KX Riders
Maintenance & Technical => KX500 Original => Topic started by: tomasaki on May 07, 2003, 04:40:44 PM
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I have a hard time keeping my idle on my '01KX500. It always slowly fades down, especially going down a long slow hill with the clutch in. I always have to keep revving it. Anyone else have this problem??? I mainly woods ride. Alot of slow stuff. I have the main jet at 165, clip at top #1 notch, 52 pj. The idle screw is only out 1 turn from seated. If I turn it up more it runs away sometimes. The performance is great!!! My BR8EG plug is always black though. I can't go any leaner. If I lean the pj, it surges, If I lean the main in dies at full throttle. It's very crisp and responsive. It just won't idle for long. Any suggestions??? I'm thinking of trying a hotter B7ES plug since I mainly ride at low RPM's where I can control the power. Thanks for all suggestions.
Tom L.
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Yo Tom, whats your altitude? And having the clip in the first notch is bad. What was factory setting?
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yzmike: I don't know my altitude here in Western PA, but I think it is fairly high. There are alot of mountains around. The factory main was 168, pj60, clip in the center. With the factory jetting, I could not let off the gas for a second without it fouling horribly like I had the choke on. If I don't keep the clip at the top, it loads up from bogging around too much in the woods. It's done this since it was new from the factory. It's totally stock other than the FWW.
Tom L.
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I don't know my altitude here in Western PA...
I'm 40 miles west of Da 'Burgh and I'm around 1000'. I have a 170 main and a 52 slow jet and don't have any fouling problems. I even got it to idle with a 60 slow jet, but it would eventually die. I have no idea what needle is in it though. I assume it's marked on it. I 'spose I should look.
Ya might want to take the carb off and clean all the passages, check the needle & seat for wear, and reset the float level.
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Lets look at some contributing factors, what type of 2 stroke oil do you use? what ratio? Also sounds like to live near Pittsburg, or Kittanning. This could call for jet change also. I know you will find the correct combination. YZ Mike
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YZMIKE: I use Mobil 1 synthetic 2-stroke oil at 32:1. I live about an hour east of Pittsburgh at the base of the Laurel highlands.
GWCRIM: Does your spark plug stay clean?
Tom L.
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Dump the EG plug and switch to a BR8EVX before you monkey with anything else. I have never gotten a bike to run right with the EG, so I always switch out the plug first thing on new bikes.
Look at it this way, for less than $10, it's worth a try....
Good luck. Problems with our toys don't make for happy boys...
Rick
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Thanks Rick! I'll give it a try. What is different about the BR8EVX plug?
Tom L.
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I have had the very same problem with my 89. I have rejetted it until I actually had it to idle - but was way to lean, so back on square one.
This weekend I changed the piston and mounted a home made spacer kit (17 mm). The bike now idles.
This could however have been caused by the fact that there is now only one top head gasket instead of two. (The previous owner probably had some leaking problems...) The compression is higher and the bike is more responsive - loads of torque :) . I am going to take away the spacer once I have received the proper one from Moose. I will test and see if it was the higher compression or the spacer who did the trick. Moose deliveries to UK sucks so expect 6 weeks minimum...
/John
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You can tell that these guys have experience in solving complicated problems, so truthfully. the only thing I can add is DEFINITLY use a premix oil that can run at 50 to 1, this alone should clean up the plug! I will buy moose spacer also. Keep writing about everthing you try.
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Thanks Guys!!! It'll be an easy thing to try to run the Mobil 1 MX2T at 40:1 instead of 32:1. I guess 32:1 is only necessary if you're running hard. I just fart around in the woods at low rpm's. I'll bet if I run 40:1 with a BR7ES plug, it should stay fairly clean. I'll let you all know.
Tom L.
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Tomasaki, I've run 40:1 on a BR7ES for 18 months. The bike still fires up on the first or second kick. I use Maxima Super M
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Thanks KX500!!! I'll be trying this 40:1, BR7ES combo this weekend. I'll let you all know how it works out!!
Tom L.
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I had a chance to ride this weekend with the new 52 slow jet. I run MX2T @ 40:1, 1.5 turns on the idle mix and a #8 plug. When I got home I let the bike sit and idle and idle it did. No sign of dying out at all.
