Fst 390ex

[Built_300EX]

Ok, I am sending my motor off shortly priced at $1941.00. I am getting the following:

390cc big bore, stroker crank, heavy duty rod, oil cooler, +1mm valves (intake and exhaust), port/polish, 336. lift cam, hardened rocker arms, valve springs, clutch springs, and all of the motor fully assembled and put together ready to bolt on. What will I be running with does anyone have this done to theres? Also, what kind of carb should I put on this, no matter the price just let me know. I have a brand new Yoshimura full exhaust system, K&N air filter with pre-charger, 14/36 gearing (renthal), RK 520 X-ring chain, modified airbox lid and some other small stuff to take weight down from the heavy stock objects. The way the guy at fourstroke tech talked, this b*t*h will rock. =) I am thinking about putting an Edelbrock carb on it any other things I should do? Also I heard something about 3rd and 4th gear mods that should be done with big bores? Hell if I know, just update me soon. I need to know before I get this sent off so I can get it priced with those mods etc.. Thanks.

[bradley300]

FST can tell you all about the 4th gear mods, i would use a stock 400ex carb

[06yfm350]

edelbrock quicksilver carb.. people swear by them.

[dork]

you'll have an animal if its done right, which it sounds like it will be. i put a FST 380 kit in my buddies '01, but it was a bore only, and i think thats what he sells for the 300ex, no stroker. you may want to get the 380 kit since it gives you one .040" overbore (which will make it a 390) and the power difference will be negligible. FST uses a stronger rod with that kit and bigger wrist pin which are the weak spots on that motor. also what cam are you using, the one he sent me was .360 lift, you'll probably want to go bigger than what you have listed if its an off the shelf .335 web or megacycle.

the 300ex trans. is pretty strong, even with more cc's. you shouldn't need any mods. the 250x's had problems with 3rd, and i think you could put in the 300ex 3rd&4th which were improved. just make sure you're clutch is in good shape and use his clutch springs(they're green). this one's going on 3 years now with no problems, you've got to use good oil (like rotella 15w40)and change it often though.

for the carb i started with a 400ex carb which works good for the money. then we switched to a fcr39 which works great and really brings it to life. the edelbrock carb is good too, but be sure to get one for a 400ex or 440ex. make sure your exhaust has an oversize head pipe. i run 15/36 gearing with 20" tires and no rev limiter. i estimate top speed to be 68-70mph.

[TarheelRedRider]

Originally posted by 06yfm350
edelbrock quicksilver carb.. people swear by them.

Yeah I love mine, worth every penny.

[humblesquirel21]

i love my edlebrock to holds up to all of their claims

[Meghan Thompson]

Originally posted by dork
i run 15/36 gearing
By the way this is Built_300EX but I am at my girlfriends and I am too lazy to switch over users. Please PM where you can buy the 15. I can only find a 14/36 gearing I had a 15 on the last 300EX I had but it was by Titax and they no longer make them. Update me soon. Thanks.

[dork]

i got mine from here (http://www.cycleworksracing.net/300ex.htm), its a PBI. sidewinder makes them too.

[TarheelRedRider]

Originally posted by humblesquirel21
i love my edlebrock to holds up to all of their claims

I like how easy it is to tune.

[zeppelin]

Originally posted by 06yfm350
edelbrock quicksilver carb.. people swear by them. alot of people swear at them too.... id see if i could find a carb off of a 250f, they are usualy about 39mm so its about the right size. if you want a smaller one id look for a carb from a drz350.

[dork]

the carbs off the yz250f and kx/rm250f are 37mm. the new cr250f is 40mm. if you use a FCR for a 400ex the flange adapters are the right length and diameter so it will fit easier than the dirt bike carbs. if you want something smaller than 39 in a FCR, sudco sells a 35mm kit for the xr250 dirtbike that will mount up.

[humblesquirel21]

[QUOTE]-------------------------------------------------------------------------quote:
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Originally posted by humblesquirel21
i love my edlebrock to holds up to all of their claims
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I like how easy it is to tune


i lvoe the anti slosh plate i almost totaled my quadn when i had the stock carb on because i went up a huge face (liek they do at the dunes) and i was pullin a 180 on it and it quit on my right at the top belive it or not i bailed quick enough that the quad jsut sat there almost ready to tip but no quite long story short after fear full mins i got it down now with my edle i can do "wall"rides liek that and not die which is why i bought it

[2muchquad]

Ok, I am sending my motor off shortly priced at $1941.00. I am getting the following:

i have not even $300 into my 385 kit.but i also did all my own work except for the sleeve installation.results? probably one of the fastest under 400cc 300ex based machines in the ohio-pa area.am i sure about that? i put my money where my mouth is.:)

[Built_300EX]

picturetrail.com/Project390EX