yes the air injection was still connected using the meter but klxster said my readings was the same he got on the dyno and he doesnt have that stuff connected

So if we both had the same readings I dont think that was the issue

the probe was around 16 inches long

this is what the guy had bought originally and its only like 8 inches long the o2 screws directly into it
but this is more for car exhaust pipes just clamps on with a set screw



but for small bike applications this wouldnt work as is
I said to mount it on the muffler with long springs but they ended up making what I used

 

I'm thinking PAIR valve injection systems (like ours) can't flow air into the exhaust during acceleration or steady state as in sustained WOT.

 

the pair valves I have taken apart on other engines push air through a pretty small hole
only reason its sort of large outside is to fit on a standard hose
and im sure larger engines will have a larger hole but 250 isnt that large

it should work everytime the engine runs
but I bet it only pushes so much air, probably for idle to keep the emissions readings down since im sure all the tests are at idle which is why they lean out the pilot jets and block off the air or fuel screws

im guessing once your driving its then not even helping any as the tiny amount of air it blow in is nothing compared to the amount of air going out of the exhaust

 

From a little more research:

When you close the throttle, as in gearing down or slowing down, the drop in vacuum at the intake port allows the Pair Valve to relax and open and allow air from the air filter box to be "siphoned" into the exhaust port by the negative pressure at the exhaust ports. (there are reed valves in the pair valve to prevent backflow from the exhaust to enter the pair valve and airbox during roll-on and subsequent positive exhaust port pressure).

AutoShop101 web page on PAIR valve injection - it operates only during cold engine warm up and deceleration...

There are a few other PDF's on the functioning of the PAIR air injection system that also indicate the system only really injects when outside/ambient air pressure is greater than exhaust pressure. During decel is the goal with more sophisticated systems capable of cold engine warmup operation...

Again, I think this is why your AFRs are the same as mine and why removing the system as well as enrichening the idle circuitry mitigates decel popping..

 

Question for the jetting experts. I have two KLX250s. One is a 2012 "S" and the other a 2009 "SF". Both have about 1300 miles on them. I am at sea level in a hot and humid climate. Both bikes are using DynoJet stage 2 kits with 128 mains and the needle at 3rd notch. Screws set to 3 turns out. Snorkels removed on both. New stock plugs on both.

The "SF" has an FMF Q4 and an FMF power bomb and runs amazing. Cold starts only require 30 secs of choke and no decel popping. Very smooth throttle. Couldn't get any better.

The "S" has a Two Brothers M7 and an chinese knock off powerbomb. It runs good but needs much more choke in the morning and has a slight bit of decel popping. Nothing too bad though.

Is there anything you could suggest to make the "S" run like my "SF"? Is the TBR exhaust flowing so much more that I should need to back the screw out another 1/2 turn or up the pilot or main jet?

 

boatdriver1790, are you a maritime capt..? I spent a little over a decade in the Gulf capt'ning..

My dyno testing indicates that the exhaust system configuration has a significant affect on the AFR produced by the CVK. The TB-M7 and Chinese PB may not be mating up very well due to I.D. differences.. If there is a restriction presented to the exhaust flow at the header/slip-on junction,,, you have a problem...

Decel popping is a leaking exhaust port to header seal - a lean pilot circuit - or both.
So do this - check your seal.. Pull on a little choke as the bike is decel popping - if it stops, the pilot circuitry is too lean.

 

I had decel popping due to a leak between the header and silencer.

 

Klxster,
Thanks for the info. For now I've backed out the screw to 3.5 and it really seems to have helped the start ups. Haven't ridden yet though.

The header actually fits perfectly with the TBR exhaust. Very tight fit and I doubt I have a leak there.

As for being a commercial captain, not just yet. Although I do have my 100 ton masters. I'm actually active USCG. Just passed twenty years of service!