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blowfishct
03-30-2006, 03:09 PM
I got a 2004 400ex it had a FMF pipe on it and I put a white bros. pipe on is the jetting the same. I was told that the FMF runs leaner but I dont Know.
Yamahondaman
03-30-2006, 03:45 PM
we had a LRD Pipe on our 01 ex.. we changed the 148 main to a 175 main .. if yours "lean pops" when hot ... jet it fatter, bend the squirt arm abit behind the black cover to spray gas in earlier... keeps it from bogging from idol when stabbed
TravEX
04-23-2006, 10:54 PM
What jet is in it now? Probably around a 155?


Yamahondaman, 148 to a 175 for just a pipe seems like too much. Does it cut out at high RPM'S? What do you mean by "lean pops"? When you're decelerating? If so, that can be fixed by air/fuel screw adjustments. The "squirt arm" you're talking about, is it the accelerator pump?, if so, I definitely would not touch it, especially when the "bogging from idle" is probably a jetting problem (rich).


Blowfish, tell us more. Open air box? What air filter? And while you're into the carb, I would highly recommend getting a 42 pilot to put in. Really helps with cold weather starting and low end performance.


Later,

Travis
200xcellent
04-24-2006, 10:09 AM
You can get pops and backfires if your jetting is too rich also. Never assume your jetting is automatically lean if it pops or backfires a little. I wont have any popping or backfireing for a week or two then it will start doing it. I clean my airfilter and it goes away.
MichiganRedneck
04-24-2006, 10:17 AM
to jet mine, i just simply followed dynojets instructions. it was spot on. no guessing or playing with it after installation.
Yamahondaman
04-24-2006, 10:17 AM
Ours didn't "bog" on the top with the 178 .. i smooth tapered the back of the carb and also had a cone in the air box to except the TRX Filter, BIG Volumn !
also i gapped the valves at .002 ... helped ALOT !!
MTUz400nate
04-24-2006, 12:04 PM
Blowfish, all you can do is take it out and ride it after you put the new pipe on it and see how she runs. If it bogs and sputters on top then you are rich. If it pops on the top end and if you notice it running hotter then you are lean. If neither of these happens and it runs smooth you are probably alright.