Please Help! I'm losing patience!

[MichiganRedneck]

ok, i get my trike out to ride it. YTM 200k. it starts right up, and idles perfect. i ride it around and it runs good. i get on my trail that is pretty straight so i can open it up a little bit. i hammer the throttle, and the motor starts missing. i mean missing bad. but if i let off the throttle and just drive it around without hammering it, it runs fine. over winter, i had it bored .50 over. so i thought maybe the jetting was lean. i bring it up to my garage, pull the plug, and sure enough, its white. so i took the main jet out, and brought it to my local yamaha dealer. i told them i need a bigger main jet, so for 5 bucks, i went from a 58 mikuni and bought a 60. i put it in when i got home and it still runs like crap. the carb is rebuilt and clean. is it timing? is it fuel? please help!

[nouseforaname90]

Sounds to me like something in the carb. I'd place my bet on it not being tuned properly.

[Rex Karz]

A loose wire could cause "missing".

[MichiganRedneck]

i was leaning towards carb problems. could a float not adjusted properly cause this?

[Dave223]

by chance, have you checked to see if the exhaust is clogged? sounds funny but if its clogged somewhat, it will idle fine, but miss and seem to lose power at higher rpms. Just a thought, Dave

[3leggeddog]

i say continue to play with the jetting.try to go up another jet size.buy a 62 65 and a 68.

[Erics350x]

try turning your mixture screw in alittle. my wifes ytm225 has to be ajusted about every week.

[MichiganRedneck]

my fuel/air screw does absolutely nothing. i can turn it in and it will run the same way as if i turn it all the way out. it has no effect on my trike running properly. im gonna give it another try today. maybe ill have some luck. give me some more suggestions. could it be a timing issue?

[Vealmonkey]

If your turning the air fuel mixture screw and it is doing nothing, I'd say your carb is dirty and something is clogged. Your air fuel mixture screw should have an effect. Unless it is just the fact that your jetting is still so far off. I'd say the problem is with the carb not anything else. Wether it is jetting or dirty carb I'm not sure. Did you take your time and break you engine in? If not be careful.

[MichiganRedneck]

i did break the motor in. but i found the problem, i purchased the wrong pilot jet for the carb. (wrong yamaha part #) i put my stock one back in and now it runs like a raped ape. thanks for the help!