Suzuki Central Forum banner
1 - 13 of 13 Posts

·
Registered
Joined
·
40 Posts
Discussion Starter · #1 ·
I am going to be tuning my KFX on the dyno next week and i wanted to know if anyone has tuned using a wideband O2 sensor to tune to the perfect air fuel mixture while on the dyno ? if so what is the optimal O2 reading to be at ? i know that 14.7 is stoich but is it the best point to make power on a quad ? mods are listed below , thanx for you time and any help would be great .
 

·
Registered
Joined
·
970 Posts
The best ratio for a naturally aspirated motor is at about 12.8:1 to 13:1 at peak torque. You can go up to about 13.25:1 at the higher and lower RPM's, but since these quads have carbs, you probably won't be able to dial it in as nicely as EFI.
 

·
Registered
Joined
·
1,174 Posts
Why not use an exhaust temperature sensor?

From what my I.C.E. Professor told me, it'll be around 1200 Degrees F (which really depends on where you place it)
 

·
Registered
Joined
·
365 Posts
Not sure if it was a wideband or not, but I had mine tuned on a dynojet dyno last night. Mechanic just called it an air sniffer. Mine shows an air fuel mixture of 12.2 at peak torque. Does that mean it's slightly lean or rich?
 

·
Registered
Joined
·
365 Posts
Thanks Barely Legal, I went back and compared the last 2 runs. On my quad the richer settings gave me 0.9 more horsepower and 0.2 more torque. Not trying to flame anyone, but mine got better numbers with the air/fuel mix in the low 12's. The 12.8 - 31.1 range gave me a little weaker run. Could it be that these numbers vary from dyno to dyno just like the horsepower numbers do?
 

·
Registered
Joined
·
1,174 Posts
QUOTE
The best ratio for a naturally aspirated motor is at about 12.8:1 to 13:1 at peak torque.  You can go up to about 13.25:1 at the higher and lower RPM's, but since these quads have carbs, you probably won't be able to dial it in as nicely as EFI.[/b]
how 'bout if you use a "dial-a-jet" ?

Has anyone seriously tested those things?
 

·
Registered
Joined
·
1,174 Posts
QUOTE
Thanks Barely Legal,  I went back and compared the last 2 runs.  On my quad the richer settings gave me 0.9 more horsepower and 0.2 more torque.  Not trying to flame anyone, but mine got better numbers with the air/fuel mix in the low 12's.  The 12.8 - 31.1 range gave me a little weaker run.  Could it be that these numbers vary from dyno to dyno just like the horsepower numbers do?[/b]
When idling and running WOT, you should run rich. In the middle throttle settings, you should run slightly lean.

That's according to a basic calibration table I got from my I.C.E. class
 

·
Registered
Joined
·
141 Posts
HPF Man,
What jets did you end up running????
Are you near sealevel?
How much hp over stock?
 

·
Registered
Joined
·
365 Posts
Badfordman,

Ended up with a 165 Dynojet main. I looked at a cross reference and that's about a 152.5 or 155 Mikuni. Needle on 2nd notch. Air screw at 3.5 turns. No airbox lid. Elevation here is 700 ft. Hope this helps. Had a 6hp gain.
 

·
Registered
Joined
·
141 Posts
HPF Man,
Did you change your pilot jet?
Is that 2nd groove from the top or bottom?
 
1 - 13 of 13 Posts
Top