Ok, I moved the clip on my buddies 400ex with the red glowing pipe. I took them down two clips, and that put them one from the bottom with a 165 jet. So we fired it up, and instead of turning red quickly, it took a long time at 1/2 throttle sitting still to turn them red. But they did eventually turn red. What should I do now? Move the clip again, or go back to a 160 jet?


As for the 300ex, I pulled the carb apart and there is nothing underneath the floats. They just hang there, with nothing to support them. What should I do since it cuts out when you are on a hill, and gas come out the overflow when you are wheeling it?

 

As for the 400ex, its not that uncommon for the headers to turn red while sitting still. My DS's fan would NEVER turn on unless i let it idle for a while. Ride it around and see what the headers look like.

I cant help you with the 300, im sure someone can.

 

Alright thanks.

 

yeah, the headers may turn red a little bit. with the warmer months coming, i wouldn't richen it up anymore. yeah, a 165 is too big in my opinion unless you have some decent motor mods done.

 

It's my ex. The mod's are listed below in my signiture. I have run every application that I can. I have run 160 with the clip at every position. The 160 with the needle clip set at 1 up from the bottom took about 1minute 30 seconds before the headers turned red. But it was a rich setting. The 165 jet, with the needle clip on 2 took 2 minutes to turn red, and was alittle rich.

So do you have any other suggestions?

 

Do not attempt to tune by if the pipe is glowing or not. Red glowing stainless steel pipes are pretty normal.

Tune by how the quad runs and by plug color.

300EX - floats are supposed to "just hang there". They float in the gasoline in the carburetor bowl, that's their job. Gas coming out the overflow when in a wheelie is also normal, that's why it's there, to allow fuel to escape when the floats can't properly regulate the flow due to an abnormal condition like a wheelie or on a steep hill climb.

If the 300EX is cutting out on hills you might make sure the overflow tube is clear and can flow freely because if it can't, it will cause an overly rich condition that will make the engine cut out. If the quad is old you might also check to see if the needle/seat assembly is cutting off the fuel properly when the floats rise. Also check to make sure no fuel is trapped in the floats.

At this point, it really sounds like you need to study up on carburetor theory so you understand how they work. You can easily screw things up if you don't have a clear understanding of what you're doing.

 

The problem on the 300ex is that the floats do not snag or catch at a certain point. The carb's on my Raptor, or on my buddies 400 will catch. The older model 300ex is very loose. If you tinker with the pin on the floats, you can get them to catch and and not bob around. It seems the pin on the floats is woren out.

We were trying to figure out what to do on the EX, because the pipes didn't start glowing red until after we put on all the mod's. We have run several differnt runs to get the jetting right, and try to keep the pipes from turning red. I have plenty of experience with carb's, and the jetting for rich/lean is no problem. Just the pipes glowing red after a prolonged 1/2 throttle run without letting off the gas. As soon as they turn red you can let off the gas and it will turn back to normal color.

 

on the 400ex, you will get a little glowing of the pipes. is it glowing at idle, 1/8 to 3/4 throttle, or full throttle??

 

The 400 only glow's at prolonged 1/2 and over throttle runs. It only turns red when parked, and over 1/2 throttle for over a minute straight. And they sometimes glow red when your riding it at 3/4 throttle and more for a long period of time.

 

the stainless steel pipes do have a tendency to glow a bit. i would be running a 40 or 42 pilot jet with a pipe/filter. this should make the bike easier to start and should prevent the glowing at idle. if you don't want to buy a new pilot jet, just try to turn the fuel skew on the bottom of the carb out 1/2 a turn or so.