Jetting

[littlewing78]

I recently got a new top end and now my bike is running too rich. It is a 99 KX 500. It runs great but smokes a ton and a new spark plug will be black after one ride.  I checked out the jetting chart to see what is recommended.  So I took my carb off to see what I was running.  Maybe I am reading the jets wrong but the number seem to be way off compared to the chart.

The needle is right with an N82M.  It was on the 3rd clip so I moved it to the 4th.  Didn't seem to make a difference.
The Main jet has what looks like a check mark and then a 48.  Maybe the check mark is supposed to be a 1.
The Pilot jet is 85.
I have the air screw at 1-1/2 out.

I am not experienced with this at all but those numbers don't even seem to be in the ball park.  Everything is stock except for the new wiseco piston.
I run 91 octane pump gas at 32:1.  And I am at 5000 ft.  Any suggestions?  Thanks

[alward25]

Wow a 148 is way too lean and an 86 pilot is way toooo rich.  165- 172 main and a 52-58 pilot is pretty standard  If the rest of the engine is in good shape that should put you in the right neck of the woods.  The bikes that run at the salt flats in Utah usually run a 165 main and a 55 pilot  of at least in that neck of the woods. I know there some higher altitude guys around that could chime in. 

[Polar-Bus]

I recently got a new top end and now my bike is running too rich. It is a 99 KX 500. It runs great but smokes a ton and a new spark plug will be black after one ride.  I checked out the jetting chart to see what is recommended.  So I took my carb off to see what I was running.  Maybe I am reading the jets wrong but the number seem to be way off compared to the chart.

The needle is right with an N82M.  It was on the 3rd clip so I moved it to the 4th.  Didn't seem to make a difference.
The Main jet has what looks like a check mark and then a 48.  Maybe the check mark is supposed to be a 1.
The Pilot jet is 85.
I have the air screw at 1-1/2 out.

I am not experienced with this at all but those numbers don't even seem to be in the ball park.  Everything is stock except for the new wiseco piston.
I run 91 octane pump gas at 32:1.  And I am at 5000 ft.  Any suggestions?  Thanks

Are you kidding me a #85 pilot ?!!!! How the hell does that 500 even start let alone run without immediately wet fouling the sparkplug  ? That is SO pig rich, no wonder the bike smokes so much. I normally don't like to give out my jetting but in this peticular case I will. Keep in mind my jetting should get you in the ballpark, I am NO jetting guru, but my 500 runs perfect with this jetting. You might need to fine tune a tad richer or leaner to compensate for air temps. This should be a decent baseline for temps around 65F.  Try this :

#165 main
#55 pilot
stock needle in clip pos #3
air screw 2 turns out from closed

If after this your 500 still runs bad you need to do a compression test. Make sure your compression is up around 160 psi . DON'T  "assume" because you have a new top end that the compression is good.

[Motorrad]

Before you go changing things...

I always tell people...   What was the last thing you touched?


In otherwords..

Did it run fine before the rebuild? or is this a new thing its doing only since the rebuild?

[littlewing78]

Thanks for sharing your top secret formula with me Polar.  The bike isn't running bad at all.  It runs just as good as it did before the new top end.  It's just noticeably richer now.  I have had the bike since last august and have yet to foul a spark plug either.  When I first got the bike the air screw was set at 4-1/2 turns out. Thats really the only change I made other than the top end.  Thank for the advise.  I'll get those jets and see how it does.

[Polar-Bus]

Thanks for sharing your top secret formula with me Polar.  The bike isn't running bad at all.  It runs just as good as it did before the new top end.  It's just noticeably richer now.  I have had the bike since last august and have yet to foul a spark plug either.  When I first got the bike the air screw was set at 4-1/2 turns out. Thats really the only change I made other than the top end.  Thank for the advise.  I'll get those jets and see how it does.

There is nothing "top secret" about my jetting. The reason I don't like to disclose my jetting is not to "hide" my specs, but because there are SO many jetting variables to take under consideration that no 2 KX500's will run the same. There can be 2 identical KX500's however one user is at 3000' altitude, and the other is at sea level and temps of 50F which will undoubtably require two very different jet specs. Performance mod also play a large role in jetting as does even the smallest detail such as what you run for a premix ratio.  I also recommend you lean out your premix ratio to about 42:1. Unless you are running your KX500 hard out in the desert, there is no need for a 32:1 ratio.  Try my jetting and premix, and if your engine is in healthy condition, your KX500 should stand your hair on end from the brutal power...

[littlewing78]

your KX500 should stand your hair on end from the brutal power...

That's what I am hoping for and afraid of at the same time.  This is my first bike so the fact that I am still alive should tell you that my KX is not running at its full potential.  I'll get those Jets on the way and in the mean time I have some rear wheel bearing to replace.  Thanks for your help.

[crazyolbastard]

I`m close to your elevation and run a 165 main and 55 pilot,  N82 M third posiion.

A turn and a half.

32 to 1

This is a great support group.
Try a search,   a ton a jetting help there

[littlewing78]

Thanks Crazy.  Seems that every agrees on the same jetting here so I will go with that.  I did research it on here but mine were so far off that I had to ask. 

[littlewing78]

Well hello Mr. KX, nice of you to wake up!
Got the new jets put in today.  I think it made a difference.  Seemed a bit more responsive.  I only got to ride for a little bit though.  I will put in a new spark plug next time to see how its doing.  I did check compression after the ride.  Kind of low at 135 psi.  I am using the thickest head gasket available.  Should I start there to raise my compression?

[Polar-Bus]

Well hello Mr. KX, nice of you to wake up!
Got the new jets put in today.  I think it made a difference.  Seemed a bit more responsive.  I only got to ride for a little bit though.  I will put in a new spark plug next time to see how its doing.  I did check compression after the ride.  Kind of low at 135 psi.  I am using the thickest head gasket available.  Should I start there to raise my compression?

What was the reasoning behind installing the optional  "thicker"  head gasket ?  135 psi is too low.  

The generall reason Kawi offers 3 different thickness OEM head gaskets is to allow some flexability for achieving adequate compression ratios when engine tuners modify the cylinders'  intake and exhaust port heights.  This along with using multiple base gaskets can allow the rider to shift the power curve slightly up or down the RPM range. If you have a stock KX500 there is no reason to run the thick head gasket, all's you are doing is loosing compression and power.  Here's a video of me and my "new to a KX500" buddy riding my bike :

 http://www.livevideo.com/video/RideYourRide/2BE8E85EDE0645D7BB7159012F90BDBA/8-9-07-riding-the-man-bike.aspx

Listen to the tone of the engine it's revving crisp and clean (and my jetting is a tad rich, but I don't jet max lean for max hp, I jet for clean running and good engine protection). If your engine sounds deep and burbly your jetting is still rich (or a poor top end).  Keep in mind my KX500 was struggling for traction on the dusty gravel road in the vid. When a KX 500 is putting down ideal traction, these KX500's are absolutely brutal as far as power ! Hope you get your bike sorted out .

[littlewing78]

I bought a re plated cylinder from from a guy and he sent me the Head gasket too so I used it.  I do have a thinner gasket I can throw on there.  I was also worried about the piston to head clearance.  I need to get me some solder to check the squish.  Keep the suggestions coming and thanks for all the help.

[Polar-Bus]

Don't know if you guys watched the complete video, but near the end I do a few sweet WFO blasts. The scary issue was at the end of that road in front of the brick building was a huge fence across the road.... I tried to catch 5th WFO, but just didn't have enough straightaway befor killing myself into that fence,