Jetting!!! Again and again and again!

[dookie454]

I've got one for ya'll.   Got my stock 1994 KX500 12yrs ago, rode it hard since, lots of WOT, perfect jetting.  No fouled plugs ever.  Michigan Elevation ~1100ft.
I believe this was:
60 pilot, 1.5 turns out on the screw
168 main (since this single jet I found in my "KX500" bucket)
stock needle (for 1994 is N82R), center clip
#7 slide

Now ~3yr ago I changed the stock pipe to a FMF Gnarly, and followed whatever they recommended for main jet which was a 175 which I picked up at my local bike shop... HOWEVER...   ever since, the top end feels like it falls off, and to me it feels lean at WOT.   I took the carb apart today and found a "175RD" main... which I have come to learn is not an OEM jet... it's actually from here:  http://ebcbrakes.com/product/main-jets-for-carburettors/

So anybody have any idea if that jet is leaner or the same as a real Keihin 175?   If I put my stock 168 jet back in there... do you think that is OK with the FMF pipe?  FMF recommends 175 and a 58 pilot (I have 60 pilot).  

I'd say right now, it feels perfect to maybe just a bit lean from 1/4-3/4 throttle, then WOT, mid to higher RPM in my opinion seems weaker than it should... (lean).  

Thanks for any suggestions!!!  

[sandblaster]

Wow!
175 at that elevation?
Seems a tad on the rich side but I looked on their website and your correct.
Then again they might be on the conservative side intentionally.
I only use Keihin jets because others seem to be inconsistent on size.
It's time for you to do some wide open runs then kill the engine and pull the plug out and see exactly what it is doing.

[dookie454]

sandblaster, yep I think your right.  WOT it is.    To make matters worse, I just went to the same bike store (3 yrs later) and got 4 more jets... 178, 180, 182, 185 however they don't have the "RD" stamped on them like they used too yet they say they are not OEM Keihin so they are likely now on a scale of there own...   what a mess.   At least it starts first kick, idles great.... just WOT.   Should be easy enough. 

[Foxx4Beaver]

here's a couple good places for genuine Keihin jets...they know me well!

http://www.pjmotorsports.com/keihin-jets.html#pilot/slow%20jets

http://www.jetsrus.com/index.html

[cmotodad]

I am having a lean (ping) condition at the 1/4 to 1/2 throttle position. Stock n82m needle on the 2nd clip position. Larger pilot made the bottom sluggish and tough to get an idle. Tried larger main to no avail, just got fat. Anyone have a needle suggestion to help cure this? Thanks, Bob

[Foxx4Beaver]

see if you can locate an N82L or an N82K...the K being the richer of the two.

[cmotodad]

I will look for one. Has anyone used a JD Jet kit? Everything is good except the ping. Thanks

[DoldGuy]

Cmoto,

What slide # are you currently running? I have had a few bikes that no matter what pilot / needle combo I tried, could not get it to run clean in that 1/4-1/2 transition until I changed the slide (all of mine were Rich Conditions).

DoldGuy

[cmotodad]

Stock#7 slide

[DoldGuy]

If you have access to a #6 slide I would give that a try...

[Foxx4Beaver]

if you find you can't get your hands on a "good" used slide, try the needle....a new slide will be 3+ times as much as a needle...I always try to start with the cheapest things 1st.

[cmotodad]

Thanks, I will see where it leads me.

[alexander-vmann]

not sure where to post this but im hoping that since you all are talking about jetting someone migth be able to help, i got my 1993 kx500 a few days a go and it seems to run unclean on the mid range rpms, i think this migth be one of the jets are to lean/rich, any thoughts?

[Foxx4Beaver]

what needle and what clip position are you in?
your spark plug is an open book...it will tell you if it's too rich or too lean.

[alexander-vmann]

what needle and what clip position are you in?
your spark plug is an open book...it will tell you if it's too rich or too lean.

how can i tell if it is to lean or rich by looking at the spark plug? (im new to two strokes)