Yet another jetting question

[stabor1122]

Well I pulled the carb today and checked the jetting. Holy crap....it had a 230 in there. I have only ridden the bike once since I got it in September and I do remember it seeming to be running lean. It would rev on it s own. Anyway long story short I am getting it ready for this season and finishing the last few things that its needs. From everything I have read I was thinking I should probably be around 290-310. I have a few spare jets but unfortunately none in that range. The closest I had was a 270 and 340. I figured the 340 was going to be way big so I put in the 270. Going to button it back up for now and pick up some more jets this week. My question for those of you who are pretty good at guessing on the jetting is how close do you think I am now. Obviously plug chops will tell the story but I want to get as close to right as I can first.

Current setup:
Stock carb
Unifilter-No lid-Stock Box
Boyesen Dual Stage Carbon Reeds
FMF Fatty and Powercore 2
Stock bore with no porting or head work

 

[acezeesawtooth]

300-310 at least bro...

 

[blasterboy91]

you can get away with a 270 for a bit...All you really have is a FMF pipe...and 90% of people have success running 260-290

 

[acezeesawtooth]

^^^ yeah but he has the lid off and thats gonna jump him up another couple sizes

 

[Blaner]

i would maybe try a 290, but you have no porting so it may too much. you not far off the mark, but id go a little bigger to be safe

 

[stabor1122]

Cool. Yeah from everything I read I thought that the 290 would be the place to start. But I will probably also pick up a 300 and a 310.

 

[98blaster+4]

you should throw that 340 in and see what it does . i had almost the same mods as you and used a 320, with the lid off can make a big diference in your jetting. whats you altitude? and the temps you usually ride at?

 

[stabor1122]

Not sure what the altitude is. I am in Ohio. Temps when I ride will vary from the 70-95 in the summer when I ride.

 

[little3mil]

just start one or two sizes fatter than you think and do proper plug chops, it takes many times taking off the carb and switching jets to get your bike dialed in. once its done you'll be happy tho, remember every bike is diffrent

here is my trail bikes plug after a very proper WOT plug-chop, this is about as dialed in as it gets with no air leaks, you want that light brown ring when you cut the threads off

there really is no color to the plug (very light brown) because its perfectly tuned, if you have any black, wet, build up or anything on the strap then your losing performance

 

[Awk08]

300 max, 290/270 will be about right
300 main in my sons, it's on it's second season with no lid, uni filter, f7, then lrd right bend pipes, stock carb, very mild porting/cleanup
the fmf generally requires a leaner jet than the right bends

 

[Busted Warrior]

I put in a 290 to be safe. I have the same mods as you.

 

[stabor1122]

Thanks guys. Rep given where I could. Unfortunately it wouldnt let me give out to all but the info is very much appreciated. Gonna leave the 270 in for now till I can get to the Yamaha dealer later this week.