A/F ratio on dyno?

[07ERider]

When you guys dyno your bikes what do you or the tuner shoot for A/F wise?


The only time I have dyno'd my bike the guy running the shop said he likes to see 12:1 which I thought was a little on the rich side but took his word for it since he was the owner/operator.

Anyways I recently sent my head to Rossier for some work and Joe told me my intake valves had lot of carbon on the backside which is an indicator of running rich. He said they like to see about 13-13.4:1 for safe max power.

Is this what you other guys are doing also?

[GPracer2500]

Originally posted by 07ERider
....he likes to see 12:1....
Sounds rich to me too. The only cases where I can see that being the best choice is with an engine that is having trouble staying cool at the power level it's making. This can happen with air cooled engines that are making lots of power.




...13-13.4:1 for safe max power....
That's much better. There's no reason to have a 450r running any richer than that.

[AutoRoc]

I'm interested in what A/F is optimal because I've yet to dyno mine. I'd bet it's a little different from my car's setup.

If you want to get into the tuning aspect, install a new spark plug and make 2 back to back pulls and pull plug. It should be easy to tell what it wants. Cut the threads and see how dark or non exsistant the fuel ring is at the bottom of the porcelin. O2 will let you fine tune it from there for sure. Goodluck!

[mcleod]

optimal air fuel is different on each engine.

you need a dyno to find the perfect ratio!

but generaly it's around 12.8-13.2 at WOT!!!