It's high time we all stop running our bikes lean. A CVK main jet change (bigger) does not cause your bike to putt around town rich. It will only cause your upper end (7-10.5k) to perform better at WOT (wide open throttle) unless your main jet is so big it actually causes the top end to go too rich - which is not even possible with the DJ kit, near sea level. My specially ordered DJ #136 is about right at 12.5:1 at the upper end.

Now for us power junkies, the needle, float height, and pilot circuitry must be richened next - after we've done all we can do with the main jet. Memorize the CVK Setup Procedure link on my signature line..

 

Neoarc, you are on the right track - the article your reading should be gospel for setting up the CVK. As you know, getting that main jet correct is the first step. Don't worry about that dead spot yet. I would have expected the 132 to be pretty rich - but only at 7-10k rpm - at your elevation.. What you end up with will be of interest to members at higher elevations..

 

Thanks, Klxster. I've been meaning to post my latest results. I couldn't been more happy with the 132/4n set up. The throttle response is excellent and much better than the standard 128/3n stage 2 set up. The header doesn't get near as hot as before so I'm obviously running a bit more rich. Overall, this is a great step up from Stage 2.

 

Boatdriver, I intend to now start in on the needle tuning (5.5K - 7k RPM) as per the article on my signature line.. I guess I'll start with seat-o-pants testing of 5N as the 4N is still lean..DJ claims their needle is designed to work at all clip positions and won't affect AFR below 3k RPM.. Perhaps I can unlock some more power as I get my CVK dialed in ...

 

I put in the 128 main today, I also pulled the carb and set the float height, which was low. I had the #35 pilot at 2.5 turns, now at 3.

Klxster, my bike feels exactly as your last dyno run looks: very below 5k, then kicks in at around 5.5k-6k, then really kicks in at 7k and up.

128 vs 132: same top speed in a 200 yard run, 128 is more responsive from 6k and up when going from part throttle to WOT.

Bottom end from 3k to 5k is improved, no bogging down any more, but still no where near as responsive as the mid and top range. Is this normal due to lower HP at that rpm? Any mods specific for this rpm range that wont hurt 6k-9k?

 

Firstly, it is fascinating to hear of your results! Lets work on that 3-5k a little.. I'm gonna go look at the only good chart I know of, on a stock bike, to get a feel for WOT power delivery below 5k.. Be right back.. Ok here is the chart-http://kustom-kraft.com/files/KLX250...rt_6_22_11.pdf ignore the big dip in the TRQ curve (old) .. Looks like TRQ is building at 3-5k but peaks up near 7k.. So your high altitude is going to make less TRQ and HP than normal.. Perhaps that is the nature of your beast then.. Just be sure you are getting all you can from your carb from 3-5k at WOT as per the instructions in the tuning article...

Now if your "dailed in" perfectly on the CVK and still want more under 6.5k - you can get it with the MCM mod.

 

I backed the fuel screw down to 2 turns, from 3. It's much better now.

I've read the factorypro jetting guide and I understand, I think. But does any one have any specific real world tests to determine the condition of the jetting? Obviously there's the WOT time run. I've also tried the backing off from WOT to 7/8 throttle. Cruising at 4k rpm in 4th gear is also mentioned in the factorypro guide. Any other tests I can run?

My idea is to run the 128 for a week and run some tests, get a good feel for it in my commute as I already ran the 126 for a week, then switch to the 126 again and run the same tests. I should have done it before switching, but I thought the difference would be clear but they are just so close together in performance.

 

If your dialed in while using the 128, the switch to the 126 could be transparent - no change discernible or detectable..

I believe simulating a dyno run would be the way to go - choose a gear - say 3rd or 4th - Steady at 3.5k rpm , snap to WOT, time how long it takes to reach a target RPM..

 

I was going to ask if it should be a target RPM or speed, but it's really the same thing within the same gear. I will try out both gears to see which is a better indicator.

I agree their may not be a much difference in the 2 sizes, specially from 7k up. i think the main difference may be in how the main feeds the needle from 5.5k to 7k. I'll let you know the results.

Either way, I'm very happy with the results. Thanks again for posting up your research and dyno sheets. I think they are a big revelation for most. I'm eager to see your results with the needle in 5n or 4n.

Cheers,

 

Remember Neonarc, while the main jet does affect the AFR of all the other components, it is solely responsible for the AFR from 7k on up.. But as you can see on my charts, it took going from a 132 to a 136 to get from 13.5:1 down to 12.5:1 up past 7k.. That is why I'm curious if there's any noticeable change as you do the 126/128 dance..