the pilot, needle, and main. Seemed extreme and the opposite of what I would have thought, but after he explained that the increased volume pulls more gas through the jets that before, it kinda made sense. After calling him one time he suggested putting the needle in the middle if 2nd from top (which is was in middle) and/or trying a colder plug (BR9EIX vs. BR8EIX).

    I've tried a few different things, but have it back to stock pilot, needle clip up one (2nd from top), and stock main. The air screw I've tried 1/2 turn out to 2 turns out. Stock is 1 1/2. Plug looks a little dark I'd guess. Not a new plug though. It runs awesome up top. It's around 1/8 to 1/4 throttle its not perfect and coming off the throttle I get that noise that makes me think lean, but with plug dark, I dunno. Maybe I'm just stupid. Definately a possibility... Of course, jetting is rocket science, so...
     
  2. hershey

    hershey PR Elite

    Location:
    Ozone Layer
    Racing Number:
    01
    You're screwed. Gorr will NEVER touch anything of mine again.

    Sounds like the problem I have on my YZ125 motor he built except it happens at the 3/4 throttle area. Same sounds and dark plug. I have tried every jet/needle combo there is. After 2 years+ and only 10 hrs on the bike it has started to break the tips off the plug, not melt them but break them off. Gorr just tells me Im doing something wrong and there is an air leak. Three times it has happened, the first I figured it was a fluke. It ruined the cylinder, the piston and bent the rod. $675 to repair. Put it together and made 8 laps at the Vet Fest before it did it again. Luckly no cylinder damage. Put it together again and got a full tank of gas before it went poof. Gorr still tells me its an air leak even though I have it jetted so rich the plug is gooey black. I checked for air leaks many times but havent found one yet.

    There is another member on here with the same bike as mine and having the same issue just not breaking plugs.
     
  3. Scoob

    Scoob PR Founding Father

    Location:
    Nashport, OH
    Racing Number:
    55k
    Thanks for the confidence.

    Hopefully when/if it goes poof I do not so much with it. That uphill triple has me thinking every time... It's close, just not quite there. I might think about terring it down after the Battle...hopefully by choice not by necessity.

    Laters.
     
  4. flyin polack

    flyin polack PR Addict

    Location:
    Wilmot, Ohio
    Racing Number:
    48
    My RM144 runs like a raped ape! It took a month...and the nerve to drop the pilot from a 42.5 to a 37.5. Some needle work (bought leaner needle) and 2 leaner main. Runnnnns awesome! Nearly 30 hours on it on 3rd piston and rings. Plug the shade of Hallie Berry...pleasant dark tan... 100% Cam 2 with Slamsoil @ 40:1.
     
  5. k01

    k01 PR Elite

    I got "that noise", same place on a stock YZ 250. Turned out to be just a dirty pilot jet. And it was just a thin film layer in the jet. Might want to try a size larger with the pilot to see what happens?
    On another note, I've been messing with my '96 360 Husky since it was new and found that the jetting is very temperature and humidity dependent. And that carb doesn't have pilot. Seems to be at the best compromise setting now but a 15 degree temperature change can make a difference, enough to make "that noise" at times.
     
  6. Scoob

    Scoob PR Founding Father

    Location:
    Nashport, OH
    Racing Number:
    55k
    I took some advice Gorr gave me the first time I called and tried a cooler plug, a BR9EIX vs. the stock BR8EIX. Did seem to run much better. I am not 100% on if it is simply because it was a new plug or being the colder one. It started quicker and was more responsive. "That noise" was not that often if at all after that. Come to think of it, I don't recall hearing it yesterday during practice or my 4 motos... ???
     
  7. mjshafer62

    mjshafer62 PR Addict

    Location:
    Westerville, OH
    Racing Number:
    62
  8. Scoob

    Scoob PR Founding Father

    Location:
    Nashport, OH
    Racing Number:
    55k
    Thanks Shafer. I'll take a look....
     
