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Not just another exhaust?
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Posted by: yellowWB400ex

I just got done "fabricating" a stock 400ex exhaust slip on onto a 250x with a cobra head pipe. The cobra broke and it is a P.O.S. so instead of buying a exhaust I was being recourceful and used what I had. It runs and doesnt backfire. It has descent bottom end but falls off on top (I think) but I have a 400 and the 250 is my friends and dont ride it much. So my questions are is this bad? Will it be ok? And what should the jetting be around, I have no idea where to start?

Posted by: yellowWB400ex

anyone?

Posted by: drifterx

I don't think it'd be a problem, i've seen quads and bikes with other quads and bikes exhausts.

Not sure about the jetting, you might just want to run it, and check the burn on the spark plug.

Posted by: riggsracing

if u take the baffle out it will prolly help, get better air flow

Posted by: yellowWB400ex

I did take the baffle out (spark arrester) it isnt very loud but it sounds descent.

Posted by: 300ex73

I got bored the other day, and since I'm getting a new exhaust soon anyways, I sliced about 3 inches off my Pro Circuit T-4. It works pretty good. Kinda loud though. Anyways, I noticed after I did my jetting was off. I had to up it from like a 128 to a 150. So if you're running a K&N or similar filter with no airbox lid, I'd recommend starting with about a 144 or 146 main jet. Also, seat the airscrew all the way, and turn it back out about 2-3/4 to 3 turns.

Posted by: yellowWB400ex

thanks alot but does the 250x carb use the same jets as the 400ex if so I would use my stock jet

Posted by: 300ex73

You definitely don't wanna use the stock jet. It'll run waaaay too lean. If you're running a 400EX carb, then get a jetting kit for a 400EX. Just put in between a 150 or 155 main jet either way, and it should work great.