Translating RPM to fraction of throttle

[DKGS850]

Dear all,

I have an Air Fuel Ratio meter connected to my bike, and that shows me my Air to Fuel ratio at a given RPM.
All of the guides describe if it is the pilot jet, needle jet or main jet that is affecting the combustion at a given amount of throttle (1/4 throttle, ? to full throttle, etc) but I cannot record that in my AFR meter.

Is there any way to translate an RPM reading to a certain amount of throttle? Perhaps just in second gear, or something like that?

Thanks in advance.

Best regards

Michael

 

[Big T]

Two pieces of tape - one on the throttle, one on the switch pod

Mark across both - closed, fully open
Now mark switch one with 1/2, 1/4,3/4

 

[rphillips]

I'd think that would be a problem. If in second gear, at 1/4 throttle, on flat rd. you get, say 5000rpm. you start down a slight gradual slope it may go up to 5500, then down a steeper slope may be 6500, then you start up a gradual slope & it goes to 4200 rpm. then up a steeper slope may drop to 3000. I've never thought about this before, but I'd think a Dyno may be the only way to get an accurate reading of what you're looking for. Just my opinion.

 

[RichDesmond]

To really do what your asking, an eddy current dyno is required.

 

[DKGS850]

Dear all,

Thanks for the replies. I was afraid that it wouldn't be possible to do a general translation, but perhaps someone had done a translation for e.g. "flat road, 3rd gear, stock jetting", and mapped that.
I did try Big T's tape trick, but that does not get recorded the same way as my RPM's does, so if there were a a formula for converting RPM to throttle, it would make my desktop analysis a lot easier

BR M

 

[Steve]

Try this so you can see how irrelevant that would be.

With the bike in neutral, turn the throttle up to 1/4. Note how quickly the engine speed twists the tachometer around and bends the peg that is beyond the redline.

After you rebuild the engine, put the bike in third gear at about 20 mph, turn the throttle up to 1/4. Note how you can use a calendar to track your acceleration.

There is no way to relate throttle opening to engine speed unless you apply a known, REPEATABLE load.

.