LOW RPM hesitation with PCV and AT

[big_b]

I have been playing around with the fuel mappings and with Auto Tune ..

I setup Auto Tune to give me a AFR of 13.2 from 5% throttle to 80% and from 2000 RPM to 10,000RPM .. AFter 5% and 10,000RPM I increased the AFR to 13.

I entered zeros below 2000 RPM and for 0 and 2% throttle becuse Auto Tune was making it to rich there..

My problem now is when I take off from a stop it get spot between 1700 and 2000 RPM that it sort of stumbles .. and the motor "lopes a little" Should I increase the fuel there or does it sound rich? It also lopes up and down at idle.. but I have Two Brothers, NO CAT, K&N filter .. The dealer told me they all do this with aftermarket pipes ..

Playing around I have found that if I let Auto Tune increase the low throttle and RPM then the lope goes away but the rest of the bike is rich ..


I am thinking of manually adding fuel to the lower cells until it quits ..

Maybe I have already answered my own question.. what do you guys think ?


Thanks,

 

[Motogiro]

When the rpm lopes up and down like the dealer said it does with after market pipes, have you put your hand over one of the outlets and listened to the lope?

Try it and I bet it changes. Block off one can and see if the 1.5-2K stumble stops. Internal combustion is a science I only basically understand but there are many factors involved. Back pressure is one of them at lower RPM. There is also timing, cam lift and duration. When you pulled the CAT out of the line you opened the back pressure quite a bit. Some manufacturers have created a valve in the exhaust system that is computer controlled (ECU) that allows back pressure at low RPM and then it opens as RPM increases (more exhaust volume) to create a more efficient horsepower delivery.

In essence you've opened up the back end, leaving no back pressure at low RPM. I believe these type of valves are controlled with a servo motor that is operated by the ECU.

Exaggerated, the motor is sort of looking at no exhaust system at lower rpm....

 

[Hellgate]

Off the very top of my head I think you are still too fat at zero. If I recall correctly my map was -3 to -5 on the low end. (It's been a while since I've looked). I'll look tonight.

Giro is correct that if you have too little BP the bike will not idle correctly and can run funny at the low end.