Yamaha R3 Forums banner
1 - 5 of 5 Posts

·
Registered
Joined
·
37 Posts
Discussion Starter · #1 · (Edited)
Title. I'm thinking about picking up the akrapovic GP full system and running it with the baffle in (currently running stock exhaust with the can removed as a quasi underbody) and was hoping somebody might know if it'll lean out the AFR at all? I've heard anecdotally that supposedly it will, and as the bike already runs fairly lean stock I'm not too keen on the idea of scorching valves or heaven forbid knocking the motor to death. I wouldn't think that anything exhaust side would change how the bike runs, but in case I'm wrong I figured I'd ask here. A power commander will be coming around the end of the year, and no I'm not interested in a different exhaust (well, except maybe the M4) or the stock exhaust. I heard and Akra R3 at work yesterday and it sounded so bloody nice that I NEEEEEED it. Provided I can run it without a tune that is.
 

·
Registered
Joined
·
346 Posts
Would it? Probably - probably not a ton - need to look at manufacturer recommendations - yoshimura's full exhaust with baffle in is supposed to be on stock ECU (they still have issues). You'll likely loose power without tuning and it won't run great but could work.

Changing anything exhaust side on a naturally aspirated motor would change how it runs.... An engine is nothing more than an air pump, you're reducing the restriction on the exhaust which increases efficiency and pump more air...
 

·
Registered
Joined
·
78 Posts
I find this HILARIOUS. for some reason motorbikes narrow band sensors somehow lose the ability to maintain 14.7:1 with an exhaust. its really funny!

cars run the exact same narrow band and can handle an exhaust/airfilter change no problem! Bikes do as well. except for everyone who peddles this fear mongering to sell bazzaz/ powercommander.

and then every customer who continues it!

your bike run the base level narrowband tune of 14.7:1 ratio Yes granted its not the best for performance. But the stock injectors can if you think about it. if you run a power commander/bazzaz on them can drop it down to a rich 12:1 on the exact same hardware.
the stock computer with those very same injectors can by proof maintain that 14.7:1 by freeing up the air intake and the exhaust flow EASILY
 

·
Registered
Joined
·
346 Posts
I said it'd run, just not optimally didn't say it wouldn't start or some ****. Even in a car, not best to do on a narrowband but your motors, do what you will.

For the record, 14.7:1 is stoich which is optimal idle, not optimal under the power curve, actually Jesse found optimal AFR's in the 13's - probably running 12's stock (would have to ask him, couldn't find data on it) under load.

Here's results of bone stock bike then adding a full exhaust and exactly what it did, notice how his conclusions are the same - with real world testing? But what do I know, you're here to prove us all wrong all the time :).

http://www.yamahar3racing.com/category/dyno-testing-and-tuning/
 

·
Registered
Joined
·
1,206 Posts
Yes you can run a full exhaust without a tune, but why?? It won't be anywhere near optimal, it'll run lean (as it already does from the factory), and won't really gain you any benefit. If you're going to do it, do it right and either get a fuel management system or an ECU flash when you get the exhaust.
 
1 - 5 of 5 Posts
Top