Attak rich after exhaust mod?

[AttakDog]

I thought I seen a post about the Apex/Attak running rich after doing the exhaust mod. Mine seems to be rich especially off idle, and backfiring sometimes. What is the general opinion? Very leary about leaning it out for fear of burndown but was curious what everyone else is doing. This is with the cut out stock exhaust, not aftermarket.

 

[stoutner]

I thought I seen a post about the Apex/Attak running rich after doing the exhaust mod. Mine seems to be rich especially off idle, and backfiring sometimes. What is the general opinion? Very leary about leaning it out for fear of burndown but was curious what everyone else is doing. This is with the cut out stock exhaust, not aftermarket.

If it is backfiring after you let off the gas at full throttle, you most likely have an exhaust leak. Check the four donut gaskets where the header meets the Y pipe. If they are leaking, change them otherwise you will burn a hole in your pipe.

Also, what you think is rich is probably the exhaust leak. When mine was leaking, The engine felt "doggy" at low rpm's. When I put new gaskets in, it was a lot crisper.

 

[schmeg]

II was the poster for the pipe richness problem. I did check the pipe joints, and everything looks good. I took 20 units of fuel out at the pod and it cleaned it up a lot down low. It no longer smells like gas at idle, and when cold, it wasn't as fat and dirty sounding. Fuel economy still suffered which is expected, the pod only is good to 7000. I still feel that the pipe is giving a very strong sound wave signal to to exhaust port when the valve is open (which is what scavenging is all about) and without the corrisponding intake mods and fuel mapping, its running rich all over. I'm taking the pipe off this week and selling it just because I don't want to spend lots of dough to fix this issue, and the pipe is just too loud for my taste. It does sound nice, just not for my allready hearing impared ears. If anyone is interested, PM me. It has black panels, and has an 02 sensor bung welded in it.

 

[orange]

I just don't get it, if its increasing the scaveging and you are not putting more fuel into it, wouldn't you be lean?? I think you guys are hearing a lean pop, not rich. Have you ever checked the plugs> I have know on my zx12 putting a pipe on made it run leaner.

 

[SledFreak]

schmeg, pm'd you.

 

[schmeg]

The sled will load up to the point of fouling the plugs on cold startup. You can smell raw fuel coming out of the pipe. If you make exhaust scavenging more efficient, without telling the ECU the difference, it will continue to deliver the same fuel schedule. By opening up the intake tract (airbox) you compensate by increasing the airflow on the intake side, thus compensating for a rich condition. Problem is, most biox mods lean it out too much without the use of a fuel controller.

 

[AttakDog]

So the answer is lean it out??? Only seems bad at idle/low speed

 

[orange]

Seems azz backwards, on bikes you need to add fuel, weird for sure.

 

[schmeg]

Yes, lean it out if you have an otherwise stock setup. When you take out the fuel, it cleans everything up quite a bit. 15-20 units seems good. This only cleans up the bottom end. Ultimately, you should have a modded airbox and fuel controller.
BTW my fuel economy went from 16.5 -17mpg to 13 after I put the pipe on.

 

[woolyviper]

I just don't get it, if its increasing the scaveging and you are not putting more fuel into it, wouldn't you be lean?? I think you guys are hearing a lean pop, not rich. Have you ever checked the plugs> I have know on my zx12 putting a pipe on made it run leaner.

I second the lean pop theory. Four stroke is a different animal

 

[AttakDog]

I guess I'll just try pulling a few units out and see what happens.....I'll post the results, thanks for all the input