Yamah Apex with MPI Supercharger Air/Fuel Ratio?

[Sledingtime]

I have recently purchased a 2007 Yamaha Apex with a MPI supercharger and GEMS controller. Just wondering what I should be trying to get for an air/fuel ratio and that would be dangerous lean or rich.
Ive taken it out once so far and was averaging about 14.7 it would go above 15 and drop to 13 now and then. We were riding at about 2500 feet.
Any help would be much appreciated.

 

[ridehard1212]

Please chime in, , numbers should be around 11.5-12.5 to be safe and build most power..with 14+ getting to be on the lean side, and also robbing u of some power...

 

[BigFish BC]

14 would be ok at idle but would not want it anywhere else,it should sweep from say 13.5-14 to 11.5-12 at wot as you add throttle.

 

[Sledingtime]

Should I not be riding it at 14.7 then? Will it cause damage to the sled?

 

[ridehard1212]

my thought is that it might not cause damage, but u r on the edge of having a problem that causes damage... need to add fuel.. or may adj. elevation on gems therefore adding fuel..

 

[ridehard1212]

and by the sounds of it, no you should not be riding it at 14.7, u need to figure out where to add fuel to get that number down

 

[powdermuncher]

Anything above 13 to 1 you get into the dangerzone for detonation.

Good fuel will be your friend.

Lean air fuel around 13.5 to 14 to 1 is no problem at low power settings as vecor mentioned , but as soon as you start making power you should have it drop down to12.5 to 1 at max power.

 

[Scott1]

Don't ride with it running that lean, I'd add fuel at all the settings on the gems, also may want to check that sensor out, lucky you didn't roast her. The guys at mpi are more than willing to help, give them a call if you have any questions.

 

[SRXSRULE]

Here is my .02, When the sled is making Boost, or your at WOT you want to be 12.0-12.5

If its idling, or cruising at zero boost 13.0-14.5 is FINE. Cars/trucks run at 14.7 all day long.

The IMPORTANT part of this is making sure you are running the correct fuel for the boost and elevation. Eric

 

[pelon]

my apex ran its best at WOT @ 12 to 12.5
idle around 14.5

 

[ridehard1212]

he was running chevron 94 with 50% ish (5 gallons) of av gas... mostly around 3000ish feet.. 5lbs boost... snow was very set up so im wondering if possibly his numbers are a bit off from possibly over reving a bit due to track spinning???

i also agree that he probably needs to add more fuel.. but probably good to note that its unlikely that he had the sled much past half throttle very often as he is VERY green..

 

[BigFish BC]

this sled was set up for a higher elev right, now you are at a lower elev so its getting more denser air so its making more power so you need more fuel.iam guessing if you wack the throttle it will studder a bit if its lean.a 4stroke does not incure the same damage a 2 stroke will from being lean but extended used will do damage.if the gems box is the same as the prologic you should only have to add fuel the the last 2 circuit lights there is 5 if i remember right you mite have to bump up were you box starts fueling too if that box has boost sensing.

 

[Sledingtime]

The Gems box has the following changeable modes.

-Mode 1: Green – Idle / Cruise Mixture Level
-Mode 2: Yellow – Needle Enrichment
-Mode 3: Red – Main Jet – Set at 7.
-Mode 4: Green/Blue – Boost Fuel adder. The setting adds addition fuel to the fuel already being supplied in Mode 1,2 or 3.
-Mode 5: Yellow/Blue – Accelerator Pump.
-Mode 6: Red/Blue – Altitude compensation.

So I would assume I just need to up the settings in modes 2, 3 & 4. and that should richen it up.

 

[BigFish BC]

The Gems box has the following changeable modes.

-Mode 1: Green – Idle / Cruise Mixture Level
-Mode 2: Yellow – Needle Enrichment
-Mode 3: Red – Main Jet – Set at 7.
-Mode 4: Green/Blue – Boost Fuel adder. The setting adds addition fuel to the fuel already being supplied in Mode 1,2 or 3.
-Mode 5: Yellow/Blue – Accelerator Pump.
-Mode 6: Red/Blue – Altitude compensation.

So I would assume I just need to up the settings in modes 2, 3 & 4. and that should richen it up.

i would ajust the altitude comp some too i know it make a fair bit of diff with that.

 

[pelon]

my apex ran its best at WOT @ 12 to 12.5
idle around 14.5

Been tuning in my new nytro turbo and its much different:

No head shim
14lbs boost
91 octane
10000 feet plus
idle 14.5 +/-

WOT = air/fuel works best at 13.9 to 14.3. Anything lower causes rich bogging and power loss.-----go figure.

 

[powdermuncher]

Been tuning in my new nytro turbo and its much different:

No head shim
14lbs boost
91 octane
10000 feet plus
idle 14.5 +/-

WOT = air/fuel works best at 13.9 to 14.3. Anything lower causes rich bogging and power loss.-----go figure.

Calibrate your air fuel unit.

 

[pelon]

it is calibrated

 

[BigFish BC]

it is calibrated

what guage do you have & is the sensor still good how many miles on it seems lean.

 

[pelon]

AEM and 20 miles


its not lean, possibly a false reading though------??

 

[SRXSRULE]

You likely have an exhaust leak before your O2 sensor. Eric