300EX carb question

[Scott]

OK guys, I've just put on a 4" supertrapp and I want to make sure I'm jetted properly. Tomorrow I'll do a couple test runs and check the plug, but I have a couple questions that would be helpful before.

First, what is the stock main in the 300 carb?
Second, I was thinking the only jet I would have to change is the main. Right or wrong?
While I'm at it, mine is very cold natured, so bumping the pilot up a notch should help the starting/idle, right? What size is the factory pilot?

The engine internals are stock, but I added a K&N filter/outerwear and a DG headpipe w/ a 4"supertrapp. I can't remember exactly how many discs, but it's about 10 minimum and there was no packing in it when I pulled the baffle out. It's a supertrapp endcap, but I'm thinking of getting a TC style open cap. I don't think the exhaust can get much more free-flowing.

Thanks in advance.

[Scott]

I've seen a couple different versions of what is "stock" for a 300 carb on here. One post says that stock is:
main 140
pilot 42

but then another post says the 300 is
main 122
pilot 40

There's a difference between the stock jet size for a 400 and the stock jets of a 300, right?

So is the 300 a 122 stock and the 400 is the 140? I would like to pick up the jets today on my way home so I'll have them to tinker with tomorrow.

I just re-jetted my 300ex last weekend. It had a 122 in the main. I did not change the pilot, so I do not now what size it is.

I have the wb e-series pipe and K&N filter and I used a 130 main jet.

[Scott]

The stock jet is a 122. I swapped it for a 125 and it seems fine, no cutting out, no blubbering. I'll know more when I get a chance to do a couple WOT plug checks. Since there wasn't much response to this, I'll post whatever answers I find. Another 300 set the same way as mine also ran a 125. He could run a 128 in the summer, but it would cut out when the temp dropped. A 130 was too rich for his, but robertmac03, you don't have any trouble with the 130 in yours?

And I can't explain why my friends worked with a 125 and not a 128. As the temp drops, the air is denser and it should be leaning out your carb, so I have no idea why going to a leaner jet worked for him.

I found that the 130 jet made it sluggish when I first fired it up. But after a few minutes of riding it stopped. I checked the plug and noticed that it did look a little rich. I have since added the wb header pipe and 4 1" holes in the air box lid. It seems to be right on now.

:)

[Scott]

The WB and lid might be the difference. I'm still running the stock airbox lid w/ no holes.

[2K1 300EX]

On a 300ex the stock jets are as follows:the main jet is a 122 and the pilot is a 38. Hope this helps.