6 replies to this topic

[droptail]

What AFR's do the OE Gen 1's run at high rpm WOT?
Wondering if the inlet and exhaust are opened up,if they still want more fuel typically?

Thanks

[yamafitter]

I have never heard of anyone burning pistons or valves from high speed runs with the FJR so I doubt that the bikes are running lean at WOT. I am thinking one would need a flowbench and a spare head to figure out if any performance gains can be made by altering the exhaust and intake ports. Too expensive IMHO. UselessPickles has done the most work of anyone I know of on the forum with tweaking mapping and dnyo runs so I would shoot him a PM with your question.

[Fred W]

+1

The stock FJR fuel map is lean only in some areas of the map. In higher throttle openings it actually runs on the rich side.
This can be seen by looking at the PCIII correction values of just about any of their maps, or any correction maps created on a dyno.

Here's a look at the PCIII map provided by DynoJet for use on a lock-stock 1st Gen FJR with no modifications




Positive numbers are adding fuel, and negatives are subtracting it, from the base map, in percentage. This will give you an approximation of the stock fuel/air ratio without correction.

[UselessPickles]

If my bike was stock, I could have answered the question exactly with the data logger on my Motty AFR tuner, but my bike isn't stock. The best I can do is add to Fred's post by saying that 13.2:1 is the common AFR target for 100% throttle when dyno tuning a bike. The stock fueling must be richer than that since the PCIII map for a stock bike removes fuel at 100% throttle.

One theory for running excessively rich is so that you don't run too lean at full throttle after installing aftermarket slip-ons. It's like Yamaha knows that many people will customize their exhaust without being aware that they should probably get the fueling system re-tuned

[droptail]

I am just trying to get a feel of the direction I need to go with my modified intake/box & open exhaust (I plan to dyno in the near future).

Def needs more low - mid fuel, looks like the top end may need some more fuel too.

Thanks for the info.

[Fred W]

I am just trying to get a feel of the direction I need to go with my modified intake/box & open exhaust (I plan to dyno in the near future).

Def needs more low - mid fuel, looks like the top end may need some more fuel too.

Thanks for the info.

Describe your mods in more detail. We may have a dyno created PCIII map of that exact config to show you.

[droptail]

I am just trying to get a feel of the direction I need to go with my modified intake/box & open exhaust (I plan to dyno in the near future).

Def needs more low - mid fuel, looks like the top end may need some more fuel too.

Thanks for the info.

Describe your mods in more detail. We may have a dyno created PCIII map of that exact config to show you.

The stock air box is modified by drilling out rt side cover and cutting off left side snorkel, & removing inlet elbow.
Electric exhaust cutout on the pan before the cats, see below.
+10 on the CO.


Is the PClll graph above the result of what was required to make maximum hp at any given load & rpm? Is any consideration given to AFR during this process, or just getting the biggest numbers?
Is there a dyno here with stock AFR that I could compare to above with?

Thanks