350x rev limiter?/ 400ex carb

[Tecate performance]

does anyone know for sure if the 350x has a rev limiter, i was under the impression it didn't, because they used to use the 350x cdi on the 250x's. but my recent project is either too rich or hitting it, its hard for me to tell somtimes because it rev's so quick. i'm running a 400ex carb, which works great, but at full throttle after a second or so it sputters like its up against a limiter. i'm at a 150 main. i tried a 140 but it was too lean, and 155 is too rich.

also, for anyone wanting to run the 400 carb, if you use the 300ex manifold it has a bigger opening that the 400 carb fits right into, no stretching. also, my 350x cable worked fine.

[350x'inNY]

1.) does anyone know for sure if the 350x has a rev limiter, i was under the impression it didn't, because they used to use the 350x cdi on the 250x's. but my recent project is either too rich or hitting it, its hard for me to tell somtimes because it rev's so quick. i'm running a 400ex carb, which works great, but at full throttle after a second or so it sputters like its up against a limiter. i'm at a 2.) 150 main. i tried a 140 but it was too lean, and 155 is too rich.

also, for anyone wanting to run the 400 carb, if you use the 300ex manifold it has a bigger opening that the 400 carb fits right into, no stretching. also, my 350x cable worked fine.

1.) The CDI doesn't have a rev limiter like you said.

2.) Those are some big jumps on the jet. 150 - 140... 150 - 155.... if it's the same jets that come on a 350X carb, you should be able to buy jets in increments of 2 or 2½.

Bruce

[smokinp]

do you have any pics of the 400ex mounted on the 350x?

[HRC1]

does anyone know for sure if the 350x has a rev limiter, i was under the impression it didn't, because they used to use the 350x cdi on the 250x's. but my recent project is either too rich or hitting it, its hard for me to tell somtimes because it rev's so quick. i'm running a 400ex carb, which works great, but at full throttle after a second or so it sputters like its up against a limiter. i'm at a 150 main. i tried a 140 but it was too lean, and 155 is too rich.

also, for anyone wanting to run the 400 carb, if you use the 300ex manifold it has a bigger opening that the 400 carb fits right into, no stretching. also, my 350x cable worked fine.
Does the 300 ex manifold bolt right to the 350x head? Or do you have to mod it some?

[Tecate performance]

the manifold bolts right on, just the carb opening is a little bit bigger. it makes mounting a 400ex carb or fcr easier. i'll get some pic's tonight.

i didn't think the 350x's had a rev limiter, so apparently its a jetting issue. as far as the jets go, yes they're the same as the 350x mains. so when i say i've gone from a 148 to a 155 its only been 3 sizes from the 148. with the 148, it was better but still missed at wideopen after two seconds, 150 was the same way. so all i have left is a 145 or a 142, thats not much of a range to play with. and the 140 seemed lean. i engagaged the choke with the 148 and it got worse, so i'm leaning toward too rich. it rev's real quick with the JE piston and lightened flywheel though.

[HRC1]

Any year 300 ex? any idea what size carb they used on them? The 400ex internal measures 38 mm i do believe, and the stocker for the 350 was a 34, If it's any year i got a few on ebay i can buy. Thanks for the tip!

[Tecate performance]

any year works, it looks just like the 350 boot, just has a bigger opening. the 300 used a 29 or 32 mm carb, (don't remember), its like the 350x's, but has an accelerator pump and a larger spigot on the front. you're better using the 400 carb though, its not too big or anything for the motor.

as far as jetting goes, i have an air leak around the helicoil insert for the sparkplug, so i think i found my high rpm misfire.

[HRC1]

i went to exriders.com last night and looked up what guys are using for adapting 400ex carbs to their 300ex's and 350x powered quads. They are using 30x boots dipped in boiling water and stretched. I know the 350x has a 34 mm carb stock and these guys are actually looking for 350x carb boots to use on their 300ex's for the swap. They said the boot itself is deeper on the atc and will hold better than the 300 boot. Have you tried the stock atc boot? I am just wondering, cause if the 300 boot is actually shorter that the atc boot, i'll just use what i got, can tell me the outer diameter of the stock 300 carb so i can compare it to my atc carb? i have digital calipers and i can post my outer diameter later tonight.

