Jetting and needle setup

[Muller857]

hey guys, this is my first post i have had my banshee for about a week now and have been on here every night reading. Its a 97 stock rebuilt with wiseco motor at the end of last summer with new cylinders, crank, and head. Mods, Fmf gold series, proflow with no lid, stock carbs, boost bottle, tors eliminated and the seller didnt know much about it, but said the head was decked a little, he said 4 or somthing, so im guess .004. I think thats all. when i got it, or when i went at looked at it the guy didnt ride it since october so it was jetted for warmer air (chicago area) once i had it home i went and picked up some amsoil and 240 and 260 jets from a dealer, the service manager told me a 30 pilot and he said a 240 main, i thought from what i had read this would be lean, but i got that and then a 260 in case since fmf reccomended that. when i took the carbs off they had 220s in them, which i think is way wrong, but he said it ran good in the summer, and a 27.5 pilot. with the 240 it was fast but i was afraid it was lean, a 260 is ok, but seems to lose top end and i have a 290 in now which from what i have read seems to be where it should be, but it still loses top end. my needle says 5n7 on it which i think is stock, and it is set on the first notch from the blunt end(so leanest setting i think) i was messin with it and witht he needle in the middle pos. its hard to start and wont idle on its own, even if i mess with the idle and air screws. so i put it back where it was, here its about 600 feet and now around 30 degrees F, i mix 93 oct. with torqo race additive so it says it brings the octane to 104, and i mix to a 40:1 ratio with amsoil dominator. Sorry so long for a question that is gone over all the time, but this way you know everything that can help... THanks in advance guys.

[BansheeDan]

well first off get yourself a set of dyno jet needles...

they have a lil different taper to them then the stocks and also have 6 positions for adjustments.

 

second.....you see my mods in my sig,so u can use this just go a lil leaner then me for your elevation since im at 850-900 ft above sea level

 

i run stock pilot..310 mains in winter and 300 mains in summer

and i also run dyno jet needles in the 3rd clip position from the top

 

i would start with the 260's u have then do plug checks from there.....your plugs will tell you everything you need to know

 

 

 

Dan

Edited January 28, 2007 by BansheeDan

[IROOST1]

My mods are almost the same only difference is i have bills pipes and it didnt say what type of filter you have. I have a k&n. Im also at 775 ft elev at 30 degrees out. The needle position shouldnt affect the starting. I have had a pain in the ass time rejetting for cold but i would try 290 mains, middle clip, 30 pilots, .75-1 out on the air screw and stock(1.6) air jets. It sounds like you know how to get the carbs off so give that a whirl.

 

Also, dont get ripped off at the dealer, www.denniskirk.com sells the mains for 5 bucks a pair. Just get a bunch of em for when it warms back up.

[Muller857]

thanks dan and iroost, today was like negative 3 outside so i didnt do much with it, but as far as the clip position, i thought it wouldnt affect anything buy my mid power, but for whatever reason it wouldnt stay runnin without me on the throttle a little, so i thought maybe i forgot to do somthing when i had the carbs off to put the 290s in but when i switched the clip back to the top clip i didnt take the carbs off i just took the tops off, so i dont know what the deal is with that, it seems like i have read a lot of people like the stock needles so i would like to avoid getting new ones if i dont have to. ... Doesnt 220s seem lean as hell for summer, i know the guy who had it before me couldnt have ridden it hard because he had lost his right hand in an accident, so it would of been pretty hard to hang on with one hand when the powerband hit, so maybe that setup was workin for his purpose. i would think im gonn be at 260s in the summer at least, and 290s now when its below 30 out, but who knows, really i want to get that needle to work in the middle position. also i am goin to get some new reeds, sure they are gonna be v force 3s, so should i wait till i get them in to worry about this or will it not make much difference. thanks again, oh i have k&n filter

[IROOST1]

I think if you try out my jetting recommendation, it should get it close enough the reeds wont affect it. Also, if the head is decked, you should be runnin about 100 octane race gas. I dont believe in additives and what the companies say they do. Also, i would go 32:1 on the mix for the cold like most performance snowmobiles.

[Muller857]

Ya, i was skeptical of both the fuel additive and the leaner oil mix.. As for the fuel additive, i use 93 and torqo's octane leaded additive, it is according to the guys at the shop one of the only working additives, it was 16 bucks for a quart . it treats 5 gallons of 93 to 110 oct and 10 gallons to 104. i mixed for 104 but the previous owner said 93 was fine, but i would rather be safe than sorry for now. as far as the premix ratio, on the amsoil bottle it says to mix 50:1 for 250 and larger hp 2 stroke engines, and a few guys i know mix that and say its fine, but i went to 40:1 to be safe, obviously 32:1 is the safest. I think with not knowing the deal with the head and compression i might just invest in a cool head, and tonight i bought v force 3s off ebay for 201 shipped. Since its like 0 degrees here now and will be for a few days i will prolly wait to try tuning again once i get the reeds in, but i will definetly begin with your suggestions iroost, thanks. If i was to get a cool head, what dome size is stock compression, i would guess the higher the cc, the lower the compression. THANKS FOR READING,

[dajogejr]

22cc to 23cc is stock. I've read a machinist's post on here, and he said he's seen stock head range from 24.5 to 21.2 or something. 22 to 23 is supposed to be stock..roughly.

I'd say you're probably safe with 21cc domes and straight 93 octane pump gas.

 

I'm not a big fan of additives either...especially in a two stroke with premix in the tank...

[Muller857]

I talked to a torqo rep today for like 15 mins, he says the the additive is the same as the formula used for straight race fuel they supply only in a smaller, safer, quanity. he also said that tho is says when i mix it at different ratios for 104 or 110, it can acutally be +-2 octane. he also said that the orginal 93 oct from the gas station has different detergent ratings that effect the burning levels, he recommends, mobile first, bp second as they have the highest levels of octane witht he best burning detergents. I think if i did change the head and decide to run 19cc domes or a higher compression i would buy the straight race fuel, but for now i dont want to spend 60 bux for 5 gallons of 112. dammit its cold here, lata

[IROOST1]

Yeah, i always get the torco guys trying to sell me crap. If you live anywhere near a stock car track, you can get race gas anywhere from 100 to 110 for less than 5 bucks a gallon. Or a speed shop should have 5 gallon drums for about $45. Or find a snowmobile shop, they'll have the race gas this time of year. Personally i run a mix of 100 unl torco with 110 leaded pump fuel in my yz250. I have the stock head on my banshee so 93 is all it gets. Your best bet is to do an online search for gas stations that have race fuel. As for the cool head, its an excellent buy.

[Banchetta]

First thing I'd do is get a compression test on it...If your below 165psi, then I'd run straight 93 octane. Race fuel won't help out performance wise other than detonation. As long as your below 165psi you won't detonate. Next, I'd put some 300 mains in there for those temps...You'll probably be around a 260 in the summer, your needles should be 4th clip w. v-force reeds and 5th clip w/ stock reeds. 27.5 pilots for winter and stock 25's for summer. There is no way your top end is better w/ 240 mains.....your seat of the pants dyno isn't working too well...Run your shee wide open in 6th gear for 5-10 seconds, pull the clutch in, shut it down, coast to a stop, pull the plugs...light tan is lean, chocalate is perfect, black is rich...that'll get your mains dialed in...you might also want to get a new K&N filter...if the other owner used detergents to clean the filter, then it could very well be clogged and you can't clean it. Detergents will ruin a K&N and gums up the gauze in the filter..