What is a 2valve Ducati's IDEAL fuel / air ratio?

[lwszabo]

searching dont turn up anything. M800 ie if that matters....best fuel air ratio for the safety of the engine.  I **think** mine was in the 13's with stock airbox lid, Sil Motor exhaust, and PCIII

also if I am in the 13's could I affort to put on a open airbox lid with no negative effects to the engine?

[Raux]

not sure it's really a static number. varies with engine load, throttle position, speed, rpms.. etc. that's why fuel maps are so complicated.

[koko64]

I wouldn't run an open air box without getting the bike tuned for it. If you are already in the 13s on air fuel ratio with the stock air box you would be unwise to to open the air box and lean the bike further.

Raux is right. Get the fuelling tuned for max power on a dyno when you open the box to allow for the engines requirements at different revs and loads, etc.

Check out the bikeboy site for dyno and tuning info to guide you.

Cheers

[battlecry]

Koko, 13 is rich. 

[uclabiker06]

Yeah, if your going to modify air box then you need to modify fuel/air as well.

[ducpainter]

Koko, 13 is rich. 

Yes,

but probably not rich enough for an open airbox.

[lwszabo]

Yes,

but probably not rich enough for an open airbox.

I found a chart online 13 is the best power ratio, 14 best milage ratio, 14.7 perfect.  I was also told the numbers vary at every extra rpm, and perfect may only be for  asplit second. I was told my bike is right where it needs to be. It rides alot better, I just wish i would of chopped the airbox and tuned it for that...my new Pilot powers didnt like that dyno!!

[supertjeduc]

13 is not to rich , mine is now at about 13.7 and it's perfect
But can't you tune it with the pc3 if you want an open airbox (don't like the sound of an open airbox ,pods are much nicer)

[lwszabo]

13 is not to rich , mine is now at about 13.7 and it's perfect
But can't you tune it with the pc3 if you want an open airbox (don't like the sound of an open airbox ,pods are much nicer)

I could but then i dont have  the thing you stick in the exhaust to see what the changes did.

[koko64]

Koko, 13 is rich.  

I understand your point battlecry, and no offense taken. The air/fuel ratio was in the thirteens.
I think the air/fuel ratios should be checked via dyno/EGA when you make a major change to the air intake like removing the air box lid.

More than one dyno operator has advised me that it depends on how the dyno EGA equipment actually measures the air/fuel ratio, and to not be fooled by the 'magic' 14.7 : 1. They were looking to see about 13 : 1 and then would look for max power given the load for cruise and acceleration, smoothness and rev range, etc, so the ratio could be anywhere between 12.5 :1 and 13.5 :1 (and that's not set in stone). And that's before you take fuel into account.

I only base this on the advice from at least four different dyno operators/tuners who have helped me out. For example, tuners have to consider things like the theoretical numbers verses maximum power under load, engine smoothness , throttle transition, and economy at a steady cruise. I would recommend Patrick Burns article on Keihin FCR carb tuning  and his discussion about measuring air/fuel ratios via CO levels. It's a great article and gives some good advice on tuning in general.

An eminent tuner of superbikes in Oz (Phil Tainton) tuned a superstock level superbike (YZF 750) for me once. He showed me what looked like excellent dyno graph/EGA numbers. He told me to test ride it first and bring it back because he suspected it would not be as good for the rider as another jetting option that gave Hp graph and EGA ratios that were not closer to theoretically perfect. He was right, the way the power came on didn't match the promise of the theoretical numbers. He used the other jetting set up and the bike was easier to ride. Part of me wanted to stay with the theoretically excellent dyno/EGA numbers because they would look good showing my mates over a beer! Problem was the bike performed better the other way and it messed with my head a little! In the end I used the alternative settings and sanity prevailed. I'll never forget that lesson.

Mind you, I have also read somewhere not to get confused by the different ways of measuring the air/fuel ratio, something in relation to measuring mass verses volume of air/fuel I think. This could possibly be a source of confusion. Someone qualified with the theoretical understanding will have to explain that and correct me if I'm wrong. I'm just the guy that rides the bike and changes the jetting after consulting the dyno guy/tuner.

So the bottom line is get the bike's A/F ratio checked and tuned for the open air box mod if you do it. And beware the 14.7 : 1.

Cheers.