i got a 350X bored .60 over with a 12:1 piston, will i have to jet a factory 400ex carb. any input would be greatly appreciated, thanks

 

yes you'll have to jet, there's no way to be certain if the air flow of both machines is anywhere near the same, even though the bores are close. head design, pipe, intake, all add up to being different. the jetting will be close, but not necesarily right.

 

well i have a mikuni 38mm carb, it seems to me that its a little too big, i could jet it down, but would a 400ex carb be a better performer than that mikuni, what you think

 

I have a 38 mm Mikuni for my 350X and I can't seem to get it right. It idles good and has good top end but no midrange. Is your 38mm on your bike, and if so how is the midrange?

 

the midrange is unreal, the top end is okay, but it overloads if you dont stay in it, especially at idle, its a little rich, i wanted to jet it down, but didnt know what would be the best carb for the buck, do you know what jets you have in yours right now, or is it stock, im gonna put a cam and heavy duty springs in mine this summer, my valves start to rattle when the motor gets hot, so i will probally have to jet it bigger than what it is now, i think the main jet is 310, and the pilot is 35, its kinda hard to see, let me know what yours is, i really dont know if those are stock jets or not, it came off a big 2 stoke

 

That 38mm carb you have, is it a round slide or a flat slide? I've got a 36mm round slide on mine and I can't get the jetting right. It stumbles when I hit it hard and its really hard to start hot or cold.

 

its a round one, but mine starts real well, about one or two kicks, but the trick to starting mine is, you just cant get on it and kick, you have to kick it real slow about 3 times and pump the gas just a little, cause it will flood real easy, then you kick it hard and mine will fire right up, your jets might be too big, are you taking your lid off the airbox, cause they suck awhole lot of air, i have got 12 airbox vents on my breather box and lid, and still not enough, i dont think the jets in mine are stock, since i bought it used, but try that if you hadent already, let me know

 

My 350X has a Cobra exhaust and air box vents. My pilot is a 40 and my main is a 360. I think I need to change my needle and maybe the slide to help the midrange problem. Do you know what needle and slide you are running. I am running a roundslide mikuni. Thanks for the reply.

 

Has anyone ever had their head portedon their 350x? Trinity wants $350 for a full port job and rebuild of my head. They claim it will make a big difference. But is it worth it?

 

yea, you might need to jet it down a bit, and my needle clip is in the middle, mine has a white brothers e series muffler on it, it sounds pretty good, you might wanna jet your main to a 310 or 320,and you might wanna step down to a 35 on it, i have a book that tells exactly what to do if i can find it, i know your needle is mainly or idling, let me know what you tried