mopar1rules

....X2. i would also leave the needles alone (clip in middle position) and stock pilots in for now. just play with the airscrews and if it is still lean after turning the airscrew in, so its only 1/2 turn out from closed, than bump up 1 size on the pilots and go back to 1-1/2 turns out with air screws and fine tune from there.

i would deffinetly go back to the br8es plug, as it is a little hotter than the br9es plug that you use now. that will help the plug from fouling and loading up. also, clean your pilot jets. they might be getting dirty. what's weird is that you said that it starts on the 1st kick, so i would assume that your pilot jets are clean. check 'em anyways. you can even try turning the air screw in. if the bog starts to go away, than you know it was a lean issue. if the bog gets worse, than you know its rich. what are the temps/elevation that you are running the atv in.

sorry to hear of your disaster man. i never had trouble though with the pro-x pistons that i have ran and am currently running though. dunno?

well for your mains, i would start at 260. leave the needles alone and pilots alone for now. you might have to play with the air screws a little. for bolt on mods, it would depend on where you ride. meaning sand dunes or what not. do you just trail ride? i need to know your riding style b4 i can tell you what mods to do. some that you can do wether you trail ride or not are the +4 timing, and carbon tech reed petals. if you want this thing to have more flow/power at mid to top, then get the v-force's. if you ride in the sand, i would probably stick to a foam filter, as it will provide better filtration of the sand, so your motor doesn't suck it in. you can get pods if you stay out of water puddles. you can run stock airbox with lid off, or drilled to look like swiss cheese, with a k&n filter. i can't tell a specific dome size yet on the noss head, cause i don't know what you plan on doing with the atv, but for average trail riding, 22cc domes will suit you fine. if you want higher compression and don't mind mixing race gas with 92 pump gas, you can run 19cc domes. if you want to run on straight race gas, you can run 17cc domes. i don't see the need for a different cdi box. if it were me, i would spend the $ elsewhere. don't get a boost bottle....they only crack your intake boots and suck $35 out of your wallet. that $35 could buy you the adjustable timing plate from ricky stator, to advance your timing +4. and it will actually do something.

you can send it to jeff @ midwest crank in green bay, wisconsin. he does the warranty work for yamaha, covering 28 states. let me know if you want the address

the temps that you will be riding in will play a roll as well in the jetting department. i would start with 350 mains, stock needles w/clip in middle pos, 27.5 pilots, and air screws at 2 turns. depending on the temps, you might be able to drop back down to 330 mains. start fat with the 350's though. you will likely need to stick to the 27.5 pilots.

coils can go weak. most people think they either work or don't work. well my buddies shee had a weak coil. shee would kinda stutter and not pull proper rpms at top end. put new coil on it and it worked great. oh yeah, my gap is set at .015" w/no problems.

i was told that namura pistons are junk. i would stick to wisecos or pro-x. i personally have pro-x pistons and have had no trouble or complaints. with shaving .02" off the head, i don't see why you would have to recut the squish angle, cause i believe the squish clearance is still plenty safe.

exactly....the three bond 1194 is what to use. if you find some 1104 at some shop, that will work too. its just an older version of the 1194. 1194 now replaced the 1104. the formula was changed a little.

well, if there is any cylinder scoring, then you will need to go will whatever size piston that you bored the cylinders out to. if you are keeping the piston the same size, cause the cylinders are fine, then you can get some wiseco or pro-x pistons from parts unlimited or some of the sponsors on this site that are .02 oversized as well.

how did you like the fattys? how did they rate to you, when compared to the others you tested?

i would start out at stock needle w/clip in middle pos, 27.5 pilots, 2 turns on air screws and 310 mains. could possibly go back to stock pilots. you might need to go to 320 mains, but i doubt it.

no. there's no need to be going any richer than 240 for mains. chevytrucks, how many turns are you currently out on those airscrews? just try 27.5 pilots and like 1-1/2 to 2 turns out on airscrews. see what ya get there. asrbanshee, you don't want to mess with the main jet, to cure a cold starting problem. gotta play with the airscrews and pilot jets.....things that have the greatest affect on the low end:)

.....second that

chevytrucks, turning the air screws in will richen the low end, cause it reduces the amount of air that gets mixed in with the pilot circuit. find out what pilots you have and let me know.

deckheight, do you know what the stock cc size is on a stock unmilled head? also, whats like the tightest that one would want to run his squish....like .040? for pump gas i mean.

at the small motors shop that i work at, i tore the top end off a ktm 50 that was in need of a rebuild. it has seen nothing its whole life, but klotz oil and i've never seen such carbon, and funky buildup in my life...ever. the dome of the head, piston crown, and rod, were just all covered in a hard dry carbon. in the bottom of the crankcase, was a weird black/grey oily mixture. a buddy of mine also started using klotz oil in his snowmobile and its also creating a greyish/black residue in the crankcase. from what i've seen klotz is junk. don't get me wrong, its smells good. my shee that i tore down for porting, had no blow by what so ever on either piston, and its seen nothing but amsoil dominator its whole life. engine was nice and clean, w/a nice amount of oil coating on all the engine parts. dome of head and piston crown had a slight oily residue that could easily be wiped off and it was not hard carbon. i'll continue to run amsoil and stay away from klotz. i'll use what i've seen to be good and stay away from what i've seen to be bad.

p-man, i can mill your stock head if you want. i've done mine before and some other heads for sleds and such. let me know if you want it milled. then let me know how much you want taken off, if you want me to mill the head.

jet kits are JUNK PERIOD! don't spend the $. just jet accordingly and you will be fine.

there is no theory. and that's not that lean on the oil mixture. there are trail bikes by me that run 80:1. the reason yamaha says to run 20:1 or whatever, is cause the oil was such shit back then ('87 when they came out w/the shee), but the oil quality has greatly gone up since then and they just left those premix recommendations the same. if you are running a good quality synthetic oil like amsoil dominator, then you will still be getting enough lubrication at a 50:1 ratio. 40:1 would be more rich than you would ever be wanting to go. you will also be spending less on oil, cause the quart will last you longer, seeing as you don't have to mix it as rich:)

start out at a 300-280 main, stock needles, stock clip position, stock 25 pilots, 1-1/2 turns on the pilot screws. you may need to go up to 27.5 pilots, but mine is fine at stock pilots, so i would start there.

it it were me, i would be running an oil content no richer than 40:1. i personally run 50:1 and am still getting more than enough lubrication.

hell, maybe even try a 330 off the bat, as long as a store is nearby and they are only $2.50 each.

yes, you'll need like i said a 300-320 main, with your pipes and lid off the airbox. start with 320's though.

so you have the old pipes that only say "gold series" or do you have fattys or sst's....what? you probably have to jump up like 2-3 sizes on your mains.