As I have stated to you at least 100 times already and apparently you are not comprehending or refuse to believe The reason the bike starts easier with a slightly open throttle is because a fully closed throttle limits the amount of compression your able to get combined with the use of a decompressor mechanism. Opening the throttle slightly allows more air in the cylinder, restores the compression significantly (despite the de compressor) and with the additional air pressure in the cylinder makes starting easier.
Your bike starts easy without cracking the throttle because you modified the decompressor pin when you installed the YZ cam and I am pretty sure you live at a lower elevation than most people who are having problems.
I suspect that the mixture goes leaner off idle because either the ecu is changing maps from idle to off idle or the TPS
may need a slight adjustment.
It is possible that your readings are on the rich side because your AFR gauge and sensor may not be grounded correctly. I had the same issue on a supercharged truck I had installed gauges on once upon a time
And even if my bike is running rich and the gauge is accurate, who cares?
I used to be OCD like you about stuff like this but in the bigger picture, the bike runs great! Why go to all this trouble? Why put all that crap on your bike?
How about you find yourself a nice trail and just ride the damn thing?
I'm heading out this next week and I'm going to enjoy my new yz450fx I loaded one of the maps I found here on TT which added some timing and fuel to my tune. The bike hauls ass! I can pull wheelies in 4th gear!
And I couldn't give 2 shits what my AFR is!
Now the tune on my 6.2 Sierra with a supercharger, that is a totally different story!
On my bike, I can get 70 miles out of a tank! More than enough range for me. When I ride I pay attention to the terrain, improving my skills and most importantly having an AWESOME TIME riding. I take my bike out to relieve the stresses of life and enjoy the time with my friends, forget about work enjoy the scenery and the very last thing on my mind is "is my AFR too rich? Is it stoic? Is it not exactly perfect?"
You know what? The ONLY time I worry about my air fuel ratio is when I fly airplanes! If you've ever been in one you would note that even the fuel injected engines require you to manually adjust the fuel flow from startup to cruise. Because in an airplane you change altitude all the time, you consequently have to change the fuel flow.
In an airplane we use cylinder head temperature on an air cooled engine to determine if we are running too lean or rich. Then to make matters worse, for fuel economy reasons you can run the engine what's called "lean of peak" meaning you run the engine lean to the point the cylinder head temp peaks, then lean it more until the temperature drops another 50 degrees lean of peak. At this point the engine is running very lean, so lean that your on the edge of stalling the engine! "The worry you would be experiencing at this point might just put you in a state of panic!"
I could just imagine the total state of panic you would find yourself in if you were a pilot because airplanes don't have any AFR gauges!!! Imagine that! Can you believe that an airplane who's engine running so perfectly to keep it aloft and purring like a kitten has no means of keeping the AFR perfectly stoic and a fuel mixture knob that you can pull and push a distance of about 4 inches would drive a guy like you completely insane not knowing if your too rich or too lean! Your engine might not be making the maximum Hp or getting the best fuel economy!
That would literally eat you alive I can see it now...
When I fly I need to make sure of 2 things, 1 engine is running smoothly, 2 is it rich enough while I'm doing my approach to land that if I have to abort the landing and go around again that it won't stall if I need full power when I abort. If I am in a carburetor plane do I have carb heat on and how much too rich will that affect my setting at this altitude?
You see the range of fuel ratios can be between 11-16 and still keep the engine running smoothly and making good power.
Are you working for the EPA or something?
Or are you just the nerdy type with a heavy dose of OCD mixed in?
Dude! You going to drive yourself bonkers and go broke looking for that last bit of performance and fuel economy that a dirt bike simply was never meant to have!
Now that you've come back to reality.. Trust me the AFR ratio between lean or rich doesn't make that much difference for performance especially on a WR and most importantly I'm sure at your skill level you probably just putt putt the thing around on a trail or a road it seems where you never even come close to using half the power the bike has anyway!
Try this.. Put your tools away.. Forget about fuel ratios, enjoy the fact your bike starts up on the first push of the button. Go find a trail and ride your bike and just enjoy it. Let all your worries melt away!
Edited by Bass Mechanic, January 30, 2016 - 04:38 AM.