Only problem with my KX....

[GDubb]

The only problem I had with my new KX5 was this.... When I pull in the clutch, or click it into neutral, or even sometimes when the rear wheel leaves the ground, the RPMs race.  I either have to use the clutch as an engine brake when I'm sitting still or use the rear brake to slow it down when I'm slowing but still in gear and moving. I read in other posts that this can be caused by air leaks,  but before I checked into all that, I was wondering if my floats could have something to do with that because as I was having a friend that went riding with me listen to it to try and troubleshoot the problem, he noticed that I was steadily leaking fuel from my vent hose. So could this be the problem? He seems to think that it may be the cause. I plan to pull the carb tomorrow after work and see what I can find but wanted to see what you all had to say first. I'm hoping that this could be the problem as it sure seems that this would be much easier to remedy than tracing down an air leak.  Also... does anyone know a standard measurement for the float levels? I know its 16mm or something but have no way to measure mm.

[hughes]

I have nevered noticed fuel leaking from my vent lines. But you are on the right track with the floats. You may have one hunging up or the needle/seat is worn. Extra fuel with no load on the engine could make it rev. up. Check out the carb.

[KXcam22]

Gdubb,
  Search in the jetting section. I posted easy instructions for setting the float level without measuring.  Also, check the carb mounts for leakage. My carb clamps were not round so I replaced them with a narrow hose clamp from an autoparts store.  A narrow hose clamp from a 2002 KTM EXC will do for the rear.  A too lean pilot jet will also cause that, more noticable when the engine is hot. Good luck. Cam.

[reknelb]

Fuel coming out of the overflow hose is usually from a worn needle valve. If your bike is brand new and leaking, it could be that the float height is way too low. The float bowl could be filling up and never actuating the needle valve if the height is wrong. If the height was to high, then the floats would actuate the needle valve too early and starve the engine of fuel on wide open bursts, but there usually isn't fuel coming out of the overflow in that situation. float height is supposed to be 15-17mm

[GDubb]

Cam,
  I searched forever and finally found your float level post, i'll tear into it after work today. As far as the pilot jet... I hate to admit this... but I dont even know where that is! The only jet I've ever had to mess with on any bike is the main. Ive never even had to mess with my needle other than to make sure it was in the position the bike shop told me that it should be, and coincidently, it has always been in the right spot.  The only thing I know is that the bike had a 165 main when I got it, I bought a jet 2 sizes richer for the dunes which I believe is sea level, and the needle is clipped on the second from the bottom. Anyways, I'll pull the carb and check the float level and the needle valve and start there. While I'm in there I'll see about locating the pilot and see what size it is and reference it with the jetting chart. Thanks for the help!

[KXcam22]

Gdubb,
   With a 165 main your bike was likley jetted for a much higher elevation.  The Sudco website should have some diagams to help you locate the pilot jet. Probably a 58 will be about right. Cam.

[GDubb]

Ok, I pulled my carb today, I checked the floats using your method, and as far as I can tell they are, or are at least close to parallel when the airflow stops. The new main jet I purchased is a 170, the pilot jet is a 55, and the needle(N82M) is on the second from bottom.  I was riding on the oregon coast so that would be right at sea level when I was having the problems.  I checked the jetting chart and it looks like I could be lean with the pilot? and maybe the clip on the needle could be wrong too??? Looking at the chart I shouldve been at a 172, 60, and the needle on the third. Could this be the cause of my revving when not in gear?  I'm sure you guys are beyond SICK of jetting issues, but I appreciate your help!

Cam, I noticed in your post that you said that the pilot issue would be more noticeable when the engine was hot, and indeed, it started after the bike had a few mins to warm up. Hopefully this is the cause then?

[hughes]

GDubb,

Jetting has nothing to do with the fact that you had raw fuel leaking from the carb/float bowl vent lines. Jetting is metered fuel going into the engine. Make sure you get one problem fixed before you move on to something else. just my 2cents

[GDubb]

Honestly I could care less if I leaked fuel all day long as long as the bike runs descent and nobody's following me around with a match. I'm more worried about the bike revving by itself when not in gear. So if the fuel leaking from the vent lines has nothing to do with that then I will worry about that later. I checked the floats the best I could and they seem to be ok, So what else could be the cause of the fuel running all over the ground?  I hate working on these d**n things when I really dont know s**t about them. If I didnt have a wife and kid I would go to MMI and then I would be the one answering all of your questions instead of feeling like I'm a pain in the ass. I wish I was Ricky Carmicheal so all I had to do was ride the d**n thing and let somebody else worry about the wrenching. But anyways, I'm done throwing my fit... any suggestions?

[hughes]

those vent line are  atmospheric vent allowing air to enter or exit the carb bowl. If there is fuel leaking from one of those lines the carb is trying to flood out. Normally when a carb floods it enter the engine and causes it to run poorly. On dirt bike carbs when they flood most of the extra fuel is dumped out the vents and some will go into the engine. You could have a needle or seat problem. FLoat level could be good but if you have a worn needle it will not seal off when the fuel level rises and pushes the float up and pushes the needle into the seat. Basicly you have fuel running straight through from your tank and through the carb and on to the ground. The needle must seal when it is seated in the seat. Hope this sh*t makes some cents.

[Ramski]

Don't know about the fuel problem, but I did have my revs race up whenever in neutral or whenever I didn't have a load on the engine.  My problem turned out to be the throttle slide in the carb was not fully seating.  Easy fix.  Just the carb away from the air boot and unscrewed the throttle slide and re-seated it.

[KXcam22]

GDubb,
  Sometimes half the fun of having a bike is working on it; learning to fix it (sometimes the hard way) making parts and tweaking it to make it better. I would suggest trying the jetting guides recommendations exactly on your next ride.  I've found them to be very close.  I had the same thing idle thing happen to me my last ride. I normally use a 58 pilot but leaned out to a 55 just to try it for the summer.  Was great but on my last ride in October in the snow, the 55 pilot was too lean to handle the increased air density at the colder temps(more air per fuel=leaner), so when the bike got hot the idle would run away. In that case I was just a touch on the lean side and the idle run-a-way would only show up when the engine was really hot. Ramski has a good point about the slide. When you open your throttle (engine off) and let is snap closed you should always hear a good strong "click" as the slide bottoms. No click means the throttle is not going to close fully. Cam.

[mikesmith]

I just want to add that normally the float bowl is supposed to parallel the carb body,but I found setting mine higher than specs (19 or 20mm?Its been awhile) solved my blubbering in the rough,fuel going out the overflow lines when the bike was at the slightest angle and of course better gas milage!Could be your floats just stuck.

[GDubb]

Thanks for the input guys! Just one more question regarding the jetting: On the jetting chart it states that he is running a V-force reed cage, I could be wrong, but dont you have to rejet when using V-force? What I'm getting at is that since I'm not running a V-force do I need to be 1 step leaner than what the chart says because of the stock reeds? Also, I have nothing to measure mm with so what would you recommend that I purchase as a good tool for setting my floats?

[mikesmith]

3/4" is 19mm,use that and see how it works.The 500 is sensitive (at least Ive found to get the most out of it) to jetting.Temp,altitude,humidity effect jetting,so jetting is always changing some what.Take notes for referance as to what works at settings for the differnt seasons and riding areas (altitude) so itll be easier to jet in the future.Do one change at a time to keep track of how it effects the bike,the chart is just a starting point,not the Bible.Theres some good jetting post (how tos) here,so check them out and be patient.