jetting???

[BigDave]

Does this look like it needs jetting. It has a larger headpipe, silcencer. And will have a k&n soon.
http://host5.dominet.net/~hatch195/images/untitled1.jpg

It does make a popping sound as I throttle down. While im still in gear, just let off the gas, it sounds like a backfire. But if i hold the clutch, hit the rev limiter, let off the gas, no backfire. So im not sure if maybe its popping because of the spark arrestor removbed and NO disc in the supertrap :ermm:

[JOEX]

From what I understand doing a plug check with todays fuels is questionable unless done correctly due to the additives in the fuel.
Also usiong picture on the internet probably isn't the best way to compare colors due to various monitor/computer settings.
Look around this section of the forum and you will probably find your answer or something close.

Here is a copy of part of a thread that I saved sawhile ago that might help with doing a plug check.......



Mickey Dunlap...
With all the different kinds of fuel we see (including unleaded) there is no way to get the right color.The way I read a plug is to ride for 10-15 min. to get it up to temp.Run down the road wide open in the top gear and hold it there for 5-10 sec. then kill the motor, pulling in the clucth and come to a stop. Pull the plug and look at the ground strap,you want to see a carbon line in the middle of the 90*bend. If the line is closer to the tip of the strap its to rich. If it is down around the 90* bend towards the plug threads its to lean.This works on 2 and 4 strokes.It does not matter what color the plug is just make sure you use a used plug that has carbon on it.




-------------------------------------------------
Reading Mr. plug can be Voodoo at best with today's lean fuel. Try this test, I have used it when reading plugs made me crazy.


The Roll-Off technique is the quickest and is almost as accurate as the Roll-On method. First, one gets the engine warm on the way to a safe roadway. If there is room, use fourth gear as this allows more time to assess the result.

Now, get the engine rpm high enough that it is on the cam and in its power band. This may need to be as high as 4000 rpm with some cam choices. Apply full throttle. Let the engine accelerate for a couple of seconds until it has settled in and is pulling hard. Quickly roll the throttle off to about the 7/8ths position. When you do this, the mixture richens slightly for a second or so.
If the engine gains power as you roll the throttle off, then the main jet is too small and you need to fit a larger one.
If the engine staggers slightly or has a hard hesitation, then the main jet is too large and you need to fit a smaller one.


__________________
White_Knuckles


Joe

[cals400ex]

i have never heard of checking your these two ways, however they make sense. is your jetting stock right now? to me, it looks as if your jetting isn't stock by the way your plug looks if you have a pipe on right now. i do know the fuel additives change the color of the plugs. with shell fuel, my plug turns a light yellow color.

[BigDave]

Originally posted by cals400ex
i have never heard of checking your these two ways, however they make sense. is your jetting stock right now? to me, it looks as if your jetting isn't stock by the way your plug looks if you have a pipe on right now. i do know the fuel additives change the color of the plugs. with shell fuel, my plug turns a light yellow color.

I do have stock jetting. Somone said perhapse it may not need jetting from the non bronze look on the plug :ermm:

[cals400ex]

i would get a new plug and go from there. when you took this pic, was the plug cold or did you just get done riding? was the bike idleing for a while before you took this pic? what kind of pipe you have? i would think you would want to go up on the mainjet one or two sizes if you have a pipe and are getting a K&N soon.

[BigDave]

bout 15 minutes worth of riding. I just killed the bike and took the picture. I will try 3 jets larger. My kit should be in today, so ill be able to see what it is :huh

[BigDave]

the popping noise is from not having any disc in the muffler. I just got my jetkit and k&n. With just the k&n...it rides like a TURD. So it must need jetting. It kind of surges since I put the k&n on. Dynajet recomended a 128 jet with an open k&n and a larger exhaust. Does a 128 sound right?

[cals400ex]

i am not sure what a stock mainjet is on a 300ex. also, a 128 dynojet is about a 130 keihin jet. the sizing is different from keihin to dynojet.