300ex cutting out...

[drifterx]

Hey, its kinds cold here, maybe bout 15 to 20. I been riding my 300, and it cuts out at about mid throttle every now and then. Its not too bad, still rideable. I let it warm up and everything too. I put a little bit of heat into the tank earlier, and i'm hoping that will help, but it hasn't helped yet. I haven't done any motor mods, except a little cutting on my muffler, and the spark arrester is off. Could my jetting be off though, just from that??? Could my valve clearance be off? Any imput is greatly appreciated. Thanks!!!

[300exOH]

Sounds like your jetting is the problem. They are lean from the factory and any mods will make it worse. It'll be even leaner when it's cold also. It wouldn't hurt to check your valves too.

[drifterx]

What do you suggest i go with for jetting? I think i'm going to get that powroll header thats designed to work with the stock muffler, and a K&N with no airbox lid, cause i want some more scoot, and can't afford sparks right now after i had a run in with a pole in my car (figures). I thought it might have been lean, cause i noticed that the exhaust gets really, really hot, and always has. It was hot enough that today when i was riding, i accidentially just barely brushed it with my thumb, and it was hot enough that it burnt, gave me a blister, and caliced the skin too. Thats pretty damn hot!

[300exOH]

I would start with a 42 pilot jet and go up maybe one size on the main. 122 is stock so I think it would be 125 or 128 keihin. Your air/fuel screw should be around 1 1/2 to 2 1/2 turns out. Also you may actually be losing power with a modded stock exhaust especially on the low end. Jetting for you will depend on your altitude so I can only make a guess. Also check your valves to be sure. ( .004" intake and exhaust )

Good luck

[drifterx]

Well, i haven't noticed any power loss after i modded my muffler. I only took off the plate under the tip, and then made the hole a tid bit bigger with a grinder. I was thinking about welding it back shut though, and just leaving the spark arrestor off, cause it sounds pretty good that way. I'm in northeast kansas, i have no clue what the elevation is, but it isn't too high. If i get the header and filter, what should i jet it for then? Thanks!

[300exOH]

Depends on what you buy. Whoever you buy the exhaust from should offer you jetting recommendations that will work. Any power loss will be minimal since you didn't change much. You basically just made it a little louder and more likely to cause a fire(no offense). Not sure about Kansas but I'm, only about 500' above sea level. I think you go up a main jet size about every 1000'. I can't really say exactly what jets you'll need since it varies greatly for everyone. I would start where I said above and see what the plug looks like it should be a tan color when it's right. I'm no jetting expert I honestly have very little experience. I just go by what I read.:o

[drifterx]

I was just trying to make it louder, it sounds like a royal wimp stock, you could hear the engine's moving parts, not the exhaust. Thanks for the help man! I appreciate it!