Jetting!!! Again and again and again!

[Good]

Gonna test more today  but it's raining so might not be accurate due to humidity.

Currently in the bike,

50 pilot
160 main
stock needle in the second slot from the short, or fat, end

Going to mix Maxima Super M (because I have some left, but normally use Amsoil) at 40:1 in 91 octane.

Upon messing with the air screw and the idle screw, I can get the idle surges to go away, but then it doesn't want to idle when it finally calms down.  I ran out of fuel after that last vid.  Getting more today.

I'm also gonna adjust my float like Cam did due to losing fuel at a slight lean.

After riding an '02 CR250 all last Saturday, I'll say my low end torque and responsiveness is WAY more on the K5, but the CR pipe kills my bike.  Down low though and responsiveness, my K5 owns.  But, on the pipe, that stock 250 runs like a scalded cat.  That's what I'm looking for, but times 10!!! (and why I bought the mighty K5 in the first place.)

Thanks for all your help.  I think eventually I need to take apart my KIPS valve...

[KXcam22]

Good,
It is a goodpractise when jetting to keep all outside variables constant. The humidity I never worry about too much but plug heat range, fuel/oil brand and ratio and float level should be kept the same.  Can you get higher octane gas in your area without resorting to race gas?  92 or 94 would be better.  91 might be ok I have just never run it since I get 94 at the pump.  I am concerned that the 160 might be lean.  I would suggest doing a few plug chops to make sure it is ok before riding lots.  Your KX should eat an 02 CR250 in every power range.  I rode one of those back to back with my K5 as the owner was boasting about how much low end power it made.  Not much by K5 standards. What pipe do you have on your K5? Cam.

[Hillclimb#42]

Good, your original plan of 165, 55 was pretty solid, like KxCam is saying. Dealerships are bad about changing a gameplan due to out of stock parts. You probably should order that 165 main and 55, if they don't stock them. Too lean makes for a short engine life-span, and you are leaving power on the table. A plug chop is referring to holding the throttle at a position for a given period of time and then killing the motor. You check the plug color to see how the plug is colored. You are supposed to use a new plug each time and start with the main jet check. Start with stock or slightly richer than recommended by the jetting chart. (The jetting chart was right on the money for mine.) It was just a needle adjustment and mixture tweek to add a PC pipe and V-Force reeds.  FMF gives a jetting recommendation for specefic models and years for which pipe, on their website. Its hard to jet a bike with worn reeds, by the way. They should have a good seal around the edges, where no light is leaking through, if you hold them up and try to look through.
 Once you have your jets right, the needle is a big time adjustment for the mid thru top. It helps make your acceleration steady, when set right. Mixture screw is the tweek for condition and controls from idle to mids. Start with stock setting there too, and tweek for good throttle response. On my bike the idle adjustment seemed to cause alot of the over rev. Once I got the jetting and mixture right, the idle screw barely engages the slide. It idles fine, when cold, in neutral. Sometimes when warm, in gear, it wants to die because of the added drag, but still idles in neutral, warm or not. I run a 168 main and a 58 pilot, at a lower elevation, but I'm guessin' yours is way past compensating for the altitude. Starting a little rich( plug is dark) is perfect, no danger. Go one step leaner check again, till its brown/tan. Starting off on the lean side(green/white) is the risky way, expensive way.

[martinfan30]

Good, your original plan of 165, 55 was pretty solid, like KxCam is saying. Dealerships are bad about changing a gameplan due to out of stock parts. You probably should order that 165 main and 55, if they don't stock them. Too lean makes for a short engine life-span, and you are leaving power on the table. A plug chop is referring to holding the throttle at a position for a given period of time and then killing the motor. You check the plug color to see how the plug is colored. You are supposed to use a new plug each time and start with the main jet check. Start with stock or slightly richer than recommended by the jetting chart. (The jetting chart was right on the money for mine.) It was just a needle adjustment and mixture tweek to add a PC pipe and V-Force reeds.  FMF gives a jetting recommendation for specefic models and years for which pipe, on their website. Its hard to jet a bike with worn reeds, by the way. They should have a good seal around the edges, where no light is leaking through, if you hold them up and try to look through.
 Once you have your jets right, the needle is a big time adjustment for the mid thru top. It helps make your acceleration steady, when set right. Mixture screw is the tweek for condition and controls from idle to mids. Start with stock setting there too, and tweek for good throttle response. On my bike the idle adjustment seemed to cause alot of the over rev. Once I got the jetting and mixture right, the idle screw barely engages the slide. It idles fine, when cold, in neutral. Sometimes when warm, in gear, it wants to die because of the added drag, but still idles in neutral, warm or not. I run a 168 main and a 58 pilot, at a lower elevation, but I'm guessin' yours is way past compensating for the altitude. Starting a little rich( plug is dark) is perfect, no danger. Go one step leaner check again, till its brown/tan. Starting off on the lean side(green/white) is the risky way, expensive way.

Can I ask what your final needle set up is?

[Hillclimb#42]

Mine is as Pro Circuit recommends, 1 step leaner than stock, for the needle setting. I had to fatten my mixture when i added the V-force, and may still be a little lean through the mid, but have not had much seat time on the 500 to tell. I liked the jetting chart, when I was stock, the Pipe manufacturer's suggestion once I got the PcII, and the V-force cleaned up the rest. Plug looked good on the last ride, but it was not a normal summer day. I am confident I am very close.

[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.

[KXcam22]

Good,
  The 55 or 58 is more reasonable for your altitude and 40:1, and it agrees with the jetting chart.  Your 50 sounds waaay lean. Cam.

[Hick]

I have rode my 2003 k5 in several places, different temp/humidities and elevations and haven't touched my carb since installing vforce 2, jfab reed spacer and a Dial a jet on my carb.  I am happy with the performance of the dial a jet so far bike running clean and crisp.  Anyone else out there try one of these yet?

[atrain40]

I just checked out my jetting today since ive only had it awhile. its a 1991 kx500 with full PC exhaust and it is completely stock 168 main/60 pilot jet. i checked the plug first and it was really wet and i could tell it was running really rich. i am in california and ride mostly desert i am gonna try a 165/58 or some smaller ones as well i have to see what the dealer has. and also it does sound like its too rich, also alot of black splooge always comes out of the haeader and silencer big time. heard that is because it is running too rich and my mixing is at 32:1 but am thinking of switching to 40:1.

[PowerFiend]

  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.

The 02-07 CR250's have been consistent dyno performers, along with the KTM case reed motors, but the CR's have notoriously weak low-ends. I know, I have an 02 (eventual CR500AF donor) and an 07. They also don't have huge over-rev, but they hit like gangbusters in the mid-range.

Honda did not fully develop these motors, as proof of the success of the KTM case reed and some poor design items in the CR motor. (Large case volume, large squish clearance, etc.)

[slow600]

well here is my jetting question. bike is getting harder and harder to start, espectially when motor is hot or warm. been getting worse since the temp has been going up. bike currently is at 172 main, 55 pilot, needle second from the top and air screw 2 turns out. seems like is too rich, plug looks a little fat and bike will start in one kick if new plug put in. my first instinct is to put in a smaller pilot but im always leary of going to lean. is my thought process currect or not? btw im at 1300' elevation. thanks