[Tecate performance]

i'm not sure we are talking about the same part. what i was talking about was using the 300ex manifold thats between the carb and the head. you still use the 350x airboot, which is between the carb and the airbox. the 350x manifold has a smaller opening for the carb than the 300ex. but the 350x airboot has more volume for flow, so thats why the quad riders use it.

as far as fitting the 400ex carb on the 350x, if you use the 300ex manifold, the only modification you'll have to make is to stretch the 350x airboot a bit to fit the flange on the carb. i heated mine up with a heat gun and then stretched it over the big end of a poland springs water bottle. its just about the right diameter and has a smooth transition so the boot doesn't tear. once it takes shape and cools, it fits good. then i used a 400ex clamp.

[HRC1]

Yah, we are talkin about the same part, And the 300ex guys are using 350x manifolds for the swap. Seems some 300ex riders have cammed and upped the compression and are using the 400ex carbs. And since their stock carb is only a 32 and the 350x is a 34 they are using the 350x manifold and stretching it to fit the 400 carb. They said the 350x boot is deeper and holds the bigger carb better. I am just repeating what i have read man, not trying to argue with ya. I was just wondering if you had compared the 2 manifolds and what the differences are. I am just having a hard time imagining a carb with a 32mm inner diameter having a larger outer than a carb with a 34 mm inner diam. If it works, i'll go that rout, but i held my stock 350x manifold up to the 400 carb and it aint goin in without heat and alot of coaxing. Like i said, i'm not flaming you or anything, just curiouse about the fit. If it works, i'm buyong one asap as i gotta get this thing on within a week, my new motor is together and i gotta tune it before i hit the dunes.

[Tecate performance]

the mainifold on the top is off a 300ex, the bottom one is off a 350x. i don't know if you can tell in the pic or not, but the 300 has a bigger opening, 40mm vs. 37mm. the size of the carb bore has nothing to do with the diameter of the spigot though. so i don't know what the people on exriders were saying, but its a whole lot easier to mount a 400ex carb in the 300 manifold vs. the 350x. good luck on your project, too.

[HRC1]

thanks for the pic! I'm hopping on ebay right now!

[NOS_350X]

Well if you have some muscle its not hard to get that 400ex carb over the 350x intake boot. I'm still messing with jetting, got it to rev out (wot) real nice but but duing fast accleration it dies and in the middle its sputtering.

[Tecate performance]

what main jet are you at and what other mods do you have to the motor?

[NOS_350X]

K&N, no airbox, slightly ported and exhaust. Nothing inside the engine yet. Main is a umm 170 moved and the thing that the jet screws into is screwed all the way in and needle is all the way in.

[Tecate performance]

is your needle all the way up(rich) or down(lean)? also, did you try the leaving the needle jet screwed in the stock position. i think if its up too far, it can starve for fuel under certain conditions. i measured mine and it was 11mm from the bottom to the jam nut.

[NOS_350X]

lean, and ive messed with every setting i can find, and still no solution to the cutting out.

[OldSchoolin86]

Cutting out like that or hesitating is usualy a sign of being lean. How rich have you tried going with the needle since the jet change?

[Tecate performance]

just a follow up on my problem, if anyone is still interested. i pulled the head and put in a time sert sprak plug insert, it now takes a B series ngk. no more air leak. well, the misfire was still there. played with the jets, from 135-180, ran better with around a 180, but still had misfire that came at about the same rpm each time. decided to try another cdi, and presto, no more misfire. the strange thing is that 2 years ago when it was parked, the bike ran great. no cdi issues to speak of.

as for the 400ex carb, it works great. i ended up with a 42 pilot, needle in 3rd position(stock 400ex), and a 175-180 mainjet depending on airbox lid being on or off. other mods: .080, 10:1, ported head, supertrapp 4", 10 discs, and no airbox lid(currently).