Maintenance & Technical > KX500 Original

Jetting!!! Again and again and again!

<< < (68/120) > >>

Good:
Are you still running the PWK?

Hillclimb#42:
Stock carb, ...stock bore, stroke,head, porting, everything is stock except Pipe, silencer, reeds, bolt-mod and timing. IMO, only, and correct me if I'm wrong, anyone, I have been wrong before, plenty, so don't take my opinion only, but if you are putting out more power than stock with mods like porting and head work, you would be richer than stock jetting. I think, to put out more power with a mod, it takes more fuel to run that mod. Otherwise, a stock motor should be close to stock jetting, with the main maybe two sizes one way or another, max. Clip position, would be stock or adjusted up or down one to tweek power delivery.
 My theory is sketchy ,as there is always exceptions, PC actually recommends a clip adjustment to one leaner than stock. That confuses me. A worn cylinder and rings will often require richer jetting. I don't quite understand that. Its important to do one thing at a time, keep notes on settings, results and temperatures. Keep in mind a drastic temperature change (like 30 degrees) cooler will lean out the jetting and, if it warms up 30, it will start causing a rich condition. Any attemt to "fix" jetting that has no or poor results, go back to original setting before trying something else. Then make a note. Over time those notes will speed up the process for you.
  Worn reeds, worn cylinders, smashed pipes, poor throttle cable operation, dirty air fiters, carboned up powervalves, old fuel, wrong spark plug, weak spark, worn carb, obstructed exhaust, or just about any uncontrolled variable will make it harder than without these hurdles.
 Also, it is important to remember, mixture screws and needle adjustments, make a big impact. shifter cart guys will tweak mixture in the middle of a lap. Small adjustments can make a big difference. It may seem like you get the motor running right, but then notice it revs to the top of that gear too fast. Don't be afraid to go taller gearing when looking for more power.  The 500 can pull taller gearing than a 250 comfortably. Check plug color when engine performance is in question.
  By the way, the 02-03 Cr 250's are very fast bikes (case/reed motor). I read an article that said they were putting out like 8hp over previous years. And many hillclimbs, my kx250 runs a better time than the 500. I continue to tweek on it, but the 500 will never be twice as fast like expected. There are still all the factors like traction, gearing, chasis and fear probably, that seperates them.

Good:
Tried to tune yesterday

3000' elevation
160 main
50 pilot
needle second clip
stock slide
don't see a difference from 1.25-2.5 turns on airscrew
idle screw almost all the way in (spring almost compressed)
40:1 ratio

idles for a few minutes (3-5) then will die or will idle high, depending on screw. Can't find a good balance in between.

Something I've noticed: Full throttle blows smoke, idle- 1/2 doesn't at all.

When I have it pinned, it blows pretty smelling smoke, and will after that every time I "bing" it shortly after the full throttle blast.  this can bee seen from my above videos.

But, when it idles for a while, it acts like it doesn't have any oil and won't smoke for nothing, even after I bing it.  This is after idling for a while. which makes me think the pilot is lean, but the main is good.  What do you think?

Get paid tonight, so I'll order the other pilots in the 50s tomorrow, but I'm close to idling now and I'm afraid to kill that progress.  It's better than killing the motor though!!! :|

bludyell:
Good - I ran 158/50 in Tahoe around 7500' in summer 90 heat - went fine. BUT that was after I put new reeds in - I'd played for weeks before that, couldn't get anything right. I didn't go back through your posts to see if you'd done the reeds yet?
Also, if you're blowing gunk from the pipe & no top-end I'm thinking you may have too much backpressure from the muffler- have you re-packed recently?
Hope this helps...

Hillclimb#42:
 Looks like the jetting chart is saying a 55 for the pilot. Have you set the floats and checked reeds? When you are switching back and forth on fuels and oils, I hope you are rinsing the tank out. Have you eyeballed the powervalve rod to see that it works right? The idle screwed in all the way opens the slide and overcomes the fuel or air shortage of the  pilot. That will add to the over rev., and be harder to notice mixture changes. Is it possible you have some blockage in the pilot circuit? Sounds like you are too close to have all this going on. Kam pointed out that clogged overflows can be tricky to diagnose.
  I can tell you for sure, that my 500 is running great, but does not rev-out like my 250. The k5 has all the bottom end I could want, it does wheelie on any traction, but is shorter power bursts. Its like the power pushes through the rpm range faster. Shorter overall rpm range than a 250 and get there twice as fast.  I am geared taller than my 250 and still shift sooner. :?
  I had a rich sounding and smoking condition with a Rad valve. It ran good, but not like it runs with the V-force. Its super crisp now, instead of the raspy sound that I had before. Also, I used to have a cold-natured condition that has went away. By cold-natured I mean, it used to be loaded up after a cold start. I used to have to get the power on the pipe to get the 500 to clean out. Don't know how V-force could have changed all of that, but there you go, thats all I changed.

Navigation

[0] Message Index

[#] Next page

[*] Previous page