Yosh Exhaust + 2010 YZ450F = Mapping Changes?

I searched around, but the only thread I found close to this would have been a 2+ year old necro thread, so I didn't want to bring it back from the dead. I just installed a Yosh RS-4 pipe (slip-on) on my 2010 YZ450F, and I love the difference it made! It's almost like getting a new bike all over again. I have noticed a bit of difference in how it runs, and though very slight, it is noticeable. With aftermarket pipes and fuel injection (this is my first EFI bike) should I need to adjust my maps? It seems like I need to lean it out almost on the bottom because I am getting a slight hesitation with hard acceleration from down low. Anyone else have experience in this area?

I'm running the FMF 4.1 slip on, on my 2012 yz450f. I just run the "Marmont" map and have had no issues. Your so right about how the bike feels/performs. its not really faster, but revs so much quicker and has a bit more noise..lol

congrats on the pipe the yosh systems are a work of art!

Use the map I posted in the efi tuner thread, I,ve tried them all ,then made my own, which is the last map posted in the efi tuner section. I've put that program in about10 yz in san diego area, all liked better than any other listed.the stock map is rich.

My 2010 with RS4 slip-on runs really nice with both the gyt-r "sharp" tune and the "marmont" map. After lots of hours I like the marmont map the best, it seems just a little snappier than the "sharp". The sharp map seems a little easier in tight, slow, tech trails, but I like how the marmont map feels a little bit quicker to respond to throttle movement. Play with those two maps and see what you like. I was stuck on the sharp map for quite a while until I swapped bikes with my buddy one day and thought "damn, that thing is a little more responsive!"

Yeah I have been using the Marmont map. I suppose I should have mentioned that!

run some better gas

Really? I run Chevron/Shell/Phillips 66 (top tier gas companies) premium at all times. I can't imagine getting a pipe requires me to run race gas...

I took my bike out for the first time this year and the first ride with the Yoshimura full system and the good traction/slippery/hard pack map and it hauls ass! I didn't take it on a track just up and down the gravel road but it seems to be a big improvement over the stock pipe and easy hit set up I had before.

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