  9. Scoob

    Scoob PR Founding Father

    Location:
    Nashport, OH
    Racing Number:
    55k
    Well, in the end, Gorr expected me to be more knowlegeable about jetting than I was. Telling me to lean out everything was not what he should have told me...

    I actually kept the stock pilot, leaned out the needle one clip, and went from a 160 to 170 main. Thinking I might try a 168 main when I get one as well as may try the BR9EIX again along with a new BR8EIX plug. I'm closing in on the end of my season and won't be riding for awhile. I may leave it as is for now as it seemed to run pretty good yesterday at the 'Cliff....
     
  10. Scoob

    Scoob PR Founding Father

    Location:
    Nashport, OH
    Racing Number:
    55k
    OK, back to this...

    I'm close. At BC this past weekend when on the gas up top, it was running out of gas it seemed. 'Tis when I started shifting early to avoid this. Anyway, I have the pilot on size down, can't recall the clip, but thinking middle, and I'm a few sizes up on the main (160 is stock, thinking I have a 172 in there now). In talking to a buddy, he says it sounds a lot like one of the newer Yami smoker issues where it was fixed by putting in a richer needle... BTW, my plug is still a dark brown.

    In looking for a new needle, I haven't found much telling me richer or leaner. I looked on like Rocky Mountain MC ATV and they seem to have 1 stock needle in stock and the rest will ship in 5-7 days. $25 bones each. Looking at Keihin Carbs website it lists some info for the PWK carbsm but the part numbers are not the same as Kawi's. I have NFTG needle stock. The Kawi site lists them all as options, but I cannot tell which is richer/leaner. Sure the shop can tell me, but I'm not at the shop right now... Also was looking for a tuning diagram. Searched the web, but two links were no longer valid. 'Tis the issue when dealing with an almost 10 year old bike I suppose...

    Any help appreciated. Nothing expected. I'll figure it out one way or another. Bike was running good except for way on top...
     
  11. Scoob

    Scoob PR Founding Father

    Location:
    Nashport, OH
    Racing Number:
    55k
    Oh, and my carb is a Keihin PWK38S
     
  12. flyin polack

    flyin polack PR Addict

    Location:
    Wilmot, Ohio
    Racing Number:
    48
    I was having issues with my RM144 not wanting to idle but still lean in spots. Worked and worked at it...it ran great but wouldn't idle. Tried a new choke assembly and boy did that change things. The bottom of the choke plunger is rubber and fits against a fuel intake. The rubber on the old unit had a deep ridge in it being 10 years old and probably wasn't seating correctly. Now it is back to playing with the jetting to get it right again.

    Just food for thought...
     
  13. Scoob

    Scoob PR Founding Father

    Location:
    Nashport, OH
    Racing Number:
    55k
    Yeah, it's a science for sure. SO many things go into it. As of now I think I'm good. Well, better. Someone who knows what they are doing could get it perfect. I have a 1 size leaner pilot, richer needle clip by one clip, and a majorly richer main. Thinking it was a 162 and I have a 178 in there now. Left the 178 while at the dunes. Thinking I am going to try a 175 for normal riding and/or warmer weather.

    Thanks. I can use all the thoughts and help I can get. :)
     
  14. Scoob

    Scoob PR Founding Father

    Location:
    Nashport, OH
    Racing Number:
    55k
    UPDATE:

    Rebuilt the bike a few weeks ago. Decided to play around with the jetting a little more and so glad I did. Anyone who know anything about jetting, well, maybe a little more than that probably looked at what I was running and knew that wasn't right. Had been reading about the Kattom 300 kit and what they had done which let me to where I am now. Not perfect, but in a much better place for sure...

    Pilot = 48 (50 stock)
    Main = 162 (160 stock)
    Needle = Stock on 4 clip from top (either 2nd or 3rd stock)

    I'm thinking a richer needle will do the trick. I need to talk to someone about that as there are a few different options on a needle to make it "richer" from what I have read. You can shorten the length, change the diameter or taper. So... :)
     

Share This Page