jetting for exhaust

[hondamano4]

i have a 2008 yfz450 and i am putting on a exhuast. i need to know where u guys think the jetting should be at. what i have is FMF Powerbomb header and FMF Fatory 4.1 exhaust. so where do u guys think i should strat on the jetting at. what size of main and slow jets where should the clip be at on the needel. OH YEA it is all stock except for the exhaust.

thanks Eric

[KENNY HEMMINGS]

Air box lid has to go or be drilled with holes, you have to have more air, get a GOOD AIR FILTER! then buy a GYTR jet kit from your YAMAHA dealer it has your mains,pilot and needle in the kit, if you were in the south I would tell u to jet it like i have mine but where your at you will just have to do some tinkering with it? I have tried some other jetting kits but I like the GYTR kit the best,and you will also have to adjust your air-fuel mixture screw, you will have to pull the bowl off the bottom off the carb the 06 ups have a alm. plug that has to be knocked out off the bowl to get to the screw to adjust with carb on the bike or to screw in a
aftermarket air fuel mixture screw???? this may help you some. :eek2:

[hondamano4]

yea that is the jet kit i got now but iam at 180 main now. it still want to bacffire and it it lose powe in mid RPMsor cuttes out. i dont know what else to do. hanks for the help.

[KENNY HEMMINGS]

Down here i run a 175 main 48 pilot, clip in the middle on the needle and 2 3/4 to 3 turns out on screw I also run the boyseen power shot or quick shot whatever they call it, now thats with no air box lid and gytr filter and adaptor.