Maintenance & Technical > KX500 Original
Jetting!!! Again and again and again!
gowen:
:worship: :worship: Cam!
Thanks!! That is the ticket I was needing. Knowing your bike is doing the same deal has let a load off my mind. I am goin out riding tomarrow and will give you a report of the needle swaps and everything else that occures. Will work on the dial a wheelie and see if bringing the CGK to a CGJ and so forth! Thanks again! Wow.. :drunk:
Now Kawdude can get his fixed up too.
Thanks again Cam!
--- Quote from: gowen ---
--- Quote from: KXcam22 ---Gabe,
Those are good test result (just not what we wanted). Did you try riding it with the CGJ? What slide # is in your carb? So much for my theory.....d**n now I'm really curious. It's dark here or I would go fire up my bike right now. For sure I'll try it early in the morning. Cam.
--- End quote ---
--- End quote ---
RexRob:
Hi Guys,
I have been viewing this project for a while, actually since getting my 2004 in sept. I bought it since they were (for stupid reasons) going to be discontinued. I had a 91 and loved it, missed the hooligan power rush! Bike was hard to get, called over 20 dealers and wound up getting it in MD, wish I could have got it closer...
Well my bike was running rich (I broke it in as recomended) all I got was black plugs even after it was broke in, though I think some of it was the plug. I haven't been riding it since the first week I got it and went to my dad's (5 hrs. away but 110 acres).
Today was the day I was going to do something about it, I yanked off the carb and checked the float with a caliper, it was fine. I had jets I ordered from pro flo (took 2 weeks to get them because of hurricaned in Fl.) I probably made too many changes at once however. My main problem was (besides the black plugs) was it would not idle for crap, maybe 3 sec's with the air at 2 1/2 and the idle screw in all the way. I dropped the pilot from a 58 to a 52, main from a 168 to a 165, and the clip up a notch (2nd from top). I also cut the gas, I was using camII 110 octane straight with 40:1 H1R. I used 1 gallon of that mix and a gallon of super unleaded mis 93 octane.
I started it up and took the choke off right away, it idled by itself, but fast. Turned the slide screw out 2 turns at least and it still idled like a dream! Took off after warming it up some and then rode easy a little bit to get it up to temp then cleared her out. What I can say is that it runs incredible, wheelie any gear and moving dirt like a grader. No hesitation, idle is still a little too fast, and guess what, since day one I have the same thing you all have, the dreaded surging to idle, must be the nature of the beast. Sure glad it has good brakes! Nailing it down the street on the back tire in 4th then chopping the throttle it does not slow down quickly by itself, it will do it in any gear and neutral. Hit the gas, and just like gowens audio, the same thing.
After letting it cool down I pulled the plug, and expecting to see black (the usual) I saw something way different. It was tan, not white, not black, and this was not a plug chop. It was dry, even the metal on the bottom was clean and dry, before there would be oil on it. I hope I am not too lean somewheres. It ran perfect, scary as a matter of fact, except for the surging thing which it always did. Perhaps the carb is too small for the bike? I mean 250's run 38's. this is only 2x as big, and 1 mm more. I have seen 125's with 39's on them! Somewhere down the road it would be nice to try the 41mm, price is not bad (low 200's) and I think it belongs on there anyways. The temp here today was 68 and dry, I am at around 1200 ft. If I keep the jetting the same I will not run it in colder weather, only warmer or I might try changing the main back to stock (168) if I can get a tool to get it out without removing the carb again. Overall a HUGE improvement!
Thanks Guys,
Rob
gowen:
Rob, that's awesome. Thanks for the input. I'm still in shock about the surging. But a good shock. :-)
Well, an update on the work: I went riding today, had an awesome time. Rode for 5 hours non-stop. I have to say... I love this bike. It ran soooooo nice. Idled! But, after about 3 hours of riding, I did start to notice that 1/4th throttle was pretty lean. When I'd put the throttle at 1/4th, it would absolutely hit the peak RPM and slide everywhere immediately. But, it was not a healthy REV. It felt very lean and uncontrolable. So, I hopped off and turned the air screw in a full turn. It did not help, but hurt the idle a little. It was ONLY at 1/4th throttle. I'm assuming the needle needed to be moved from the CGK to the CGJ. Then, after another hour, the 1/4th was still lean, the half and full throttle felt like it was not near as powerful. Dial-a-wheelie was not working out so great. I'd really have to full throttle it HARD to keep a wheel up. So, I'm thinking it was starting by the needle diameter. As I have the clip on the 4th. It's been a great day! I had so much fun. I felt like I was riding a 250 for a while, until the lean symptoms came out.
Anyway, only two problems of the day. First: As soon as I kicked it into gear, the clutch cable snapped right at the lever. Anyway, thanks to a lot of bolts and hardware I was able to rig something. Second: I busted a pipe mount again. I'm thinking I need to find a new welder as this is not working out. Keeps busting.
Anyway, thanks for everybodys help. I need to work on my jetting a little, but nothing major. It ran great, except that one spot that was a little scary due to over sensitive throttle at the 1/4th.
Would you guys think it is the needle diameter?
Thanks
RexRob:
Gabe,
As far as all my research goes it seems that the 500 is a bear to jet, even if you do it can change with the weather. I really don't remember having any problems with my '91, always ran good as far as I know. Too bad you don't have an a/f meter on it, that sounds like it would be invaluable to getting it perfect, you would be able to read the mixture at the pipe. By the way, what color were your plugs? They do tend to give you a lot of info.
Also, and possibly what could help with the surging thing is the slide. Maybe try getting the richer slide, according to Gorr's website here is the breakdown of what effects what:
Closed to 1/8 throttle air screw and pilot/slow jet
1/8 to 1/4 throttle: air-screw, pilot/slow jet, and throttle slide
1/4 to 1/2 throttle: throttle slide and jet needle
1/2 to full open: jet needle, spray-bar/needle jet, main jet, and air jet
Seems like the slide plays a major role in a variety of throttle openings, dunno, but it's a thought. Maybe sudco has them for $10, might be worth a try....
Looking back through the years, I had almost 20 bikes, and I can still remember my first mx'er 1982 rm 125. That ran perfect from day 1, In the winter in the snow and on 90+ degree days nothing ever phazed it.
Lastly, did you ever try boyesen reeds in it? Or a reed spacer? I think somewhere is the answer to getting the surging solved.
Reguards,
Rob
KXcam22:
Gabe,
Glad you had a good day! Did you try the richer needle or just ride? Was one mine yesterday, definitely surges worse than yours but I never notice when I'm riding. Sweet bike, I'll put up with the surges! My boysens and reedspacer don't alter the surging at all (make power smoother only). I don't think the KX is a bear to jet, but it doesn't necessarily respond as crisp as other bikes. At altitude (6000'+) mine is the best running bike of the group I ride with. The KTM's barely run. It's fun being able to outstart the e-start bikes. Cam.
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