Maintenance & Technical > KX500 Original
Jetting!!! Again and again and again!
kawdude:
So is the knocking not piston slap? I'm concerned that it will lock up if I run it that way. Also, are you able to change the jets and the clip with removing seat, gas tank and carb. That's what really pisses me off. The weather hear was beautiful on Sunday also which probably had something to do with it. It amazed me that 1 notch took the snap away since all the diagrams I've seen say the needle jet doesn't do much until mid...that's bs. I'll screw with it somemore. At least, this time I got changes in performance. It seems to me that my bike is better at 52. I'd be afraid to try anything smaller, however, the main jet needs to be dropped to 165 at least because when I got on it it fell flat. I suppose the exhaust valves could be stuck but d**n I've only put around 15 - 20 hours on it since the rebuild. Thanks for your help!
One other thing...
The bike started on the 3rd kick!!! Hell, I was still priming it. No racing rev at the start either. Next time I do this i plan to change/clean the airfilter. I've been using a filterskin with oil applied to that also. It's probably plugged.
kawdude:
--- Quote from: KXcam22 ---Your jetting saga is interesting reading.
--- End quote ---
Thanks for reading it! This is Gowen's work in progress so take anything I say with a grain of salt on the jetting topic. I really don't know what I'm doing here :shock: !!!
KXcam22:
Gowen,
Your bike jetting sounds like a tough nut to crack. You seem to be always headed in the right direction but not quite getting there. Frustrating I bet! I would suggest that you may have to dial in the main (plug chop runs up a hill) first and lean the pilot (get a nice idle) then leave them alone and try some different needles until the transition is nice. Possibly a leaner needle might be the ticket. Then you could run the needle higher than you normally do to richen the 1/4-1/2 throttle but it would be leaner (ie thicker straight section on the needle) at 3/4. Also some dumb things would be to check the tank cap vent & petcock fuel flow. I have had a partial plugged vent that would partially airlock the tank after a few hours and leanout the carb by reducing the fuel flow and lowering the float level. Have you done the tape thing on the grip and marked the throttle incremants. It helps to tell which jet a weird symptom is comming from (just tell your friends the 1/4 mark is all your allowed to use when racing against hondas). At 42 on the pilot you may be able to borrow 40 & 38 from a 300EXC owner since those are the stock sizes that they have to take out to actualy make then run (same carb). It's easy to be an armchair quarterback so feel free to ignore me if I sound off the mark. Best of luck Cam.
KXcam22:
Your are probably way past this but, I thought I'd mention it. When jetting it is good to set & not touch the float level. An easy method I use to set mine is to (with the carb on the bench) put a piece of spare fuel line on and blow (used fuel line tastes bad) into it while tipping the carb back with the float pivot pointed up. When the air flow stops, that is your float level. On the KX the rib in the center of the float should be parallel (or almost) to the carb body but not past. You will find this matches the stock specs. Cam.
gowen:
Kawdude, You do not have to remove the tank and seat to change the needle and carb, I just pull the carb out a bit and remove the cap. This can be done by pulling the air box boot back when the clip has been loosened on the carb then popping the carb right out. Pretty simple and saves time. From what I've learned, there is NO substitute for correct jetting. As in, you will get the MOST power out of correct jetting, so if you find more power in the 2nd notch, I would keep it there and keep on working around it.
KXcam, I have tried the float height, but I will try it again, d**n I wish I knew what type of needle I have, then I would go a slot leaner. I know this for sure, when I'm on the 1st notch I'm DEAD lean. No wheelspin and the throttle acts like it is running out of gas, racing the engine.
Ah yes, the notch in the grips, I sure did it. :-) Great idea, which has helped me ALOT in the diagnose of lean and rich mixtures. The problem currently is, I'm juggling the low and mid range, gaining one and losing the other. I did a plug chop on a 162 and it came out dark grey around the BASE of the insulator. Assuming it is rich, I just started running 50:1 using MC1. So, we will see how this works out in a plug chop. The only place I can do a chop and really keep the throttle pinned is either at my Grandparents in Virgina which is like 4 hours away or the place I mentioned above, but is costly just to jet and takes an all day trip, which time is very scarse at my job. :-(
I have to take my KX to the machine shop for a new exhaust mount as it broke not one, not two, but all three mounts. And they were ALL together and fine last ride. :-( So, that will consume my free time. I'm having trouble locating a 158 main jet. Nobody around here has them. I've never thought about a KTM dealer, sounds like a plan for the pilots, as people here are like asking if I am running a moped or something like that.
My main feels pretty dialed in, but I understand the chop test. That is something I will take care of next. I will pick up the 40 & 38 next.
Help me out here for a second, I'm needing to know what needle to order for the next step leaner, it sounds like a plan but will need your help as I have NO idea how to read a needle, even after reading the justkdx report, it just confused me. ;-)
My needle reads: R1366N what would be the next step leaner?
Thanks Cam! I appreciate it. Same to you Kawdude, maybe all this info will get both our bikes screaming.
Btw, it is a spark knock from either the bike running too hot or the fuel not buring correctly (too rich usally), sometimes the timing off, in this case it sounds like a fuel issue (directly related to jetting) Anyway your engine would only be at stake cause it is a lean mixture.
Thanks for the help guys.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version