YFZ450R Problems

[yfz450R-Panama]

Good evening,

I recently bought this quad and everything was running fine. Two friends of mine have the same quad also...I decided to take the spark arrestor out since they did it and supposedly it gives you back about 2HP...I took it out, and since then my quad is backfiring in first gear...and coughing 50% of the time that I am low reving. This did not happen to the other quads, I took the air filter lid off to see if that was the problem and same thing..


Any suggestions? The Yamaha dealer over here have no idea how Fuel Injection works and they refuse to touch my quad...sucks, I know.


Emilio.

[BrettOaktree]

most quads are lean from the factory and urs might be a little leaner than ur friends, and when u take the spark aresster out it gets leaner so thats why it is backfiring and popping and it gets leaner when u take the air box lid off so u need to get a programmer to change ur air to fuel mixture to a richer setting

[sparks 450]

f. I.- computer should allow for that.

[industry48]

I had the same thing. The fuel injection on all these quad's doesn't work like a car. It has no o2 sensor on the exhaust so it can't make the right corrections. You need a power commander to remap the system. I put one on mine and it made a world of difference the one from GYTR comes with four maps and I took the one for the exhaust and intake and I played with it a little bit to make it work perfect with the lid off and the spark arrestor out. I can upload the map if anyone needs it.

[tyhackman15]

Originally posted by sparks 450
f. I.- computer should allow for that.

not to be a d*ck but make sure you know something before you post. If somebody followed that advice and ran a pipe/intake with stock FI it would be bye-bye motor in a few hours.

You need to re-tune, it's one of the downsides of FI (i have an LTR and thank god for the CRBM being $20, i don't know what is out there for yamaha)

[h&h]

get a powercommander 5 and u will need to tune it on dyno and u will be set to go man:)

[yfz450R-Panama]

Thank you all for your answers.

So basically, I need a Power Commander V? I understand this helps me to tune my bike according to what I have. Is it necessary to get the Auto Tune also? DO I need Auto tune to use Power commander V on my bike?

It makes me wonder why Im needing the tuning device if I haven't changed anything really....



Cheers!

[toby400ex]

Originally posted by yfz450R-Panama
Thank you all for your answers.

So basically, I need a Power Commander V? I understand this helps me to tune my bike according to what I have. Is it necessary to get the Auto Tune also? DO I need Auto tune to use Power commander V on my bike?

It makes me wonder why Im needing the tuning device if I haven't changed anything really....



Cheers! If removing the core to your silencer actually does anything it is because it is allowing more air to move through the intake motor and exhaust system. If that is the case your fuel injection system (which has no o2 sensors) is dumb, it wont react to the changes you made, if you're moving more air you will have to make the fuel injection system move more fuel also... plain and simple

[yfz450R-Panama]

Originally posted by toby400ex
If removing the core to your silencer actually does anything it is because it is allowing more air to move through the intake motor and exhaust system. If that is the case your fuel injection system (which has no o2 sensors) is dumb, it wont react to the changes you made, if you're moving more air you will have to make the fuel injection system move more fuel also... plain and simple

I know, but I've never tweaked a fuel injection engine before, only carbs. I dont even know what to move. If you know which part on my yfzr Im supposed to move, then please tell me, if not, the only solution would be to get the powercommander. Imo

[tedwilley]

The Power Commander is the only way you can tune the bike. There aren't any adjustments, other than programming.

The EFI can adjust for altitude because there is a mass air sensor, but not for intake or exhaust mods. Those alter the volume of air through the motor and need an Oxygen sensor to feedback the fuel mixture to the EFI. Even EFI on most cars can't adjust for intake or exhaust mods adequately.

The auto tune is an extra module and Oxygen sensor (must be welded into the header) that would allow you to tune it while riding the bike. But it has a slight learning curve to get it correct, so I understand.

Just the standard maps that come with the PC (one is for a new pipe and air box lid removed) should get you pretty close.
To be dead on through out the RPM range you should have it dyno tuned.

The PC is programmed by using a laptop with a USB cable.

[daddio]

Check the bolts that connect the pipe to the head, to see if they are loose. Also check to see if any exhaust is blowing out from around the head pipe (bad gasket). Also look for cracks in the head pipe.
If all that looks good, check the intake side for leaks.
And check the plug cap to make sure it's on nice and tight.
Maybe even try a new spark plug.

It should run just fine with just the air box lid and pea shooter removed. A little lean, but ok.

[sparks 450]

Originally posted by tyhackman15
not to be a d*ck but make sure you know something before you post. If somebody followed that advice and ran a pipe/intake with stock FI it would be bye-bye motor in a few hours.

You need to re-tune, it's one of the downsides of FI (i have an LTR and thank god for the CRBM being $20, i don't know what is out there for yamaha) he didnt say he put a pipe and intake system on it duh. he only took the baffle out first and tried it with the air lid box top off next. so what is really the advantage of efi over carb if you have to buy fuel commander for any little thing you do. it sounds like people would be better of buying a 3 dollar jet.yamaha should of been smarter than that and did what suzuki did. he could of reinstalled the baffle and lid and if it stops popping then he would have his answer. efi better fuel mileage - more weight electrical nightmare. higher cost. and why didnt his friends quads do the same with the same mods he has.

[450rJam]

you can buy two brand new quads exactly the same from the same dealer on the same day and put the same exact mods on them both, then take them to a dyno and they can need different maps or jetting

put your airbox lid back on (or your going to be really lean and toast your motor)

check the joint where the header meets the head (a slight leak will cause alot of popping when you let off throttle)

you said just in 1st gear under low throttle ?

what yamaha dealership is this that refuses to work on your atv?