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I tried the 40:1 mix with b7es plug and didn't see any difference. The plug was still black at the end of the day. Performance was good as usual. However, it still won't idle for long no matter what pilot I put in. I've tried 48, 52, 55, 58, 60, &62 pilots. The only difference I get is runaway revving with less than a 58. I'll stick with the 58 for now. I cut some of the spring off of the idle screw so I can turn it in further. This seemed to give me some more idle. I'll have to see next ride. The problem with having the idle screw in so far is the rpm's don't want to come down right away when I let off the gas.
I took out the reed valve and cleaned it. It was a little gunked up, but that didn't fix it either. Would a lighter reed valve help??? Like low tension carbon fiber maybe??? I was just thinking maybe the stock reed valve is a bit heavy and doesn't respond well at an idle. Does this make sense??? :?:
Tom L.
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Tomasaki, have the bottom end pressure tested. You're showing the classic signs of a leaking seal on the oil side of the engine. Also perform a compression test to ensure your compression is between 110PSI and 170PSI.
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Thanks Paul, But how do you check bottom end pressure??? I've never done a compression test either but it seems like you would just hook a gage to the spark plug hole and crank it.
Tom L.
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Thats correct, a compression tester plugs into the sparkpulg hole and you kick the engine over until the pressure no longer rises on the gauge. This will tell you if you're in the service limits of: 110psi - 170psi.
Everytime I do a topend on my bike I pull the piston and put the jug back on the engine. I have a pressure gauge that threads into the sparkplug hole and a rubber stopper (gotta love Home Depot :lol: ) that seals the exhaust port. I have a flat plate with a valvestem (like your car tire) in it that i use a bicycle pump with to pressurize the cylinder. Flat plate bolts to intake side of the cylinder. A couple pounds (ehh, more like 7 or so) is all it takes and then you just watch the gauge for bleed off. If everything is good then there shouldn't be any pressure bleed-off.
Good luck and we're here if you have more questions.
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Thanks again Paul!!! That all sounds easy enough! I'll call around and see if I can find a compression tester. The bottom end test will have to wait until I'm due for top end.
How does this all affect the idle? Other than the idle dying off, and the spark plug always being black, the bike performs outstanding.
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hello ,
my 01 500 do'es the very same thing. as soon as i let go of the throttle it will pulse and rev on by itself... thanks, jdv
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my 01 500 will pulse and surge by itself evrytime i let the throttle go after a straight and level run,
with the gas shut and rolling, the revs will bounce up 3 or 4 little peaks and the bike will surge forward in sequence. any help would be great thanks.!! jdv
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Tom, After trying everything, plugs, all jets, oils, ratios, etc. I finally made my own Idle Screw just a few threads longer than stock and shaped the end on my bench grinder-like the stock screw. Idles nice, I can adjust it a lot better now. It doesn't surge and runs clean due to all of the jetting. I run Maxima Super M at 40:1 with a BR7EVX and 92 Octane Pump.
Rick K.
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John,
Good for you with the rebuilt and you don?t need 2 gasket, I promise!
(The moose is something around 10mm)
//doordie
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Joseph,
Unfortunately, that surging seems to be quite normal when the jettting is good. Mine does it just like you describe, maybe worse. Gowen did a lot of testing and the surging only seems to go away when you are too rich. I doesn't bother me when I ride so I have got used to it. Probably not the answer you were looking for. Cam.
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yeah,
i often relying on the engine braking and during this is when i feel it . thanks, jdv
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Just a quick question I get some small surges under these conditions (hi speed to chopped throttle) The bike only accelerates for one "pop" and not very often. The odd thing is my jetting is a Little rich. I was thinking a worn slide? Its not a big deal I was just looking for opinions.
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The surging on the 500 is normal... you can search for posts on this subject as there are a ton.
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Yes I have been reading......but for some it seems to go away when jetted rich. I am jetted rich and it is still doing it, so I was wondering if my thoughts on a worn slide hold water. :)
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Maybe carboned up power valves(sticking)mine is a little rich but pusled and surge a little bit but after I cleaned and re-lubed the valves problem solved.